idnits 2.17.00 (12 Aug 2021) /tmp/idnits42095/draft-ietf-extra-imap4rev2-24.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack an Introduction section. ** There are 3 instances of too long lines in the document, the longest one being 2 characters in excess of 72. -- The draft header indicates that this document obsoletes RFC3501, but the abstract doesn't seem to mention this, which it should. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document seems to contain a disclaimer for pre-RFC5378 work, but was first submitted on or after 10 November 2008. The disclaimer is usually necessary only for documents that revise or obsolete older RFCs, and that take significant amounts of text from those RFCs. If you can contact all authors of the source material and they are willing to grant the BCP78 rights to the IETF Trust, you can and should remove the disclaimer. Otherwise, the disclaimer is needed and you can ignore this comment. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (January 5, 2021) is 500 days in the past. 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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'IMAP2' is mentioned on line 7091, but not defined == Missing Reference: 'IMAP-OBSOLETE' is mentioned on line 7086, but not defined == Missing Reference: 'IMAP-COMPAT' is mentioned on line 7076, but not defined == Missing Reference: 'IMAP-HISTORICAL' is mentioned on line 7081, but not defined == Missing Reference: 'RFC-822' is mentioned on line 7095, but not defined ** Obsolete undefined reference: RFC 822 (Obsoleted by RFC 2822) == Missing Reference: 'IMAP-MODEL' is mentioned on line 7025, but not defined == Missing Reference: 'IMAP-DISC' is mentioned on line 7014, but not defined == Missing Reference: 'RFC3503' is mentioned on line 6987, but not defined == Missing Reference: 'IMAP-KEYWORDS-REG' is mentioned on line 7054, but not defined == Missing Reference: 'SMTP' is mentioned on line 7035, but not defined == Missing Reference: 'RFC7888' is mentioned on line 7010, but not defined -- Looks like a reference, but probably isn't: '1' on line 895 == Missing Reference: 'IMAP-URL' is mentioned on line 7049, but not defined == Missing Reference: 'TLS' is mentioned on line 1206, but not defined == Missing Reference: 'UIDVALIDITY 3857529045' is mentioned on line 5785, but not defined == Missing Reference: 'UIDNEXT 4392' is mentioned on line 1747, but not defined == Missing Reference: 'RFC2193' is mentioned on line 6997, but not defined == Missing Reference: 'RFC3348' is mentioned on line 7371, but not defined ** Obsolete undefined reference: RFC 3348 (Obsoleted by RFC 5258) == Missing Reference: 'RFC4314' is mentioned on line 7042, but not defined == Missing Reference: 'RFC3501' is mentioned on line 7072, but not defined ** Obsolete undefined reference: RFC 3501 (Obsoleted by RFC 9051) == Missing Reference: 'UIDNEXT 2' is mentioned on line 3281, but not defined == Missing Reference: 'UIDVALIDITY 1' is mentioned on line 3353, but not defined == Missing Reference: 'CHARSET-REG' is mentioned on line 7064, but not defined == Missing Reference: 'IMAP-I18N' is mentioned on line 7019, but not defined == Missing Reference: 'HEADER' is mentioned on line 5803, but not defined == Missing Reference: 'BADCHARSET UTF-8' is mentioned on line 3933, but not defined == Missing Reference: 'UID' is mentioned on line 4361, but not defined == Missing Reference: 'RFC2087' is mentioned on line 7046, but not defined ** Obsolete undefined reference: RFC 2087 (Obsoleted by RFC 9208) == Missing Reference: 'IMAP-MAILBOX-NAME-ATTRS-REG' is mentioned on line 7059, but not defined == Missing Reference: 'READ-WRITE' is mentioned on line 5787, but not defined == Missing Reference: 'RFC4422' is mentioned on line 6134, but not defined == Missing Reference: 'IMAP4' is mentioned on line 6219, but not defined == Missing Reference: 'Namespace-Response-Extensions' is mentioned on line 6289, but not defined == Missing Reference: 'IMAP-TLS' is mentioned on line 7099, but not defined == Missing Reference: 'RFCXXXX' is mentioned on line 6827, but not defined == Missing Reference: 'RFC5465' is mentioned on line 7006, but not defined == Missing Reference: 'RFC5256' is mentioned on line 6992, but not defined == Missing Reference: 'IMAP-UTF-8' is mentioned on line 7117, but not defined == Missing Reference: 'RFC3516' is mentioned on line 7213, but not defined ** Downref: Normative reference to an Informational RFC: RFC 2152 (ref. 'UTF-7') ** Downref: Normative reference to an Informational RFC: RFC 2683 (ref. 'IMAP-IMPLEMENTATION') ** Downref: Normative reference to an Informational RFC: RFC 2180 (ref. 'IMAP-MULTIACCESS') Summary: 9 errors (**), 0 flaws (~~), 40 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Melnikov, Ed. 3 Internet-Draft Isode Ltd 4 Obsoletes: 3501 (if approved) B. Leiba, Ed. 5 Intended status: Standards Track Futurewei Technologies 6 Expires: July 9, 2021 January 5, 2021 8 Internet Message Access Protocol (IMAP) - Version 4rev2 9 draft-ietf-extra-imap4rev2-24 11 Abstract 13 The Internet Message Access Protocol, Version 4rev2 (IMAP4rev2) 14 allows a client to access and manipulate electronic mail messages on 15 a server. IMAP4rev2 permits manipulation of mailboxes (remote 16 message folders) in a way that is functionally equivalent to local 17 folders. IMAP4rev2 also provides the capability for an offline 18 client to resynchronize with the server. 20 IMAP4rev2 includes operations for creating, deleting, and renaming 21 mailboxes, checking for new messages, permanently removing messages, 22 setting and clearing flags, RFC 5322, RFC 2045 and RFC 2231 parsing, 23 searching, and selective fetching of message attributes, texts, and 24 portions thereof. Messages in IMAP4rev2 are accessed by the use of 25 numbers. These numbers are either message sequence numbers or unique 26 identifiers. 28 IMAP4rev2 does not specify a means of posting mail; this function is 29 handled by a mail submission protocol such as the one specified in 30 RFC 6409. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at https://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on July 9, 2021. 49 Copyright Notice 51 Copyright (c) 2021 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (https://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 This document may contain material from IETF Documents or IETF 65 Contributions published or made publicly available before November 66 10, 2008. The person(s) controlling the copyright in some of this 67 material may not have granted the IETF Trust the right to allow 68 modifications of such material outside the IETF Standards Process. 69 Without obtaining an adequate license from the person(s) controlling 70 the copyright in such materials, this document may not be modified 71 outside the IETF Standards Process, and derivative works of it may 72 not be created outside the IETF Standards Process, except to format 73 it for publication as an RFC or to translate it into languages other 74 than English. 76 Table of Contents 78 1. How to Read This Document . . . . . . . . . . . . . . . . . . 5 79 1.1. Organization of This Document . . . . . . . . . . . . . . 5 80 1.2. Conventions Used in This Document . . . . . . . . . . . . 5 81 1.3. Special Notes to Implementors . . . . . . . . . . . . . . 6 82 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 83 2.1. Link Level . . . . . . . . . . . . . . . . . . . . . . . 7 84 2.2. Commands and Responses . . . . . . . . . . . . . . . . . 7 85 2.2.1. Client Protocol Sender and Server Protocol Receiver . 7 86 2.2.2. Server Protocol Sender and Client Protocol Receiver . 8 87 2.3. Message Attributes . . . . . . . . . . . . . . . . . . . 9 88 2.3.1. Message Numbers . . . . . . . . . . . . . . . . . . . 9 89 2.3.2. Flags Message Attribute . . . . . . . . . . . . . . . 11 90 2.3.3. Internal Date Message Attribute . . . . . . . . . . . 13 91 2.3.4. [RFC-5322] Size Message Attribute . . . . . . . . . . 14 92 2.3.5. Envelope Structure Message Attribute . . . . . . . . 14 93 2.3.6. Body Structure Message Attribute . . . . . . . . . . 14 94 2.4. Message Texts . . . . . . . . . . . . . . . . . . . . . . 14 95 3. State and Flow Diagram . . . . . . . . . . . . . . . . . . . 14 96 3.1. Not Authenticated State . . . . . . . . . . . . . . . . . 14 97 3.2. Authenticated State . . . . . . . . . . . . . . . . . . . 15 98 3.3. Selected State . . . . . . . . . . . . . . . . . . . . . 15 99 3.4. Logout State . . . . . . . . . . . . . . . . . . . . . . 15 100 4. Data Formats . . . . . . . . . . . . . . . . . . . . . . . . 17 101 4.1. Atom . . . . . . . . . . . . . . . . . . . . . . . . . . 17 102 4.1.1. Sequence set and UID set . . . . . . . . . . . . . . 17 103 4.2. Number . . . . . . . . . . . . . . . . . . . . . . . . . 17 104 4.3. String . . . . . . . . . . . . . . . . . . . . . . . . . 17 105 4.3.1. 8-bit and Binary Strings . . . . . . . . . . . . . . 18 106 4.4. Parenthesized List . . . . . . . . . . . . . . . . . . . 19 107 4.5. NIL . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 108 5. Operational Considerations . . . . . . . . . . . . . . . . . 20 109 5.1. Mailbox Naming . . . . . . . . . . . . . . . . . . . . . 20 110 5.1.1. Mailbox Hierarchy Naming . . . . . . . . . . . . . . 21 111 5.1.2. Namespaces . . . . . . . . . . . . . . . . . . . . . 21 112 5.2. Mailbox Size and Message Status Updates . . . . . . . . . 23 113 5.3. Response when no Command in Progress . . . . . . . . . . 23 114 5.4. Autologout Timer . . . . . . . . . . . . . . . . . . . . 23 115 5.5. Multiple Commands in Progress (Command Pipelining) . . . 24 116 6. Client Commands . . . . . . . . . . . . . . . . . . . . . . . 25 117 6.1. Client Commands - Any State . . . . . . . . . . . . . . . 26 118 6.1.1. CAPABILITY Command . . . . . . . . . . . . . . . . . 26 119 6.1.2. NOOP Command . . . . . . . . . . . . . . . . . . . . 27 120 6.1.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . 27 121 6.2. Client Commands - Not Authenticated State . . . . . . . . 28 122 6.2.1. STARTTLS Command . . . . . . . . . . . . . . . . . . 28 123 6.2.2. AUTHENTICATE Command . . . . . . . . . . . . . . . . 29 124 6.2.3. LOGIN Command . . . . . . . . . . . . . . . . . . . . 32 125 6.3. Client Commands - Authenticated State . . . . . . . . . . 33 126 6.3.1. ENABLE Command . . . . . . . . . . . . . . . . . . . 33 127 6.3.2. SELECT Command . . . . . . . . . . . . . . . . . . . 35 128 6.3.3. EXAMINE Command . . . . . . . . . . . . . . . . . . . 37 129 6.3.4. CREATE Command . . . . . . . . . . . . . . . . . . . 38 130 6.3.5. DELETE Command . . . . . . . . . . . . . . . . . . . 40 131 6.3.6. RENAME Command . . . . . . . . . . . . . . . . . . . 41 132 6.3.7. SUBSCRIBE Command . . . . . . . . . . . . . . . . . . 44 133 6.3.8. UNSUBSCRIBE Command . . . . . . . . . . . . . . . . . 44 134 6.3.9. LIST Command . . . . . . . . . . . . . . . . . . . . 45 135 6.3.10. NAMESPACE Command . . . . . . . . . . . . . . . . . . 63 136 6.3.11. STATUS Command . . . . . . . . . . . . . . . . . . . 67 137 6.3.12. APPEND Command . . . . . . . . . . . . . . . . . . . 68 138 6.3.13. IDLE Command . . . . . . . . . . . . . . . . . . . . 71 139 6.4. Client Commands - Selected State . . . . . . . . . . . . 73 140 6.4.1. CLOSE Command . . . . . . . . . . . . . . . . . . . . 74 141 6.4.2. UNSELECT Command . . . . . . . . . . . . . . . . . . 74 142 6.4.3. EXPUNGE Command . . . . . . . . . . . . . . . . . . . 75 143 6.4.4. SEARCH Command . . . . . . . . . . . . . . . . . . . 75 144 6.4.5. FETCH Command . . . . . . . . . . . . . . . . . . . . 87 145 6.4.6. STORE Command . . . . . . . . . . . . . . . . . . . . 92 146 6.4.7. COPY Command . . . . . . . . . . . . . . . . . . . . 93 147 6.4.8. MOVE Command . . . . . . . . . . . . . . . . . . . . 94 148 6.4.9. UID Command . . . . . . . . . . . . . . . . . . . . . 96 149 6.5. Client Commands - Experimental/Expansion . . . . . . . . 97 150 7. Server Responses . . . . . . . . . . . . . . . . . . . . . . 98 151 7.1. Server Responses - Status Responses . . . . . . . . . . . 99 152 7.1.1. OK Response . . . . . . . . . . . . . . . . . . . . . 107 153 7.1.2. NO Response . . . . . . . . . . . . . . . . . . . . . 107 154 7.1.3. BAD Response . . . . . . . . . . . . . . . . . . . . 108 155 7.1.4. PREAUTH Response . . . . . . . . . . . . . . . . . . 108 156 7.1.5. BYE Response . . . . . . . . . . . . . . . . . . . . 109 157 7.2. Server Responses - Server and Mailbox Status . . . . . . 109 158 7.2.1. The ENABLED Response . . . . . . . . . . . . . . . . 109 159 7.2.2. CAPABILITY Response . . . . . . . . . . . . . . . . . 110 160 7.2.3. LIST Response . . . . . . . . . . . . . . . . . . . . 111 161 7.2.4. NAMESPACE Response . . . . . . . . . . . . . . . . . 114 162 7.2.5. STATUS Response . . . . . . . . . . . . . . . . . . . 115 163 7.2.6. ESEARCH Response . . . . . . . . . . . . . . . . . . 115 164 7.2.7. FLAGS Response . . . . . . . . . . . . . . . . . . . 116 165 7.3. Server Responses - Mailbox Size . . . . . . . . . . . . . 116 166 7.3.1. EXISTS Response . . . . . . . . . . . . . . . . . . . 116 167 7.4. Server Responses - Message Status . . . . . . . . . . . . 116 168 7.4.1. EXPUNGE Response . . . . . . . . . . . . . . . . . . 117 169 7.4.2. FETCH Response . . . . . . . . . . . . . . . . . . . 117 170 7.5. Server Responses - Command Continuation Request . . . . . 123 171 8. Sample IMAP4rev2 connection . . . . . . . . . . . . . . . . . 124 172 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 125 173 10. Author's Note . . . . . . . . . . . . . . . . . . . . . . . . 143 174 11. Security Considerations . . . . . . . . . . . . . . . . . . . 143 175 11.1. STARTTLS Security Considerations . . . . . . . . . . . . 143 176 11.2. COPYUID and APPENDUID response codes . . . . . . . . . . 144 177 11.3. LIST command and Other Users' namespace . . . . . . . . 144 178 11.4. Other Security Considerations . . . . . . . . . . . . . 145 179 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 145 180 12.1. Updates to IMAP4 Capabilities registry . . . . . . . . . 146 181 12.2. GSSAPI/SASL service name . . . . . . . . . . . . . . . . 146 182 12.3. LIST Selection Options, LIST Return Options, LIST 183 extended data items . . . . . . . . . . . . . . . . . . 146 184 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 147 185 13.1. Normative References . . . . . . . . . . . . . . . . . . 147 186 13.2. Informative References (related protocols) . . . . . . . 150 187 13.3. Informative References (historical aspects of IMAP and 188 related protocols) . . . . . . . . . . . . . . . . . . . 152 189 Appendix A. Backward compatibility with IMAP4rev1 . . . . . . . 152 190 A.1. Mailbox International Naming Convention for compatibility 191 with IMAP4rev1 . . . . . . . . . . . . . . . . . . . . . 153 192 Appendix B. Backward compatibility with BINARY extension . . . . 155 193 Appendix C. Backward compatibility with LIST-EXTENDED extension 155 194 Appendix D. 63 bit body part and message sizes . . . . . . . . . 155 195 Appendix E. Changes from RFC 3501 / IMAP4rev1 . . . . . . . . . 155 196 Appendix F. Other Recommended IMAP Extensions . . . . . . . . . 157 197 Appendix G. Acknowledgement . . . . . . . . . . . . . . . . . . 158 198 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 199 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 163 201 1. How to Read This Document 203 1.1. Organization of This Document 205 This document is written from the point of view of the implementor of 206 an IMAP4rev2 client or server. Beyond the protocol overview in 207 section 2, it is not optimized for someone trying to understand the 208 operation of the protocol. The material in sections 3 through 5 209 provides the general context and definitions with which IMAP4rev2 210 operates. 212 Sections 6, 7, and 9 describe the IMAP commands, responses, and 213 syntax, respectively. The relationships among these are such that it 214 is almost impossible to understand any of them separately. In 215 particular, do not attempt to deduce command syntax from the command 216 section alone; instead refer to the Formal Syntax (Section 9). 218 1.2. Conventions Used in This Document 220 "Conventions" are basic principles or procedures. Document 221 conventions are noted in this section. 223 In examples, "C:" and "S:" indicate lines sent by the client and 224 server respectively. Note that each line includes the terminating 225 CRLF. 227 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 228 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 229 "OPTIONAL" in this document are to be interpreted as described in BCP 230 14 [RFC2119] [RFC8174] when, and only when, they appear in all 231 capitals, as shown here. 233 The word "can" (not "may") is used to refer to a possible 234 circumstance or situation, as opposed to an optional facility of the 235 protocol. 237 "User" is used to refer to a human user, whereas "client" refers to 238 the software being run by the user. 240 "Connection" refers to the entire sequence of client/server 241 interaction from the initial establishment of the network connection 242 until its termination. 244 "Session" refers to the sequence of client/server interaction from 245 the time that a mailbox is selected (SELECT or EXAMINE command) until 246 the time that selection ends (SELECT or EXAMINE of another mailbox, 247 CLOSE command, UNSELECT command, or connection termination). 249 Characters are 8-bit UTF-8 (of which 7-bit US-ASCII is a subset) 250 unless otherwise specified. Other character sets are indicated using 251 a "CHARSET", as described in [MIME-IMT] and defined in [CHARSET]. 252 CHARSETs have important additional semantics in addition to defining 253 character set; refer to these documents for more detail. 255 There are several protocol conventions in IMAP. These refer to 256 aspects of the specification which are not strictly part of the IMAP 257 protocol, but reflect generally-accepted practice. Implementations 258 need to be aware of these conventions, and avoid conflicts whether or 259 not they implement the convention. For example, "&" may not be used 260 as a hierarchy delimiter since it conflicts with the Mailbox 261 International Naming Convention, and other uses of "&" in mailbox 262 names are impacted as well. 264 1.3. Special Notes to Implementors 266 Implementors of the IMAP protocol are strongly encouraged to read the 267 IMAP implementation recommendations document [IMAP-IMPLEMENTATION] in 268 conjunction with this document, to help understand the intricacies of 269 this protocol and how best to build an interoperable product. 271 IMAP4rev2 is designed to be upwards compatible from the IMAP4rev1, 272 the [IMAP2] and unpublished IMAP2bis protocols. IMAP4rev2 is largely 273 compatible with the IMAP4rev1 protocol described in RFC 3501 and the 274 IMAP4 protocol described in RFC 1730; the exception being in certain 275 facilities added in RFC 1730 and RFC 3501 that proved problematic and 276 were subsequently removed or replaced by better alternatives. In the 277 course of the evolution of IMAP4rev2, some aspects in the earlier 278 protocols have become obsolete. Obsolete commands, responses, and 279 data formats which an IMAP4rev2 implementation can encounter when 280 used with an earlier implementation are described in Appendix E, 281 Appendix A and [IMAP-OBSOLETE]. IMAP4rev2 supports 63bit body part 282 and message sizes. IMAP4rev2 compatibility with BINARY and LIST- 283 EXTENDED IMAP extensions are described in Appendix B and Appendix C 284 respectively. 286 Other compatibility issues with IMAP2bis, the most common variant of 287 the earlier protocol, are discussed in [IMAP-COMPAT]. A full 288 discussion of compatibility issues with rare (and presumed extinct) 289 variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is 290 primarily of historical interest. 292 IMAP was originally developed for the older [RFC-822] standard, and 293 as a consequence several fetch items in IMAP incorporate "RFC822" in 294 their name. In all cases, "RFC822" should be interpreted as a 295 reference to the updated [RFC-5322] standard. 297 2. Protocol Overview 299 2.1. Link Level 301 The IMAP4rev2 protocol assumes a reliable data stream such as that 302 provided by TCP. When TCP is used, an IMAP4rev2 server listens on 303 port 143 or port 993 (IMAP-over-TLS). 305 2.2. Commands and Responses 307 An IMAP4rev2 connection consists of the establishment of a client/ 308 server network connection, an initial greeting from the server, and 309 client/server interactions. These client/server interactions consist 310 of a client command, server data, and a server completion result 311 response. 313 All interactions transmitted by client and server are in the form of 314 lines, that is, strings that end with a CRLF. The protocol receiver 315 of an IMAP4rev2 client or server is either reading a line, or is 316 reading a sequence of octets with a known count followed by a line. 318 2.2.1. Client Protocol Sender and Server Protocol Receiver 320 The client command begins an operation. Each client command is 321 prefixed with an identifier (typically a short alphanumeric string, 322 e.g., A0001, A0002, etc.) called a "tag". A different tag is 323 generated by the client for each command. (More formally: the client 324 SHOULD generate a unique tag for every command, but a server MUST 325 accept tag reuse.) 327 Clients MUST follow the syntax outlined in this specification 328 strictly. It is a syntax error to send a command with missing or 329 extraneous spaces or arguments. 331 There are two cases in which a line from the client does not 332 represent a complete command. In one case, a command argument is 333 quoted with an octet count (see the description of literal in 334 Section 4.3); in the other case, the command arguments require server 335 feedback (see the AUTHENTICATE command in Section 6.2.2). In either 336 case, the server sends a command continuation request response if it 337 is ready for the octets (if appropriate) and the remainder of the 338 command. This response is prefixed with the token "+". 340 Note: If instead, the server detected an error in the command, it 341 sends a BAD completion response with a tag matching the command 342 (as described below) to reject the command and prevent the client 343 from sending any more of the command. 345 It is also possible for the server to send a completion response 346 for some other command (if multiple commands are in progress), or 347 untagged data. In either case, the command continuation request 348 is still pending; the client takes the appropriate action for the 349 response, and reads another response from the server. In all 350 cases, the client MUST send a complete command (including 351 receiving all command continuation request responses and command 352 continuations for the command) before initiating a new command. 354 The protocol receiver of an IMAP4rev2 server reads a command line 355 from the client, parses the command and its arguments, and transmits 356 server data and a server command completion result response. 358 2.2.2. Server Protocol Sender and Client Protocol Receiver 360 Data transmitted by the server to the client and status responses 361 that do not indicate command completion are prefixed with the token 362 "*", and are called untagged responses. 364 Server data MAY be sent as a result of a client command, or MAY be 365 sent unilaterally by the server. There is no syntactic difference 366 between server data that resulted from a specific command and server 367 data that were sent unilaterally. 369 The server completion result response indicates the success or 370 failure of the operation. It is tagged with the same tag as the 371 client command which began the operation. Thus, if more than one 372 command is in progress, the tag in a server completion response 373 identifies the command to which the response applies. There are 374 three possible server completion responses: OK (indicating success), 375 NO (indicating failure), or BAD (indicating a protocol error such as 376 unrecognized command or command syntax error). 378 Servers SHOULD enforce the syntax outlined in this specification 379 strictly. Any client command with a protocol syntax error, including 380 (but not limited to) missing or extraneous spaces or arguments, 381 SHOULD be rejected, and the client given a BAD server completion 382 response. 384 The protocol receiver of an IMAP4rev2 client reads a response line 385 from the server. It then takes action on the response based upon the 386 first token of the response, which can be a tag, a "*", or a "+". 388 A client MUST be prepared to accept any server response at all times. 389 This includes server data that was not requested. Server data SHOULD 390 be recorded, so that the client can reference its recorded copy 391 rather than sending a command to the server to request the data. In 392 the case of certain server data, the data MUST be recorded. 394 This topic is discussed in greater detail in the Server Responses 395 section. 397 2.3. Message Attributes 399 In addition to message text, each message has several attributes 400 associated with it. These attributes can be retrieved individually 401 or in conjunction with other attributes or message texts. 403 2.3.1. Message Numbers 405 Messages in IMAP4rev2 are accessed by one of two numbers; the unique 406 identifier or the message sequence number. 408 2.3.1.1. Unique Identifier (UID) Message Attribute 410 A UID is an unsigned non-zero 32-bit value assigned to each message, 411 which when used with the unique identifier validity value (see below) 412 forms a 64-bit value that MUST NOT refer to any other message in the 413 mailbox or any subsequent mailbox with the same name forever. Unique 414 identifiers are assigned in a strictly ascending fashion in the 415 mailbox; as each message is added to the mailbox it is assigned a 416 higher UID than the message(s) which were added previously. Unlike 417 message sequence numbers, unique identifiers are not necessarily 418 contiguous. 420 The unique identifier of a message MUST NOT change during the 421 session, and SHOULD NOT change between sessions. Any change of 422 unique identifiers between sessions MUST be detectable using the 423 UIDVALIDITY mechanism discussed below. Persistent unique identifiers 424 are required for a client to resynchronize its state from a previous 425 session with the server (e.g., disconnected or offline access clients 426 [IMAP-MODEL]); this is discussed further in [IMAP-DISC]. 428 Associated with every mailbox are two 32-bit unsigned non-zero values 429 which aid in unique identifier handling: the next unique identifier 430 value (UIDNEXT) and the unique identifier validity value 431 (UIDVALIDITY). 433 The next unique identifier value is the predicted value that will be 434 assigned to a new message in the mailbox. Unless the unique 435 identifier validity also changes (see below), the next unique 436 identifier value MUST have the following two characteristics. First, 437 the next unique identifier value MUST NOT change unless new messages 438 are added to the mailbox; and second, the next unique identifier 439 value MUST change whenever new messages are added to the mailbox, 440 even if those new messages are subsequently expunged. 442 Note: The next unique identifier value is intended to provide a 443 means for a client to determine whether any messages have been 444 delivered to the mailbox since the previous time it checked this 445 value. It is not intended to provide any guarantee that any 446 message will have this unique identifier. A client can only 447 assume, at the time that it obtains the next unique identifier 448 value, that messages arriving after that time will have a UID 449 greater than or equal to that value. 451 The unique identifier validity value is sent in a UIDVALIDITY 452 response code in an OK untagged response at mailbox selection time. 453 If unique identifiers from an earlier session fail to persist in this 454 session, the unique identifier validity value MUST be greater than 455 the one used in the earlier session. A good UIDVALIDITY value to use 456 is a 32-bit representation of the current date/time when the value is 457 assigned: this ensures that the value is unique and always increases. 458 Another possible alternative is a global counter that gets 459 incremented every time a mailbox is created. 461 Note: Ideally, unique identifiers SHOULD persist at all times. 462 Although this specification recognizes that failure to persist can 463 be unavoidable in certain server environments, it strongly 464 encourages message store implementation techniques that avoid this 465 problem. For example: 467 1. Unique identifiers MUST be strictly ascending in the mailbox 468 at all times. If the physical message store is re-ordered by 469 a non-IMAP agent, this requires that the unique identifiers in 470 the mailbox be regenerated, since the former unique 471 identifiers are no longer strictly ascending as a result of 472 the re-ordering. 474 2. If the message store has no mechanism to store unique 475 identifiers, it must regenerate unique identifiers at each 476 session, and each session must have a unique UIDVALIDITY 477 value. 479 3. If the mailbox is deleted/renamed and a new mailbox with the 480 same name is created at a later date, the server must either 481 keep track of unique identifiers from the previous instance of 482 the mailbox, or it must assign a new UIDVALIDITY value to the 483 new instance of the mailbox. 485 4. The combination of mailbox name, UIDVALIDITY, and UID must 486 refer to a single immutable (or expunged) message on that 487 server forever. In particular, the internal date, [RFC-5322] 488 size, envelope, body structure, and message texts (all 489 BODY[...] fetch data items) must never change. This does not 490 include message numbers, nor does it include attributes that 491 can be set by a STORE command (e.g., FLAGS). When a message 492 is expunged, its UID MUST NOT be reused under the same 493 UIDVALIDITY value. 495 2.3.1.2. Message Sequence Number Message Attribute 497 A Message Sequence Number is a relative position from 1 to the number 498 of messages in the mailbox. This position MUST be ordered by 499 ascending unique identifier. As each new message is added, it is 500 assigned a message sequence number that is 1 higher than the number 501 of messages in the mailbox before that new message was added. 503 Message sequence numbers can be reassigned during the session. For 504 example, when a message is permanently removed (expunged) from the 505 mailbox, the message sequence number for all subsequent messages is 506 decremented. The number of messages in the mailbox is also 507 decremented. Similarly, a new message can be assigned a message 508 sequence number that was once held by some other message prior to an 509 expunge. 511 In addition to accessing messages by relative position in the 512 mailbox, message sequence numbers can be used in mathematical 513 calculations. For example, if an untagged "11 EXISTS" is received, 514 and previously an untagged "8 EXISTS" was received, three new 515 messages have arrived with message sequence numbers of 9, 10, and 11. 516 Another example, if message 287 in a 523 message mailbox has UID 517 12345, there are exactly 286 messages which have lesser UIDs and 236 518 messages which have greater UIDs. 520 2.3.2. Flags Message Attribute 522 A message has associated with it a list of zero or more named tokens, 523 known as "flags". A flag is set by its addition to this list, and is 524 cleared by its removal. There are two types of flags in IMAP4rev2: 525 system flags, and keywords. A flag of either type can also be 526 permanent or session-only. 528 A system flag is a flag name that is pre-defined in this 529 specification and begins with "\". Certain system flags (\Deleted 530 and \Seen) have special semantics described elsewhere in this 531 document. The currently-defined system flags are: 533 \Seen Message has been read 535 \Answered Message has been answered 537 \Flagged Message is "flagged" for urgent/special attention 539 \Deleted Message is "deleted" for removal by later EXPUNGE 541 \Draft Message has not completed composition (marked as a draft). 543 \Recent This flag was in use in IMAP4rev1 and is now deprecated. 545 A keyword is defined by the server implementation. Keywords do not 546 begin with "\". Servers MAY permit the client to define new keywords 547 in the mailbox (see the description of the PERMANENTFLAGS response 548 code for more information). Some keywords that start with "$" are 549 also defined in this specification. 551 This document defines several keywords that were not originally 552 defined in RFC 3501, but which were found to be useful by client 553 implementations. These keywords SHOULD be supported (i.e. allowed in 554 SEARCH, allowed and preserved in APPEND, COPY, MOVE commands) by 555 server implementations: 557 $Forwarded Message has been forwarded to another email address, 558 embedded within or attached to a new message. An email client 559 sets this keyword when it successfully forwards the message to 560 another email address. Typical usage of this keyword is to show a 561 different (or additional) icon for a message that has been 562 forwarded. Once set, the flag SHOULD NOT be cleared. 564 $MDNSent Message Disposition Notification [RFC8098] was generated 565 and sent for this message. See [RFC3503] for more details on how 566 this keyword is used. 568 $Junk The user (or a delivery agent on behalf of the user) may 569 choose to mark a message as definitely containing junk ($Junk; see 570 also the related keyword $NotJunk). The $Junk keyword can be used 571 to mark (and potentially move/delete messages later), group or 572 hide undesirable messages. See [IMAP-KEYWORDS-REG] for more 573 information. 575 $NotJunk The user (or a delivery agent on behalf of the user) may 576 choose to mark a message as definitely not containing junk 577 ($NotJunk; see also the related keyword $Junk). The $NotJunk 578 keyword can be used to mark, group or show messages that the user 579 wants to see. See [IMAP-KEYWORDS-REG] for more information. 581 $Phishing The $Phishing keyword can be used by a delivery agent to 582 mark a message as highly likely to be a phishing email. An email 583 that's determined to be a phishing email by the delivery agent 584 should also be considered a junk email and have the appropriate 585 junk filtering applied, including setting the $Junk flag and 586 placing in the \Junk special-use mailbox (see Section 7.2.3) if 587 available. 588 If both the $Phishing flag and the $Junk flag are set, the user 589 agent should display an additional warning message to the user. 590 User agents should not use the term "phishing" in their warning 591 message as most users do not understand this term. Phrasing of 592 the form "this message may be trying to steal your personal 593 information" is recommended. Additionally the user agent may 594 display a warning when clicking on any hyperlinks within the 595 message. 596 The requirement for both $Phishing and $Junk to be set before a 597 user agent displays a warning is for better backwards 598 compatibility with existing clients that understand the $Junk flag 599 but not the $Phishing flag. This so that when an unextended 600 client removes the $Junk flag, an extended client will also show 601 the correct state. See [IMAP-KEYWORDS-REG] for more information. 603 $Junk and $NotJunk are mutually exclusive. If more than one of them 604 is set for a message, the client MUST treat this as if none of them 605 is set and SHOULD unset both of them on the IMAP server. 607 Other registered keywords can be found in the "IMAP and JMAP 608 Keywords" registry [IMAP-KEYWORDS-REG]. New keywords SHOULD be 609 registered in this registry using the procedure specified in 610 [RFC5788]. 612 A flag can be permanent or session-only on a per-flag basis. 613 Permanent flags are those which the client can add or remove from the 614 message flags permanently; that is, concurrent and subsequent 615 sessions will see any change in permanent flags. Changes to session 616 flags are valid only in that session. 618 2.3.3. Internal Date Message Attribute 620 An Internal Date message attribute is the internal date and time of 621 the message on the server. This is not the date and time in the 622 [RFC-5322] header, but rather a date and time which reflects when the 623 message was received. In the case of messages delivered via [SMTP], 624 this is the date and time of final delivery of the message as defined 625 by [SMTP]. In the case of messages delivered by the IMAP4rev2 COPY 626 or MOVE command, this SHOULD be the internal date and time of the 627 source message. In the case of messages delivered by the IMAP4rev2 628 APPEND command, this SHOULD be the date and time as specified in the 629 APPEND command description. All other cases are implementation 630 defined. 632 2.3.4. [RFC-5322] Size Message Attribute 634 An RFC 5322 size is the number of octets in the message, as expressed 635 in [RFC-5322] format. 637 2.3.5. Envelope Structure Message Attribute 639 An Envelope Structure is a parsed representation of the [RFC-5322] 640 header of the message. Note that the IMAP Envelope structure is not 641 the same as an [SMTP] envelope. 643 2.3.6. Body Structure Message Attribute 645 A Body Structure is a parsed representation of the [MIME-IMB] body 646 structure information of the message. 648 2.4. Message Texts 650 In addition to being able to fetch the full [RFC-5322] text of a 651 message, IMAP4rev2 permits the fetching of portions of the full 652 message text. Specifically, it is possible to fetch the [RFC-5322] 653 message header, [RFC-5322] message body, a [MIME-IMB] body part, or a 654 [MIME-IMB] header. 656 3. State and Flow Diagram 658 Once the connection between client and server is established, an 659 IMAP4rev2 connection is in one of four states. The initial state is 660 identified in the server greeting. Most commands are only valid in 661 certain states. It is a protocol error for the client to attempt a 662 command while the connection is in an inappropriate state, and the 663 server will respond with a BAD or NO (depending upon server 664 implementation) command completion result. 666 3.1. Not Authenticated State 668 In the not authenticated state, the client MUST supply authentication 669 credentials before most commands will be permitted. This state is 670 entered when a connection starts unless the connection has been pre- 671 authenticated. 673 3.2. Authenticated State 675 In the authenticated state, the client is authenticated and MUST 676 select a mailbox to access before commands that affect messages will 677 be permitted. This state is entered when a pre-authenticated 678 connection starts, when acceptable authentication credentials have 679 been provided, after an error in selecting a mailbox, or after a 680 successful CLOSE command. 682 3.3. Selected State 684 In a selected state, a mailbox has been selected to access. This 685 state is entered when a mailbox has been successfully selected. 687 3.4. Logout State 689 In the logout state, the connection is being terminated. This state 690 can be entered as a result of a client request (via the LOGOUT 691 command) or by unilateral action on the part of either the client or 692 server. 694 If the client requests the logout state, the server MUST send an 695 untagged BYE response and a tagged OK response to the LOGOUT command 696 before the server closes the connection; and the client MUST read the 697 tagged OK response to the LOGOUT command before the client closes the 698 connection. 700 A server SHOULD NOT unilaterally close the connection without sending 701 an untagged BYE response that contains the reason for having done so. 702 A client SHOULD NOT unilaterally close the connection, and instead 703 SHOULD issue a LOGOUT command. If the server detects that the client 704 has unilaterally closed the connection, the server MAY omit the 705 untagged BYE response and simply close its connection. 707 +----------------------+ 708 |connection established| 709 +----------------------+ 710 || 711 \/ 712 +--------------------------------------+ 713 | server greeting | 714 +--------------------------------------+ 715 || (1) || (2) || (3) 716 \/ || || 717 +-----------------+ || || 718 |Not Authenticated| || || 719 +-----------------+ || || 720 || (7) || (4) || || 721 || \/ \/ || 722 || +----------------+ || 723 || | Authenticated |<=++ || 724 || +----------------+ || || 725 || || (7) || (5) || (6) || 726 || || \/ || || 727 || || +--------+ || || 728 || || |Selected|==++ || 729 || || +--------+ || 730 || || || (7) || 731 \/ \/ \/ \/ 732 +--------------------------------------+ 733 | Logout | 734 +--------------------------------------+ 735 || 736 \/ 737 +-------------------------------+ 738 |both sides close the connection| 739 +-------------------------------+ 741 (1) connection without pre-authentication (OK greeting) 742 (2) pre-authenticated connection (PREAUTH greeting) 743 (3) rejected connection (BYE greeting) 744 (4) successful LOGIN or AUTHENTICATE command 745 (5) successful SELECT or EXAMINE command 746 (6) CLOSE command, unsolicited CLOSED response code or 747 failed SELECT or EXAMINE command 748 (7) LOGOUT command, server shutdown, or connection closed 750 4. Data Formats 752 IMAP4rev2 uses textual commands and responses. Data in IMAP4rev2 can 753 be in one of several forms: atom, number, string, parenthesized list, 754 or NIL. Note that a particular data item may take more than one 755 form; for example, a data item defined as using "astring" syntax may 756 be either an atom or a string. 758 4.1. Atom 760 An atom consists of one or more non-special characters. 762 4.1.1. Sequence set and UID set 764 A set of messages can be referenced by a sequence set containing 765 either message sequence numbers or unique identifiers. See Section 9 766 for details. Sequence sets can contain ranges (e.g. "5:50"), an 767 enumeration of specific message/UID numbers, a special symbol "*", or 768 a combination of the above. 770 A "UID set" is similar to the sequence set of unique identifiers; 771 however, the "*" value for a sequence number is not permitted. 773 4.2. Number 775 A number consists of one or more digit characters, and represents a 776 numeric value. 778 4.3. String 780 A string is in one of three forms: synchonizing literal, non- 781 synchronizing literal or quoted string. The synchronizing literal 782 form is the general form of string. The non-synchronizing literal 783 form is also the general form, but has length limitation. The quoted 784 string form is an alternative that avoids the overhead of processing 785 a literal at the cost of limitations of characters which may be used. 787 When the distinction between synchronizing and non-synchronizing 788 literals is not important, this document just uses the term 789 "literal". 791 A synchronizing literal is a sequence of zero or more octets 792 (including CR and LF), prefix-quoted with an octet count in the form 793 of an open brace ("{"), the number of octets, close brace ("}"), and 794 CRLF. In the case of synchronizing literals transmitted from server 795 to client, the CRLF is immediately followed by the octet data. In 796 the case of synchronizing literals transmitted from client to server, 797 the client MUST wait to receive a command continuation request 798 (described later in this document) before sending the octet data (and 799 the remainder of the command). 801 The non-synchronizing literal is an alternative form of synchronizing 802 literal, and it may appear in communication from client to server 803 instead of the synchonizing form of literal. The non-synchronizing 804 literal form MUST NOT be sent from server to client. The non- 805 synchronizing literal is distinguished from the synchronizing literal 806 by having a plus ("+") between the octet count and the closing brace 807 ("}"). The server does not generate a command continuation request 808 in response to a non-synchronizing literal, and clients are not 809 required to wait before sending the octets of a non- synchronizing 810 literal. Non-synchronizing literals MUST NOT be larger than 4096 811 octets. Any literal larger than 4096 bytes MUST be sent as a 812 synchronizing literal. (Non-synchronizing literals defined in this 813 document are the same as non-synchronizing literals defined by the 814 LITERAL- extension from [RFC7888]. See that document for details on 815 how to handle invalid non-synchronizing literals longer than 4096 816 octets and for interaction with other IMAP extensions.) 818 A quoted string is a sequence of zero or more Unicode characters, 819 excluding CR and LF, encoded in UTF-8, with double quote (<">) 820 characters at each end. 822 The empty string is represented as "" (a quoted string with zero 823 characters between double quotes), as {0} followed by CRLF (a 824 synchronizing literal with an octet count of 0) or as {0+} followed 825 by CRLF (a non-synchronizing literal with an octet count of 0). 827 Note: Even if the octet count is 0, a client transmitting a 828 synchronizing literal MUST wait to receive a command continuation 829 request. 831 4.3.1. 8-bit and Binary Strings 833 8-bit textual and binary mail is supported through the use of a 834 [MIME-IMB] content transfer encoding. IMAP4rev2 implementations MAY 835 transmit 8-bit or multi-octet characters in literals, but SHOULD do 836 so only when the [CHARSET] is identified. 838 IMAP4rev2 is compatible with [I18N-HDRS]. As a result, the 839 identified charset for header-field values with 8-bit content is 840 UTF-8 [UTF-8]. IMAP4rev2 implementations MUST accept and MAY 841 transmit [UTF-8] text in quoted-strings as long as the string does 842 not contain NUL, CR, or LF. This differs from IMAP4rev1 843 implementations. 845 Although a BINARY content transfer encoding is defined, unencoded 846 binary strings are not permitted, unless returned in a in 847 response to BINARY.PEEK[]<> or 848 BINARY[]<> FETCH data item. A "binary 849 string" is any string with NUL characters. A string with an 850 excessive amount of CTL characters MAY also be considered to be 851 binary. Unless returned in response to BINARY.PEEK[...]/BINARY[...] 852 FETCH, client and server implementations MUST encode binary data into 853 a textual form, such as BASE64, before transmitting the data. 855 4.4. Parenthesized List 857 Data structures are represented as a "parenthesized list"; a sequence 858 of data items, delimited by space, and bounded at each end by 859 parentheses. A parenthesized list can contain other parenthesized 860 lists, using multiple levels of parentheses to indicate nesting. 862 The empty list is represented as () -- a parenthesized list with no 863 members. 865 4.5. NIL 867 The special form "NIL" represents the non-existence of a particular 868 data item that is represented as a string or parenthesized list, as 869 distinct from the empty string "" or the empty parenthesized list (). 871 Note: NIL is never used for any data item which takes the form of 872 an atom. For example, a mailbox name of "NIL" is a mailbox named 873 NIL as opposed to a non-existent mailbox name. This is because 874 mailbox uses "astring" syntax which is an atom or a string. 875 Conversely, an addr-name of NIL is a non-existent personal name, 876 because addr-name uses "nstring" syntax which is NIL or a string, 877 but never an atom. 879 Examples: 881 The following LIST response: 883 * LIST () "/" NIL 885 is equivalent to: 886 * LIST () "/" "NIL" 888 as LIST response ABNF is using astring for mailbox name. 890 However, the following response 892 * FETCH 1 (BODY[1] NIL) 894 is not equivalent to: 895 * FETCH 1 (BODY[1] "NIL") 896 The former means absence of the body part, while the latter 897 means that it contains literal sequence of characters "NIL". 899 5. Operational Considerations 901 The following rules are listed here to ensure that all IMAP4rev2 902 implementations interoperate properly. 904 5.1. Mailbox Naming 906 In IMAP4rev2, Mailbox names are encoded in Net-Unicode [NET-UNICODE] 907 (this differs from IMAP4rev1). Client implementations MAY attempt to 908 create Net-Unicode mailbox names, and MUST interpret any 8-bit 909 mailbox names returned by LIST as [NET-UNICODE]. Server 910 implementations MUST prohibit the creation of 8-bit mailbox names 911 that do not comply with Net-Unicode. However, servers MAY accept a 912 de-normalized UTF-8 mailbox name and convert it to Unicode 913 normalization form "NFC" (as per Net-Unicode requirements) prior to 914 mailbox creation. Servers that choose to accept such de-normalized 915 UTF-8 mailbox names MUST accept them in all IMAP commands that have a 916 mailbox name parameter. In particular SELECT must open the 917 same mailbox that was successfully created with CREATE , even 918 if is a de-normalized UTF-8 mailbox name. 920 The case-insensitive mailbox name INBOX is a special name reserved to 921 mean "the primary mailbox for this user on this server". (Note that 922 this special name may not exist on some servers for some users, for 923 example if the user has no access to personal namespace.) The 924 interpretation of all other names is implementation-dependent. 926 In particular, this specification takes no position on case 927 sensitivity in non-INBOX mailbox names. Some server implementations 928 are fully case-sensitive in ASCII range; others preserve case of a 929 newly-created name but otherwise are case-insensitive; and yet others 930 coerce names to a particular case. Client implementations must be 931 able to interact with any of these. 933 There are certain client considerations when creating a new mailbox 934 name: 936 1. Any character which is one of the atom-specials (see the Formal 937 Syntax in Section 9) will require that the mailbox name be 938 represented as a quoted string or literal. 940 2. CTL and other non-graphic characters are difficult to represent 941 in a user interface and are best avoided. Servers MAY refuse to 942 create mailbox names containing Unicode CTL characters. 944 3. Although the list-wildcard characters ("%" and "*") are valid in 945 a mailbox name, it is difficult to use such mailbox names with 946 the LIST command due to the conflict with wildcard 947 interpretation. 949 4. Usually, a character (determined by the server implementation) is 950 reserved to delimit levels of hierarchy. 952 5. Two characters, "#" and "&", have meanings by convention, and 953 should be avoided except when used in that convention. See 954 Section 5.1.2.1 and Appendix A.1 respectively. 956 5.1.1. Mailbox Hierarchy Naming 958 If it is desired to export hierarchical mailbox names, mailbox names 959 MUST be left-to-right hierarchical using a single character to 960 separate levels of hierarchy. The same hierarchy separator character 961 is used for all levels of hierarchy within a single name. 963 5.1.2. Namespaces 965 Personal Namespace: A namespace that the server considers within the 966 personal scope of the authenticated user on a particular connection. 967 Typically, only the authenticated user has access to mailboxes in 968 their Personal Namespace. It is the part of the namespace that 969 belongs to the user that is allocated for mailboxes. If an INBOX 970 exists for a user, it MUST appear within the user's personal 971 namespace. In the typical case, there SHOULD be only one Personal 972 Namespace on a server. 974 Other Users' Namespace: A namespace that consists of mailboxes from 975 the Personal Namespaces of other users. To access mailboxes in the 976 Other Users' Namespace, the currently authenticated user MUST be 977 explicitly granted access rights. For example, it is common for a 978 manager to grant to their secretary access rights to their mailbox. 979 In the typical case, there SHOULD be only one Other Users' Namespace 980 on a server. 982 Shared Namespace: A namespace that consists of mailboxes that are 983 intended to be shared amongst users and do not exist within a user's 984 Personal Namespace. 986 The namespaces a server uses MAY differ on a per-user basis. 988 5.1.2.1. Historic Mailbox Namespace Naming Convention 990 By convention, the first hierarchical element of any mailbox name 991 which begins with "#" identifies the "namespace" of the remainder of 992 the name. This makes it possible to disambiguate between different 993 types of mailbox stores, each of which have their own namespaces. 995 For example, implementations which offer access to USENET 996 newsgroups MAY use the "#news" namespace to partition the USENET 997 newsgroup namespace from that of other mailboxes. Thus, the 998 comp.mail.misc newsgroup would have a mailbox name of 999 "#news.comp.mail.misc", and the name "comp.mail.misc" can refer to 1000 a different object (e.g., a user's private mailbox). 1002 Namespaces that include the "#" character are not IMAP URL [IMAP-URL] 1003 friendly requiring the "#" character to be represented as %23 when 1004 within URLs. As such, server implementors MAY instead consider using 1005 namespace prefixes that do not contain the "#" character. 1007 5.1.2.2. Common namespace models 1009 Previous version of this protocol does not define a default server 1010 namespace. Two common namespace models have evolved: 1012 The "Personal Mailbox" model, in which the default namespace that is 1013 presented consists of only the user's personal mailboxes. To access 1014 shared mailboxes, the user must use an escape mechanism to reach 1015 another namespace. 1017 The "Complete Hierarchy" model, in which the default namespace that 1018 is presented includes the user's personal mailboxes along with any 1019 other mailboxes they have access to. 1021 5.2. Mailbox Size and Message Status Updates 1023 At any time, a server can send data that the client did not request. 1024 Sometimes, such behavior is required by this specification and/or 1025 extensions. For example, agents other than the server MAY add 1026 messages to the mailbox (e.g., new message delivery), change the 1027 flags of the messages in the mailbox (e.g., simultaneous access to 1028 the same mailbox by multiple agents), or even remove messages from 1029 the mailbox. A server MUST send mailbox size updates automatically 1030 if a mailbox size change is observed during the processing of a 1031 command. A server SHOULD send message flag updates automatically, 1032 without requiring the client to request such updates explicitly. 1034 Special rules exist for server notification of a client about the 1035 removal of messages to prevent synchronization errors; see the 1036 description of the EXPUNGE response (Section 7.4.1) for more detail. 1037 In particular, it is NOT permitted to send an EXISTS response that 1038 would reduce the number of messages in the mailbox; only the EXPUNGE 1039 response can do this. 1041 Regardless of what implementation decisions a client makes on 1042 remembering data from the server, a client implementation MUST record 1043 mailbox size updates. It MUST NOT assume that any command after the 1044 initial mailbox selection will return the size of the mailbox. 1046 5.3. Response when no Command in Progress 1048 Server implementations are permitted to send an untagged response 1049 (except for EXPUNGE) while there is no command in progress. Server 1050 implementations that send such responses MUST deal with flow control 1051 considerations. Specifically, they MUST either (1) verify that the 1052 size of the data does not exceed the underlying transport's available 1053 window size, or (2) use non-blocking writes. 1055 5.4. Autologout Timer 1057 If a server has an inactivity autologout timer that applies to 1058 sessions after authentication, the duration of that timer MUST be at 1059 least 30 minutes. The receipt of any command from the client during 1060 that interval resets the autologout timer. 1062 Note that this specification doesn't have any restrictions on 1063 autologout timer used before successful client authentication. In 1064 particular, servers are allowed to use shorted pre-authentication 1065 timer to protect themselves from Denial of Service attacks. 1067 5.5. Multiple Commands in Progress (Command Pipelining) 1069 The client MAY send another command without waiting for the 1070 completion result response of a command, subject to ambiguity rules 1071 (see below) and flow control constraints on the underlying data 1072 stream. Similarly, a server MAY begin processing another command 1073 before processing the current command to completion, subject to 1074 ambiguity rules. However, any command continuation request responses 1075 and command continuations MUST be negotiated before any subsequent 1076 command is initiated. 1078 The exception is if an ambiguity would result because of a command 1079 that would affect the results of other commands. If the server 1080 detects a possible ambiguity, it MUST execute commands to completion 1081 in the order given by the client. 1083 The most obvious example of ambiguity is when a command would affect 1084 the results of another command, e.g., a FETCH of a message's flags 1085 and a STORE of that same message's flags. 1087 A non-obvious ambiguity occurs with commands that permit an untagged 1088 EXPUNGE response (commands other than FETCH, STORE, and SEARCH), 1089 since an untagged EXPUNGE response can invalidate sequence numbers in 1090 a subsequent command. This is not a problem for FETCH, STORE, or 1091 SEARCH commands because servers are prohibited from sending EXPUNGE 1092 responses while any of those commands are in progress. Therefore, if 1093 the client sends any command other than FETCH, STORE, or SEARCH, it 1094 MUST wait for the completion result response before sending a command 1095 with message sequence numbers. 1097 Note: EXPUNGE responses are permitted while UID FETCH, UID STORE, 1098 and UID SEARCH are in progress. If the client sends a UID 1099 command, it MUST wait for a completion result response before 1100 sending a command which uses message sequence numbers (this may 1101 include UID SEARCH). Any message sequence numbers in an argument 1102 to UID SEARCH are associated with messages prior to the effect of 1103 any untagged EXPUNGE returned by the UID SEARCH. 1105 For example, the following non-waiting command sequences are invalid: 1107 FETCH + NOOP + STORE 1109 STORE + COPY + FETCH 1111 COPY + COPY 1113 The following are examples of valid non-waiting command sequences: 1115 FETCH + STORE + SEARCH + NOOP 1117 STORE + COPY + EXPUNGE 1119 UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting 1120 command sequence, depending upon whether or not the second UID 1121 SEARCH contains message sequence numbers. 1123 Use of SEARCH result variable (see Section 6.4.4.1) creates direct 1124 dependency between two commands. See Section 6.4.4.2 for more 1125 considerations about pipelining such dependent commands. 1127 6. Client Commands 1129 IMAP4rev2 commands are described in this section. Commands are 1130 organized by the state in which the command is permitted. Commands 1131 which are permitted in multiple states are listed in the minimum 1132 permitted state (for example, commands valid in authenticated and 1133 selected state are listed in the authenticated state commands). 1135 Command arguments, identified by "Arguments:" in the command 1136 descriptions below, are described by function, not by syntax. The 1137 precise syntax of command arguments is described in the Formal Syntax 1138 (Section 9). 1140 Some commands cause specific server responses to be returned; these 1141 are identified by "Responses:" in the command descriptions below. 1142 See the response descriptions in the Responses section (Section 7) 1143 for information on these responses, and the Formal Syntax (Section 9) 1144 for the precise syntax of these responses. It is possible for server 1145 data to be transmitted as a result of any command. Thus, commands 1146 that do not specifically require server data specify "no specific 1147 responses for this command" instead of "none". 1149 The "Result:" in the command description refers to the possible 1150 tagged status responses to a command, and any special interpretation 1151 of these status responses. 1153 The state of a connection is only changed by successful commands 1154 which are documented as changing state. A rejected command (BAD 1155 response) never changes the state of the connection or of the 1156 selected mailbox. A failed command (NO response) generally does not 1157 change the state of the connection or of the selected mailbox; the 1158 exception being the SELECT and EXAMINE commands. 1160 6.1. Client Commands - Any State 1162 The following commands are valid in any state: CAPABILITY, NOOP, and 1163 LOGOUT. 1165 6.1.1. CAPABILITY Command 1167 Arguments: none 1169 Responses: REQUIRED untagged response: CAPABILITY 1171 Result: OK - capability completed 1172 BAD - command unknown or arguments invalid 1174 The CAPABILITY command requests a listing of capabilities (e.g. 1175 extensions and/or modifications of server behaviour) that the server 1176 supports. The server MUST send a single untagged CAPABILITY response 1177 with "IMAP4rev2" as one of the listed capabilities before the 1178 (tagged) OK response. 1180 A capability name which begins with "AUTH=" indicates that the server 1181 supports that particular authentication mechanism as defined in 1182 [SASL]. All such names are, by definition, part of this 1183 specification. 1185 Other capability names refer to extensions, revisions, or amendments 1186 to this specification. See the documentation of the CAPABILITY 1187 response in Section 7.2.2 for additional information. No 1188 capabilities, beyond the base IMAP4rev2 set defined in this 1189 specification, are enabled without explicit client action to invoke 1190 the capability. 1192 Client and server implementations MUST implement the STARTTLS, 1193 LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) capabilities. 1194 See the Security Considerations (Section 11) for important 1195 information. 1197 Unless specified otherwise, all registered extensions to IMAP4rev1 1198 are also valid extensions to IMAP4rev2. 1200 Example: C: abcd CAPABILITY 1201 S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI 1202 LOGINDISABLED 1203 S: abcd OK CAPABILITY completed 1204 C: efgh STARTTLS 1205 S: efgh OK STARTLS completed 1206 1207 C: ijkl CAPABILITY 1208 S: * CAPABILITY IMAP4rev2 AUTH=GSSAPI AUTH=PLAIN 1209 S: ijkl OK CAPABILITY completed 1211 6.1.2. NOOP Command 1213 Arguments: none 1215 Responses: no specific responses for this command (but see below) 1217 Result: OK - noop completed 1218 BAD - command unknown or arguments invalid 1220 The NOOP command always succeeds. It does nothing. 1222 Since any command can return a status update as untagged data, the 1223 NOOP command can be used as a periodic poll for new messages or 1224 message status updates during a period of inactivity (the IDLE 1225 command Section 6.3.13 should be used instead of NOOP if real-time 1226 updates to mailbox state are desirable). The NOOP command can also 1227 be used to reset any inactivity autologout timer on the server. 1229 Example: C: a002 NOOP 1230 S: a002 OK NOOP completed 1231 . . . 1232 C: a047 NOOP 1233 S: * 22 EXPUNGE 1234 S: * 23 EXISTS 1235 S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted)) 1236 S: a047 OK NOOP completed 1238 6.1.3. LOGOUT Command 1240 Arguments: none 1242 Responses: REQUIRED untagged response: BYE 1244 Result: OK - logout completed 1245 BAD - command unknown or arguments invalid 1247 The LOGOUT command informs the server that the client is done with 1248 the connection. The server MUST send a BYE untagged response before 1249 the (tagged) OK response, and then close the network connection. 1251 Example: C: A023 LOGOUT 1252 S: * BYE IMAP4rev2 Server logging out 1253 S: A023 OK LOGOUT completed 1254 (Server and client then close the connection) 1256 6.2. Client Commands - Not Authenticated State 1258 In the not authenticated state, the AUTHENTICATE or LOGIN command 1259 establishes authentication and enters the authenticated state. The 1260 AUTHENTICATE command provides a general mechanism for a variety of 1261 authentication techniques, privacy protection, and integrity 1262 checking; whereas the LOGIN command uses a traditional user name and 1263 plaintext password pair and has no means of establishing privacy 1264 protection or integrity checking. 1266 The STARTTLS command is an alternative form of establishing session 1267 privacy protection and integrity checking, but does not by itself 1268 establish authentication or enter the authenticated state. 1270 Server implementations MAY allow access to certain mailboxes without 1271 establishing authentication. This can be done by means of the 1272 ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older 1273 convention is a LOGIN command using the userid "anonymous"; in this 1274 case, a password is required although the server may choose to accept 1275 any password. The restrictions placed on anonymous users are 1276 implementation-dependent. 1278 Once authenticated (including as anonymous), it is not possible to 1279 re-enter not authenticated state. 1281 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1282 the following commands are valid in the not authenticated state: 1283 STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations 1284 (Section 11) for important information about these commands. 1286 6.2.1. STARTTLS Command 1288 Arguments: none 1290 Responses: no specific response for this command 1292 Result: OK - starttls completed, begin TLS negotiation 1293 BAD - STARTTLS received after a successful TLS 1294 negotiation or arguments invalid 1296 A TLS [TLS-1.3] negotiation begins immediately after the CRLF at the 1297 end of the tagged OK response from the server. Once a client issues 1298 a STARTTLS command, it MUST NOT issue further commands until a server 1299 response is seen and the TLS negotiation is complete. 1301 The server remains in the non-authenticated state, even if client 1302 credentials are supplied during the TLS negotiation. This does not 1303 preclude an authentication mechanism such as EXTERNAL (defined in 1304 [SASL]) from using client identity determined by the TLS negotiation. 1306 Once TLS has been started, the client MUST discard cached information 1307 about server capabilities and SHOULD re-issue the CAPABILITY command. 1308 This is necessary to protect against man-in- the-middle attacks which 1309 alter the capabilities list prior to STARTTLS. The server MAY 1310 advertise different capabilities, and in particular SHOULD NOT 1311 advertise the STARTTLS capability, after a successful STARTTLS 1312 command. 1314 Example: C: a001 CAPABILITY 1315 S: * CAPABILITY IMAP4rev2 STARTTLS LOGINDISABLED 1316 S: a001 OK CAPABILITY completed 1317 C: a002 STARTTLS 1318 S: a002 OK Begin TLS negotiation now 1319 1320 C: a003 CAPABILITY 1321 S: * CAPABILITY IMAP4rev2 AUTH=PLAIN 1322 S: a003 OK CAPABILITY completed 1323 C: a004 LOGIN joe password 1324 S: a004 OK LOGIN completed 1326 6.2.2. AUTHENTICATE Command 1328 Arguments: SASL authentication mechanism name 1329 OPTIONAL initial response 1331 Responses: continuation data can be requested 1333 Result: OK - authenticate completed, now in authenticated state 1334 NO - authenticate failure: unsupported authentication 1335 mechanism, credentials rejected 1336 BAD - command unknown or arguments invalid, 1337 authentication exchange cancelled 1339 The AUTHENTICATE command indicates a [SASL] authentication mechanism 1340 to the server. If the server supports the requested authentication 1341 mechanism, it performs an authentication protocol exchange to 1342 authenticate and identify the client. It MAY also negotiate an 1343 OPTIONAL security layer for subsequent protocol interactions. If the 1344 requested authentication mechanism is not supported, the server 1345 SHOULD reject the AUTHENTICATE command by sending a tagged NO 1346 response. 1348 The AUTHENTICATE command supports the optional "initial response" 1349 feature defined in Section 5.1 of [SASL]. The client doesn't need to 1350 use it. If a SASL mechanism supports "initial response", but it is 1351 not specified by the client, the server handles this as specified in 1352 Section 3 of [SASL]. 1354 The service name specified by this protocol's profile of [SASL] is 1355 "imap". 1357 The authentication protocol exchange consists of a series of server 1358 challenges and client responses that are specific to the 1359 authentication mechanism. A server challenge consists of a command 1360 continuation request response with the "+" token followed by a BASE64 1361 encoded (see Section 4 of [RFC4648]) string. The client response 1362 consists of a single line consisting of a BASE64 encoded string. If 1363 the client wishes to cancel an authentication exchange, it issues a 1364 line consisting of a single "*". If the server receives such a 1365 response, or if it receives an invalid BASE64 string (e.g. 1366 characters outside the BASE64 alphabet, or non-terminal "="), it MUST 1367 reject the AUTHENTICATE command by sending a tagged BAD response. 1369 As with any other client response, this initial response MUST be 1370 encoded as BASE64. It also MUST be transmitted outside of a quoted 1371 string or literal. To send a zero-length initial response, the 1372 client MUST send a single pad character ("="). This indicates that 1373 the response is present, but is a zero-length string. 1375 When decoding the BASE64 data in the initial response, decoding 1376 errors MUST be treated as in any normal SASL client response, i.e. 1377 with a tagged BAD response. In particular, the server should check 1378 for any characters not explicitly allowed by the BASE64 alphabet, as 1379 well as any sequence of BASE64 characters that contains the pad 1380 character ('=') anywhere other than the end of the string (e.g., 1381 "=AAA" and "AAA=BBB" are not allowed). 1383 If the client uses an initial response with a SASL mechanism that 1384 does not support an initial response, the server MUST reject the 1385 command with a tagged BAD response. 1387 If a security layer is negotiated through the [SASL] authentication 1388 exchange, it takes effect immediately following the CRLF that 1389 concludes the authentication exchange for the client, and the CRLF of 1390 the tagged OK response for the server. 1392 While client and server implementations MUST implement the 1393 AUTHENTICATE command itself, it is not required to implement any 1394 authentication mechanisms other than the PLAIN mechanism described in 1395 [PLAIN]. Also, an authentication mechanism is not required to 1396 support any security layers. 1398 Note: a server implementation MUST implement a configuration in 1399 which it does NOT permit any plaintext password mechanisms, unless 1400 either the STARTTLS command has been negotiated or some other 1401 mechanism that protects the session from password snooping has 1402 been provided. Server sites SHOULD NOT use any configuration 1403 which permits a plaintext password mechanism without such a 1404 protection mechanism against password snooping. Client and server 1405 implementations SHOULD implement additional [SASL] mechanisms that 1406 do not use plaintext passwords, such the GSSAPI mechanism 1407 described in [SASL] and/or the SCRAM-SHA-256/SCRAM-SHA-256-PLUS 1408 [SCRAM-SHA-256] mechanisms. 1410 Servers and clients can support multiple authentication mechanisms. 1411 The server SHOULD list its supported authentication mechanisms in the 1412 response to the CAPABILITY command so that the client knows which 1413 authentication mechanisms to use. 1415 A server MAY include a CAPABILITY response code in the tagged OK 1416 response of a successful AUTHENTICATE command in order to send 1417 capabilities automatically. It is unnecessary for a client to send a 1418 separate CAPABILITY command if it recognizes these automatic 1419 capabilities. This should only be done if a security layer was not 1420 negotiated by the AUTHENTICATE command, because the tagged OK 1421 response as part of an AUTHENTICATE command is not protected by 1422 encryption/integrity checking. [SASL] requires the client to re- 1423 issue a CAPABILITY command in this case. The server MAY advertise 1424 different capabilities after a successful AUTHENTICATE command. 1426 If an AUTHENTICATE command fails with a NO response, the client MAY 1427 try another authentication mechanism by issuing another AUTHENTICATE 1428 command. It MAY also attempt to authenticate by using the LOGIN 1429 command (see Section 6.2.3 for more detail). In other words, the 1430 client MAY request authentication types in decreasing order of 1431 preference, with the LOGIN command as a last resort. 1433 The authorization identity passed from the client to the server 1434 during the authentication exchange is interpreted by the server as 1435 the user name whose privileges the client is requesting. 1437 Example: S: * OK IMAP4rev2 Server 1438 C: A001 AUTHENTICATE GSSAPI 1439 S: + 1440 C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw 1441 MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0 1442 b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW 1443 Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA 1444 cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX 1445 AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y 1446 C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb 1447 I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi 1448 vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL 1449 pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n 1450 FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE 1451 NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx 1452 O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB 1453 vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg== 1454 S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC 1455 AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0 1456 uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg== 1457 C: 1458 S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe 1459 ceP2CWY0SR0fAQAgAAQEBAQ= 1460 C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP 1461 wkhbfa2QteAQAgAG1yYwE= 1462 S: A001 OK GSSAPI authentication successful 1464 Note: The line breaks within server challenges and client responses 1465 are for editorial clarity and are not in real authenticators. 1467 6.2.3. LOGIN Command 1469 Arguments: user name 1470 password 1472 Responses: no specific responses for this command 1474 Result: OK - login completed, now in authenticated state 1475 NO - login failure: user name or password rejected 1476 BAD - command unknown or arguments invalid 1478 The LOGIN command identifies the client to the server and carries the 1479 plaintext password authenticating this user. 1481 A server MAY include a CAPABILITY response code in the tagged OK 1482 response to a successful LOGIN command in order to send capabilities 1483 automatically. It is unnecessary for a client to send a separate 1484 CAPABILITY command if it recognizes these automatic capabilities. 1486 Example: C: a001 LOGIN SMITH SESAME 1487 S: a001 OK LOGIN completed 1489 Note: Use of the LOGIN command over an insecure network (such as the 1490 Internet) is a security risk, because anyone monitoring network 1491 traffic can obtain plaintext passwords. The LOGIN command SHOULD NOT 1492 be used except as a last resort, and it is recommended that client 1493 implementations have a means to disable any automatic use of the 1494 LOGIN command. 1496 Unless either the client is accessing IMAP service on IMAPS port 1497 [RFC8314], the STARTTLS command has been negotiated or some other 1498 mechanism that protects the session from password snooping has been 1499 provided, a server implementation MUST implement a configuration in 1500 which it advertises the LOGINDISABLED capability and does NOT permit 1501 the LOGIN command. Server sites SHOULD NOT use any configuration 1502 which permits the LOGIN command without such a protection mechanism 1503 against password snooping. A client implementation MUST NOT send a 1504 LOGIN command if the LOGINDISABLED capability is advertised. 1506 6.3. Client Commands - Authenticated State 1508 In the authenticated state, commands that manipulate mailboxes as 1509 atomic entities are permitted. Of these commands, the SELECT and 1510 EXAMINE commands will select a mailbox for access and enter the 1511 selected state. 1513 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1514 the following commands are valid in the authenticated state: ENABLE, 1515 SELECT, EXAMINE, NAMESPACE, CREATE, DELETE, RENAME, SUBSCRIBE, 1516 UNSUBSCRIBE, LIST, STATUS, APPEND and IDLE. 1518 6.3.1. ENABLE Command 1520 Arguments: capability names 1522 Responses: no specific responses for this command 1524 Result: OK - Relevant capabilities enabled 1525 BAD - No arguments, or syntax error in an argument 1527 Several IMAP extensions allow the server to return unsolicited 1528 responses specific to these extensions in certain circumstances. 1529 However, servers cannot send those unsolicited responses (with the 1530 exception of response codes (see Section 7.1) included in tagged or 1531 untagged OK/NO/BAD responses, which can always be sent) until they 1532 know that the clients support such extensions and thus won't choke on 1533 the extension response data. 1535 The ENABLE command provides an explicit indication from the client 1536 that it supports particular extensions. It is designed such that the 1537 client can send a simple constant string with the extensions it 1538 supports, and the server will enable the shared subset that both 1539 support. 1541 The ENABLE command takes a list of capability names, and requests the 1542 server to enable the named extensions. Once enabled using ENABLE, 1543 each extension remains active until the IMAP connection is closed. 1544 For each argument, the server does the following: 1546 o If the argument is not an extension known to the server, the 1547 server MUST ignore the argument. 1549 o If the argument is an extension known to the server, and it is not 1550 specifically permitted to be enabled using ENABLE, the server MUST 1551 ignore the argument. (Note that knowing about an extension 1552 doesn't necessarily imply supporting that extension.) 1554 o If the argument is an extension that is supported by the server 1555 and that needs to be enabled, the server MUST enable the extension 1556 for the duration of the connection. Note that once an extension 1557 is enabled, there is no way to disable it. 1559 If the ENABLE command is successful, the server MUST send an untagged 1560 ENABLED response Section 7.2.1, which includes all enabled extensions 1561 as specified above. The ENABLED response is sent even if no 1562 extensions were enabled. 1564 Clients SHOULD only include extensions that need to be enabled by the 1565 server. For example, a client can enable IMAP4rev2 specific 1566 behaviour when both IMAP4rev1 and IMAP4rev2 are advertised in the 1567 CAPABILITY response. Future RFCs may add to this list. 1569 The ENABLE command is only valid in the authenticated state, before 1570 any mailbox is selected. Clients MUST NOT issue ENABLE once they 1571 SELECT/EXAMINE a mailbox; however, server implementations don't have 1572 to check that no mailbox is selected or was previously selected 1573 during the duration of a connection. 1575 The ENABLE command can be issued multiple times in a session. It is 1576 additive; i.e., "ENABLE a b", followed by "ENABLE c" is the same as a 1577 single command "ENABLE a b c". When multiple ENABLE commands are 1578 issued, each corresponding ENABLED response SHOULD only contain 1579 extensions enabled by the corresponding ENABLE command, i.e. for the 1580 above example, the ENABLED response to "ENABLE c" should not contain 1581 "a" or "b". 1583 There are no limitations on pipelining ENABLE. For example, it is 1584 possible to send ENABLE and then immediately SELECT, or a LOGIN 1585 immediately followed by ENABLE. 1587 The server MUST NOT change the CAPABILITY list as a result of 1588 executing ENABLE; i.e., a CAPABILITY command issued right after an 1589 ENABLE command MUST list the same capabilities as a CAPABILITY 1590 command issued before the ENABLE command. This is demonstrated in 1591 the following example. Note that below "X-GOOD-IDEA" is a fictitious 1592 extension capability that can be ENABLEd. 1594 C: t1 CAPABILITY 1595 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1596 S: t1 OK foo 1597 C: t2 ENABLE CONDSTORE X-GOOD-IDEA 1598 S: * ENABLED X-GOOD-IDEA 1599 S: t2 OK foo 1600 C: t3 CAPABILITY 1601 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1602 S: t3 OK foo again 1604 In the following example, the client enables CONDSTORE: 1606 C: a1 ENABLE CONDSTORE 1607 S: * ENABLED CONDSTORE 1608 S: a1 OK Conditional Store enabled 1610 6.3.1.1. Note to Designers of Extensions That May Use the ENABLE 1611 Command 1613 Designers of IMAP extensions are discouraged from creating extensions 1614 that require ENABLE unless there is no good alternative design. 1615 Specifically, extensions that cause potentially incompatible behavior 1616 changes to deployed server responses (and thus benefit from ENABLE) 1617 have a higher complexity cost than extensions that do not. 1619 6.3.2. SELECT Command 1621 Arguments: mailbox name 1623 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1624 REQUIRED OK untagged responses: PERMANENTFLAGS, 1625 UIDNEXT, UIDVALIDITY 1626 REQUIRED untagged response: LIST 1628 Result: OK - select completed, now in selected state 1629 NO - select failure, now in authenticated state: no 1630 such mailbox, can't access mailbox 1631 BAD - command unknown or arguments invalid 1633 The SELECT command selects a mailbox so that messages in the mailbox 1634 can be accessed. Before returning an OK to the client, the server 1635 MUST send the following untagged data to the client. (The order of 1636 individual responses is not important.) Note that earlier versions 1637 of this protocol (e.g. IMAP2bis) only required the FLAGS and EXISTS 1638 untagged data; consequently, client implementations SHOULD implement 1639 default behavior for missing data as discussed with the individual 1640 item. 1642 FLAGS Defined flags in the mailbox. See the description of the 1643 FLAGS response in Section 7.2.7 for more detail. 1645 EXISTS The number of messages in the mailbox. See the 1646 description of the EXISTS response in Section 7.3.1 for more 1647 detail. 1649 LIST The server MUST return a LIST response with the mailbox name. 1650 If the server allows de-normalized UTF-8 mailbox names (see 1651 Section 5.1) and the supplied mailbox name differs from the 1652 normalized version, the server MUST return LIST with the OLDNAME 1653 extended data item. See Section 6.3.9.7 for more details. 1655 OK [PERMANENTFLAGS ()] A list of message flags that 1656 the client can change permanently. If this is missing, the client 1657 should assume that all flags can be changed permanently. 1659 OK [UIDNEXT ] The next unique identifier value. Refer to 1660 Section 2.3.1.1 for more information. 1662 OK [UIDVALIDITY ] The unique identifier validity value. Refer to 1663 Section 2.3.1.1 for more information. 1665 Only one mailbox can be selected at a time in a connection; 1666 simultaneous access to multiple mailboxes requires multiple 1667 connections. The SELECT command automatically deselects any 1668 currently selected mailbox before attempting the new selection. 1669 Consequently, if a mailbox is selected and a SELECT command that 1670 fails is attempted, no mailbox is selected. When deselecting a 1671 selected mailbox, the server MUST return an untagged OK response with 1672 the "[CLOSED]" response code when the currently selected mailbox is 1673 closed (see Paragraph 10). 1675 If the client is permitted to modify the mailbox, the server SHOULD 1676 prefix the text of the tagged OK response with the "[READ-WRITE]" 1677 response code. 1679 If the client is not permitted to modify the mailbox but is permitted 1680 read access, the mailbox is selected as read-only, and the server 1681 MUST prefix the text of the tagged OK response to SELECT with the 1682 "[READ-ONLY]" response code. Read-only access through SELECT differs 1683 from the EXAMINE command in that certain read-only mailboxes MAY 1684 permit the change of permanent state on a per-user (as opposed to 1685 global) basis. Netnews messages marked in a server-based .newsrc 1686 file are an example of such per-user permanent state that can be 1687 modified with read-only mailboxes. 1689 Example: C: A142 SELECT INBOX 1690 S: * 172 EXISTS 1691 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1692 S: * OK [UIDNEXT 4392] Predicted next UID 1693 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1694 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1695 S: * LIST () "/" INBOX 1696 S: A142 OK [READ-WRITE] SELECT completed 1698 Example: C: A142 SELECT INBOX 1699 S: * 172 EXISTS 1700 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1701 S: * OK [UIDNEXT 4392] Predicted next UID 1702 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1703 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1704 S: A142 OK [READ-WRITE] SELECT completed 1705 [...some time later...] 1706 C: A143 SELECT Drafts 1707 S: * OK [CLOSED] Previous mailbox is now closed 1708 S: * 5 EXISTS 1709 S: * OK [UIDVALIDITY 9877410381] UIDs valid 1710 S: * OK [UIDNEXT 102] Predicted next UID 1711 S: * LIST () "/" Drafts 1712 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1713 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Answered 1714 \Flagged \Draft \*)] System flags and keywords allowed 1715 S: A143 OK [READ-WRITE] SELECT completed 1717 Note that IMAP4rev1 compliant servers can also send the untagged 1718 RECENT response which was deprecated in IMAP4rev2. E.g. "* 0 1719 RECENT". Pure IMAP4rev2 clients are advised to ignore the untagged 1720 RECENT response. 1722 6.3.3. EXAMINE Command 1724 Arguments: mailbox name 1726 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1727 REQUIRED OK untagged responses: PERMANENTFLAGS, 1728 UIDNEXT, UIDVALIDITY 1729 REQUIRED untagged response: LIST 1731 Result: OK - examine completed, now in selected state 1732 NO - examine failure, now in authenticated state: no 1733 such mailbox, can't access mailbox BAD - command unknown 1734 or arguments invalid 1736 The EXAMINE command is identical to SELECT and returns the same 1737 output; however, the selected mailbox is identified as read-only. No 1738 changes to the permanent state of the mailbox, including per-user 1739 state, are permitted. 1741 The text of the tagged OK response to the EXAMINE command MUST begin 1742 with the "[READ-ONLY]" response code. 1744 Example: C: A932 EXAMINE blurdybloop 1745 S: * 17 EXISTS 1746 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1747 S: * OK [UIDNEXT 4392] Predicted next UID 1748 S: * LIST () "/" blurdybloop 1749 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1750 S: * OK [PERMANENTFLAGS ()] No permanent flags permitted 1751 S: A932 OK [READ-ONLY] EXAMINE completed 1753 6.3.4. CREATE Command 1755 Arguments: mailbox name 1757 Responses: OPTIONAL untagged response: LIST 1759 Result: OK - create completed 1760 NO - create failure: can't create mailbox with that name 1761 BAD - command unknown or arguments invalid 1763 The CREATE command creates a mailbox with the given name. An OK 1764 response is returned only if a new mailbox with that name has been 1765 created. It is an error to attempt to create INBOX or a mailbox with 1766 a name that refers to an extant mailbox. Any error in creation will 1767 return a tagged NO response. If a client attempts to create a UTF-8 1768 mailbox name that is not a valid Net-Unicode name, the server MUST 1769 reject the creation or convert the name to Net-Unicode prior to 1770 creating the mailbox. If the server decides to convert (normalize) 1771 the name, it SHOULD return an untagged LIST with OLDNAME extended 1772 data item, with the OLDNAME value being the supplied mailbox name and 1773 the name parameter being the normalized mailbox name. (See 1774 Section 6.3.9.7 for more details.) 1775 Mailboxes created in one IMAP session MAY be announced to other IMAP 1776 sessions using unsolicited LIST response. If the server 1777 automatically subscribes a mailbox when it is created, then the 1778 unsolicited LIST response for each affected subscribed mailbox name 1779 MUST include the \Subscribed attribute. 1781 If the mailbox name is suffixed with the server's hierarchy separator 1782 character (as returned from the server by a LIST command), this is a 1783 declaration that the client intends to create mailbox names under 1784 this name in the hierarchy. Server implementations that do not 1785 require this declaration MUST ignore the declaration. In any case, 1786 the name created is without the trailing hierarchy delimiter. 1788 If the server's hierarchy separator character appears elsewhere in 1789 the name, the server SHOULD create any superior hierarchical names 1790 that are needed for the CREATE command to be successfully completed. 1791 In other words, an attempt to create "foo/bar/zap" on a server in 1792 which "/" is the hierarchy separator character SHOULD create foo/ and 1793 foo/bar/ if they do not already exist. 1795 If a new mailbox is created with the same name as a mailbox which was 1796 deleted, its unique identifiers MUST be greater than any unique 1797 identifiers used in the previous incarnation of the mailbox unless 1798 the new incarnation has a different unique identifier validity value. 1799 See the description of the UID command in Section 6.4.9 for more 1800 detail. 1802 Example: C: A003 CREATE owatagusiam/ 1803 S: A003 OK CREATE completed 1804 C: A004 CREATE owatagusiam/blurdybloop 1805 S: A004 OK CREATE completed 1806 C: A005 CREATE NonNormalized 1807 S: * LIST () "/" "Normalized" ("OLDNAME" ("NonNormalized")) 1808 S: A005 OK CREATE completed 1810 (in the last example imagine that "NonNormalized" is 1811 a non NFC normalized Unicode mailbox name and that 1812 "Normalized" is its NFC normalized version.) 1814 Note: The interpretation of this example depends on whether "/" 1815 was returned as the hierarchy separator from LIST. If "/" is the 1816 hierarchy separator, a new level of hierarchy named "owatagusiam" 1817 with a member called "blurdybloop" is created. Otherwise, two 1818 mailboxes at the same hierarchy level are created. 1820 6.3.5. DELETE Command 1822 Arguments: mailbox name 1824 Responses: OPTIONAL untagged response: LIST 1826 Result: OK - delete completed 1827 NO - delete failure: can't delete mailbox with that name 1828 BAD - command unknown or arguments invalid 1830 The DELETE command permanently removes the mailbox with the given 1831 name. A tagged OK response is returned only if the mailbox has been 1832 deleted. It is an error to attempt to delete INBOX or a mailbox name 1833 that does not exist. 1835 The DELETE command MUST NOT remove inferior hierarchical names. For 1836 example, if a mailbox "foo" has an inferior "foo.bar" (assuming "." 1837 is the hierarchy delimiter character), removing "foo" MUST NOT remove 1838 "foo.bar". It is an error to attempt to delete a name that has 1839 inferior hierarchical names and also has the \Noselect mailbox name 1840 attribute (see the description of the LIST response (Section 7.2.3) 1841 for more details). 1843 It is permitted to delete a name that has inferior hierarchical names 1844 and does not have the \Noselect mailbox name attribute. If the 1845 server implementation does not permit deleting the name while 1846 inferior hierarchical names exists then it SHOULD disallow the DELETE 1847 command by returning a tagged NO response. The NO response SHOULD 1848 include the HASCHILDREN response code. Alternatively the server MAY 1849 allow the DELETE command, but sets the \Noselect mailbox name 1850 attribute for that name. 1852 If the server returns OK response, all messages in that mailbox are 1853 removed by the DELETE command. 1855 The value of the highest-used unique identifier of the deleted 1856 mailbox MUST be preserved so that a new mailbox created with the same 1857 name will not reuse the identifiers of the former incarnation, unless 1858 the new incarnation has a different unique identifier validity value. 1859 See the description of the UID command in Section 6.4.9 for more 1860 detail. 1862 If the server decides to convert (normalize) the mailbox name, it 1863 SHOULD return an untagged LIST with the "\NonExistent" attribute and 1864 OLDNAME extended data item, with the OLDNAME value being the supplied 1865 mailbox name and the name parameter being the normalized mailbox 1866 name. (See Section 6.3.9.7 for more details.) 1867 Mailboxes deleted in one IMAP session MAY be announced to other IMAP 1868 sessions using unsolicited LIST response, containing the 1869 "\NonExistent" attribute. 1871 Examples: C: A682 LIST "" * 1872 S: * LIST () "/" blurdybloop 1873 S: * LIST (\Noselect) "/" foo 1874 S: * LIST () "/" foo/bar 1875 S: A682 OK LIST completed 1876 C: A683 DELETE blurdybloop 1877 S: A683 OK DELETE completed 1878 C: A684 DELETE foo 1879 S: A684 NO Name "foo" has inferior hierarchical names 1880 C: A685 DELETE foo/bar 1881 S: A685 OK DELETE Completed 1882 C: A686 LIST "" * 1883 S: * LIST (\Noselect) "/" foo 1884 S: A686 OK LIST completed 1885 C: A687 DELETE foo 1886 S: A687 OK DELETE Completed 1887 C: A82 LIST "" * 1888 S: * LIST () "." blurdybloop 1889 S: * LIST () "." foo 1890 S: * LIST () "." foo.bar 1891 S: A82 OK LIST completed 1892 C: A83 DELETE blurdybloop 1893 S: A83 OK DELETE completed 1894 C: A84 DELETE foo 1895 S: A84 OK DELETE Completed 1896 C: A85 LIST "" * 1897 S: * LIST () "." foo.bar 1898 S: A85 OK LIST completed 1899 C: A86 LIST "" % 1900 S: * LIST (\Noselect) "." foo 1901 S: A86 OK LIST completed 1903 6.3.6. RENAME Command 1905 Arguments: existing mailbox name 1906 new mailbox name 1908 Responses: OPTIONAL untagged response: LIST 1910 Result: OK - rename completed 1911 NO - rename failure: can't rename mailbox with that name, 1912 can't rename to mailbox with that name 1913 BAD - command unknown or arguments invalid 1915 The RENAME command changes the name of a mailbox. A tagged OK 1916 response is returned only if the mailbox has been renamed. It is an 1917 error to attempt to rename from a mailbox name that does not exist or 1918 to a mailbox name that already exists. Any error in renaming will 1919 return a tagged NO response. 1921 If the name has inferior hierarchical names, then the inferior 1922 hierarchical names MUST also be renamed. For example, a rename of 1923 "foo" to "zap" will rename "foo/bar" (assuming "/" is the hierarchy 1924 delimiter character) to "zap/bar". 1926 If the server's hierarchy separator character appears in the name, 1927 the server SHOULD create any superior hierarchical names that are 1928 needed for the RENAME command to complete successfully. In other 1929 words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a 1930 server in which "/" is the hierarchy separator character in the 1931 corresponding namespace SHOULD create baz/ and baz/rag/ if they do 1932 not already exist. 1934 The value of the highest-used unique identifier of the old mailbox 1935 name MUST be preserved so that a new mailbox created with the same 1936 name will not reuse the identifiers of the former incarnation, unless 1937 the new incarnation has a different unique identifier validity value. 1938 See the description of the UID command in Section 6.4.9 for more 1939 detail. 1941 Renaming INBOX is permitted (i.e. it doesn't result in a tagged BAD 1942 response), and has special behavior. (Note that some servers 1943 disallow renaming INBOX by returning a tagged NO response, so clients 1944 need to be able to handle such RENAME failing). It moves all 1945 messages in INBOX to a new mailbox with the given name, leaving INBOX 1946 empty. If the server implementation supports inferior hierarchical 1947 names of INBOX, these are unaffected by a rename of INBOX. 1949 If the server allows creation of mailboxes with names that are not 1950 valid Net-Unicode names, the server normalizes both the existing 1951 mailbox name parameter and the new mailbox name parameter. If the 1952 normalized version of any of these 2 parameters differs from the 1953 corresponding supplied version, the server SHOULD return an untagged 1954 LIST response with OLDNAME extended data item, with the OLDNAME value 1955 being the supplied existing mailbox name and the name parameter being 1956 the normalized new mailbox name (see Section 6.3.9.7). This would 1957 allow the client to correlate supplied name with the normalized name. 1959 Mailboxes renamed in one IMAP session MAY be announced to other IMAP 1960 sessions using unsolicited LIST response with OLDNAME extended data 1961 item. 1963 In both of the above cases: if the server automatically subscribes a 1964 mailbox when it is renamed, then the unsolicited LIST response for 1965 each affected subscribed mailbox name MUST include the \Subscribed 1966 attribute. No unsolicited LIST responses need to be sent for 1967 children mailboxes, if any. When INBOX is successfully renamed, a 1968 new INBOX is assumed to be created. No unsolicited LIST responses 1969 need to be sent for INBOX in this case. 1971 Examples: C: A682 LIST "" * 1972 S: * LIST () "/" blurdybloop 1973 S: * LIST (\Noselect) "/" foo 1974 S: * LIST () "/" foo/bar 1975 S: A682 OK LIST completed 1976 C: A683 RENAME blurdybloop sarasoop 1977 S: A683 OK RENAME completed 1978 C: A684 RENAME foo zowie 1979 S: A684 OK RENAME Completed 1980 C: A685 LIST "" * 1981 S: * LIST () "/" sarasoop 1982 S: * LIST (\Noselect) "/" zowie 1983 S: * LIST () "/" zowie/bar 1984 S: A685 OK LIST completed 1986 C: Z432 LIST "" * 1987 S: * LIST () "." INBOX 1988 S: * LIST () "." INBOX.bar 1989 S: Z432 OK LIST completed 1990 C: Z433 RENAME INBOX old-mail 1991 S: Z433 OK RENAME completed 1992 C: Z434 LIST "" * 1993 S: * LIST () "." INBOX 1994 S: * LIST () "." INBOX.bar 1995 S: * LIST () "." old-mail 1996 S: Z434 OK LIST completed 1998 Note that renaming a mailbox doesn't update subscription information 1999 on the original name. To keep subscription information in sync, the 2000 following sequence of commands can be used: 2002 C: 1001 RENAME X Y 2003 C: 1002 SUBSCRIBE Y 2004 C: 1003 UNSUBSCRIBE X 2006 Note that the above sequence of commands doesn't account for updating 2007 subscription for any children mailboxes of mailbox X. 2009 6.3.7. SUBSCRIBE Command 2011 Arguments: mailbox 2013 Responses: no specific responses for this command 2015 Result: OK - subscribe completed 2016 NO - subscribe failure: can't subscribe to that name 2017 BAD - command unknown or arguments invalid 2019 The SUBSCRIBE command adds the specified mailbox name to the server's 2020 set of "active" or "subscribed" mailboxes as returned by the LIST 2021 (SUBSCRIBED) command. This command returns a tagged OK response if 2022 the subscription is successful or if the mailbox is already 2023 subscribed. 2025 A server MAY validate the mailbox argument to SUBSCRIBE to verify 2026 that it exists. However, it SHOULD NOT unilaterally remove an 2027 existing mailbox name from the subscription list even if a mailbox by 2028 that name no longer exists. 2030 Note: This requirement is because a server site can choose to 2031 routinely remove a mailbox with a well-known name (e.g., "system- 2032 alerts") after its contents expire, with the intention of 2033 recreating it when new contents are appropriate. 2035 Example: C: A002 SUBSCRIBE #news.comp.mail.mime 2036 S: A002 OK SUBSCRIBE completed 2038 6.3.8. UNSUBSCRIBE Command 2040 Arguments: mailbox name 2042 Responses: no specific responses for this command 2044 Result: OK - unsubscribe completed 2045 NO - unsubscribe failure: can't unsubscribe that name 2046 BAD - command unknown or arguments invalid 2048 The UNSUBSCRIBE command removes the specified mailbox name from the 2049 server's set of "active" or "subscribed" mailboxes as returned by the 2050 LIST (SUBSCRIBED) command. This command returns a tagged OK response 2051 if the unsubscription is successful or if the mailbox is not 2052 subscribed. 2054 Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime 2055 S: A002 OK UNSUBSCRIBE completed 2057 6.3.9. LIST Command 2059 Arguments (basic): reference name 2060 mailbox name with possible wildcards 2062 Arguments (extended): selection options (OPTIONAL) 2063 reference name 2064 mailbox patterns 2065 return options (OPTIONAL) 2067 Responses: untagged responses: LIST 2069 Result: OK - list completed 2070 NO - list failure: can't list that reference or mailbox 2071 name 2072 BAD - command unknown or arguments invalid 2074 The LIST command returns a subset of mailbox names from the complete 2075 set of all mailbox names available to the client. Zero or more 2076 untagged LIST responses are returned, containing the name attributes, 2077 hierarchy delimiter, name, and possible extension information; see 2078 the description of the LIST response (Section 7.2.3) for more detail. 2080 The LIST command SHOULD return its data quickly, without undue delay. 2081 For example, it SHOULD NOT go to excess trouble to calculate the 2082 \Marked or \Unmarked status or perform other processing; if each name 2083 requires 1 second of processing, then a list of 1200 names would take 2084 20 minutes! 2086 The extended LIST command, originally introduced in [RFC5258], 2087 provides capabilities beyond that of the original IMAP LIST command. 2088 The extended syntax is being used if one or more of the following 2089 conditions is true: 2091 1. if the first word after the command name begins with a 2092 parenthesis ("LIST selection options"); 2094 2. if the second word after the command name begins with a 2095 parenthesis; 2097 3. if the LIST command has more than 2 parameters ("LIST return 2098 options") 2100 An empty ("" string) reference name argument indicates that the 2101 mailbox name is interpreted as by SELECT. The returned mailbox names 2102 MUST match the supplied mailbox name pattern(s). A non-empty 2103 reference name argument is the name of a mailbox or a level of 2104 mailbox hierarchy, and indicates the context in which the mailbox 2105 name is interpreted. Clients SHOULD use the empty reference 2106 argument. 2108 In the basic syntax only, an empty ("" string) mailbox name argument 2109 is a special request to return the hierarchy delimiter and the root 2110 name of the name given in the reference. The value returned as the 2111 root MAY be the empty string if the reference is non-rooted or is an 2112 empty string. In all cases, a hierarchy delimiter (or NIL if there 2113 is no hierarchy) is returned. This permits a client to get the 2114 hierarchy delimiter (or find out that the mailbox names are flat) 2115 even when no mailboxes by that name currently exist. 2117 In the extended syntax, any mailbox name arguments that are empty 2118 strings are ignored. There is no special meaning for empty mailbox 2119 names when the extended syntax is used. 2121 The reference and mailbox name arguments are interpreted into a 2122 canonical form that represents an unambiguous left-to-right 2123 hierarchy. The returned mailbox names will be in the interpreted 2124 form, that we call "canonical LIST pattern" later in this document. 2125 To define the term "canonical LIST pattern" formally: it refers to 2126 the canonical pattern constructed internally by the server from the 2127 reference and mailbox name arguments. 2129 Note: The interpretation of the reference argument is 2130 implementation-defined. It depends upon whether the server 2131 implementation has a concept of the "current working directory" 2132 and leading "break out characters", which override the current 2133 working directory. 2135 For example, on a server which exports a UNIX or NT filesystem, 2136 the reference argument contains the current working directory, and 2137 the mailbox name argument would contain the name as interpreted in 2138 the current working directory. 2140 If a server implementation has no concept of break out characters, 2141 the canonical form is normally the reference name appended with 2142 the mailbox name. Note that if the server implements the 2143 namespace convention (Section 5.1.2.1), "#" is a break out 2144 character and must be treated as such. 2146 If the reference argument is not a level of mailbox hierarchy 2147 (that is, it is a \NoInferiors name), and/or the reference 2148 argument does not end with the hierarchy delimiter, it is 2149 implementation-dependent how this is interpreted. For example, a 2150 reference of "foo/bar" and mailbox name of "rag/baz" could be 2151 interpreted as "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/ 2152 baz". A client SHOULD NOT use such a reference argument except at 2153 the explicit request of the user. A hierarchical browser MUST NOT 2154 make any assumptions about server interpretation of the reference 2155 unless the reference is a level of mailbox hierarchy AND ends with 2156 the hierarchy delimiter. 2158 Any part of the reference argument that is included in the 2159 interpreted form SHOULD prefix the interpreted form. It SHOULD also 2160 be in the same form as the reference name argument. This rule 2161 permits the client to determine if the returned mailbox name is in 2162 the context of the reference argument, or if something about the 2163 mailbox argument overrode the reference argument. Without this rule, 2164 the client would have to have knowledge of the server's naming 2165 semantics including what characters are "breakouts" that override a 2166 naming context. 2168 Here are some examples of how references 2169 and mailbox names might be interpreted on a UNIX-based 2170 server: 2172 Reference Mailbox Name Interpretation 2173 ------------ ------------ -------------- 2174 ~smith/Mail/ foo.* ~smith/Mail/foo.* 2175 archive/ % archive/% 2176 #news. comp.mail.* #news.comp.mail.* 2177 ~smith/Mail/ /usr/doc/foo /usr/doc/foo 2178 archive/ ~fred/Mail/* ~fred/Mail/* 2180 The first three examples demonstrate interpretations in 2181 the context of the reference argument. Note that 2182 "~smith/Mail" SHOULD NOT be transformed into something 2183 like "/u2/users/smith/Mail", or it would be impossible 2184 for the client to determine that the interpretation was 2185 in the context of the reference. 2187 The character "*" is a wildcard, and matches zero or more characters 2188 at this position. The character "%" is similar to "*", but it does 2189 not match a hierarchy delimiter. If the "%" wildcard is the last 2190 character of a mailbox name argument, matching levels of hierarchy 2191 are also returned. If these levels of hierarchy are not also 2192 selectable mailboxes, they are returned with the \Noselect mailbox 2193 name attribute (see the description of the LIST response 2194 (Section 7.2.3) for more details). 2196 Any syntactically valid pattern that is not accepted by a server for 2197 any reason MUST be silently ignored. I.e. it results in no LIST 2198 responses and the LIST command still returns tagged OK response. 2200 Selection options tell the server to limit the mailbox names that are 2201 selected by the LIST operation. If selection options are used, the 2202 mailboxes returned are those that match both the list of canonical 2203 LIST patterns and the selection options. Unless a particular 2204 selection option provides special rules, the selection options are 2205 cumulative: a mailbox that matches the mailbox patterns is selected 2206 only if it also matches all of the selection options. (An example of 2207 a selection option with special rules is the RECURSIVEMATCH option.) 2209 Return options control what information is returned for each matched 2210 mailbox. Return options MUST NOT cause the server to report 2211 information about additional mailbox names other than those that 2212 match the canonical LIST patterns and selection options. If no 2213 return options are specified, the client is only expecting 2214 information about mailbox attributes. The server MAY return other 2215 information about the matched mailboxes, and clients MUST be able to 2216 handle that situation. 2218 Initial selection options and return options are defined in the 2219 following subsections, and new ones will also be defined in 2220 extensions. Initial options defined in this document MUST be 2221 supported. Each non-initial option will be enabled by a capability 2222 string (one capability may enable multiple options), and a client 2223 MUST NOT send an option for which the server has not advertised 2224 support. A server MUST respond to options it does not recognize with 2225 a BAD response. The client SHOULD NOT specify any option more than 2226 once; however, if the client does this, the server MUST act as if it 2227 received the option only once. The order in which options are 2228 specified by the client is not significant. 2230 In general, each selection option except RECURSIVEMATCH will have a 2231 corresponding return option with the same name. The REMOTE selection 2232 option is an anomaly in this regard, and does not have a 2233 corresponding return option. That is because it expands, rather than 2234 restricts, the set of mailboxes that are returned. Future extensions 2235 to this specification should keep this parallelism in mind and define 2236 a pair of corresponding selection and return options. 2238 Server implementations are permitted to "hide" otherwise accessible 2239 mailboxes from the wildcard characters, by preventing certain 2240 characters or names from matching a wildcard in certain situations. 2241 For example, a UNIX-based server might restrict the interpretation of 2242 "*" so that an initial "/" character does not match. 2244 The special name INBOX is included in the output from LIST, if INBOX 2245 is supported by this server for this user and if the uppercase string 2246 "INBOX" matches the interpreted reference and mailbox name arguments 2247 with wildcards as described above. The criteria for omitting INBOX 2248 is whether SELECT INBOX will return failure; it is not relevant 2249 whether the user's real INBOX resides on this or some other server. 2251 6.3.9.1. LIST Selection Options 2253 The selection options defined in this specification are as follows: 2255 SUBSCRIBED - causes the LIST command to list subscribed names, 2256 rather than the existing mailboxes. This will often be a subset 2257 of the actual mailboxes. It's also possible for this list to 2258 contain the names of mailboxes that don't exist. In any case, the 2259 list MUST include exactly those mailbox names that match the 2260 canonical list pattern and are subscribed to. 2262 This option defines a mailbox attribute, "\Subscribed", that 2263 indicates that a mailbox name is subscribed to. The "\Subscribed" 2264 attribute MUST be supported and MUST be accurately computed when 2265 the SUBSCRIBED selection option is specified. 2267 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 2268 return option (see below). 2270 REMOTE - causes the LIST command to show remote mailboxes as well as 2271 local ones, as described in [RFC2193]. This option is intended to 2272 replace the RLIST command and, in conjunction with the SUBSCRIBED 2273 selection option, the RLSUB command. Servers that don't support 2274 remote mailboxes just ignore this option. 2276 This option defines a mailbox attribute, "\Remote", that indicates 2277 that a mailbox is a remote mailbox. The "\Remote" attribute MUST 2278 be accurately computed when the REMOTE option is specified. 2280 The REMOTE selection option has no interaction with other options. 2281 Its effect is to tell the server to apply the other options, if 2282 any, to remote mailboxes, in addition to local ones. In 2283 particular, it has no interaction with RECURSIVEMATCH (see below). 2284 A request for (REMOTE RECURSIVEMATCH) is invalid, because a 2285 request for (RECURSIVEMATCH) is also invalid. A request for 2286 (REMOTE RECURSIVEMATCH SUBSCRIBED) is asking for all subscribed 2287 mailboxes, both local and remote. 2289 RECURSIVEMATCH - this option forces the server to return information 2290 about parent mailboxes that don't match other selection options, 2291 but have some submailboxes that do. Information about children is 2292 returned in the CHILDINFO extended data item, as described in 2293 Section 6.3.9.6. 2295 Note 1: In order for a parent mailbox to be returned, it still has 2296 to match the canonical LIST pattern. 2298 Note 2: When returning the CHILDINFO extended data item, it 2299 doesn't matter whether or not the submailbox matches the canonical 2300 LIST pattern. See also example 9 in Section 6.3.9.8. 2302 The RECURSIVEMATCH option MUST NOT occur as the only selection 2303 option (or only with REMOTE), as it only makes sense when other 2304 selection options are also used. The server MUST return BAD 2305 tagged response in such case. 2307 Note that even if the RECURSIVEMATCH option is specified, the 2308 client MUST still be able to handle a case when a CHILDINFO 2309 extended data item is returned and there are no submailboxes that 2310 meet the selection criteria of the subsequent LIST command, as 2311 they can be deleted/renamed after the LIST response was sent, but 2312 before the client had a chance to access them. 2314 6.3.9.2. LIST Return Options 2316 The return options defined in this specification are as follows: 2318 SUBSCRIBED - causes the LIST command to return subscription state 2319 for all matching mailbox names. The "\Subscribed" attribute MUST 2320 be supported and MUST be accurately computed when the SUBSCRIBED 2321 return option is specified. Further, all mailbox flags MUST be 2322 accurately computed (this differs from the behavior of the 2323 obsolete LSUB command from IMAP4rev1). 2325 CHILDREN - requests mailbox child information as originally proposed 2326 in [RFC3348]. See Section 6.3.9.5, below, for details. 2328 STATUS - requests STATUS response for each matching mailbox. 2330 This option takes STATUS data items as parameters. For each 2331 selectable mailbox matching the list pattern and selection 2332 options, the server MUST return an untagged LIST response 2333 followed by an untagged STATUS response containing the 2334 information requested in the STATUS return option, except for 2335 some cases described below. 2337 If an attempted STATUS for a listed mailbox fails because the 2338 mailbox can't be selected (e.g., if the "l" ACL right [RFC4314] 2339 is granted to the mailbox and the "r" right is not granted, or 2340 due to a race condition between LIST and STATUS changing the 2341 mailbox to \NoSelect), the STATUS response MUST NOT be returned 2342 and the LIST response MUST include the \NoSelect attribute. 2343 This means the server may have to buffer the LIST reply until 2344 it has successfully looked up the necessary STATUS information. 2346 If the server runs into unexpected problems while trying to 2347 look up the STATUS information, it MAY drop the corresponding 2348 STATUS reply. In such a situation, the LIST command would 2349 still return a tagged OK reply. 2351 6.3.9.3. General Principles for Returning LIST Responses 2353 This section outlines several principles that can be used by server 2354 implementations of this document to decide whether a LIST response 2355 should be returned, as well as how many responses and what kind of 2356 information they may contain. 2358 1. At most one LIST response should be returned for each mailbox 2359 name that matches the canonical LIST pattern. Server 2360 implementors must not assume that clients will be able to 2361 assemble mailbox attributes and other information returned in 2362 multiple LIST responses. 2364 2. There are only two reasons for including a matching mailbox name 2365 in the responses to the LIST command (note that the server is 2366 allowed to return unsolicited responses at any time, and such 2367 responses are not governed by this rule): 2369 A. The mailbox name also satisfies the selection criteria. 2371 B. The mailbox name doesn't satisfy the selection criteria, but 2372 it has at least one descendant mailbox name that satisfies 2373 the selection criteria and that doesn't match the canonical 2374 LIST pattern. 2376 For more information on this case, see the CHILDINFO extended 2377 data item described in Section 6.3.9.6. Note that the 2378 CHILDINFO extended data item can only be returned when the 2379 RECURSIVEMATCH selection option is specified. 2381 3. Attributes returned in the same LIST response must be treated 2382 additively. For example, the following response 2384 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2386 means that the "Fruit/Peach" mailbox doesn't exist, but it is 2387 subscribed. 2389 6.3.9.4. Additional LIST-related Requirements on Clients 2391 All clients MUST treat a LIST attribute with a stronger meaning as 2392 implying any attribute that can be inferred from it. (See 2393 Section 7.2.3 for the list of currently defined attributes). For 2394 example, the client must treat the presence of the \NoInferiors 2395 attribute as if the \HasNoChildren attribute was also sent by the 2396 server. 2398 The following table summarizes inference rules. 2400 +--------------------+-------------------+ 2401 | returned attribute | implied attribute | 2402 +--------------------+-------------------+ 2403 | \NoInferiors | \HasNoChildren | 2404 | \NonExistent | \NoSelect | 2405 +--------------------+-------------------+ 2407 6.3.9.5. The CHILDREN Return Option 2409 The CHILDREN return option is simply an indication that the client 2410 wants information about whether or not mailboxes contain children 2411 mailboxes; a server MAY provide it even if the option is not 2412 specified. 2414 Many IMAP4 clients present to the user a hierarchical view of the 2415 mailboxes that a user has access to. Rather than initially 2416 presenting to the user the entire mailbox hierarchy, it is often 2417 preferable to show to the user a collapsed outline list of the 2418 mailbox hierarchy (particularly if there is a large number of 2419 mailboxes). The user can then expand the collapsed outline hierarchy 2420 as needed. It is common to include within the collapsed hierarchy a 2421 visual clue (such as a ''+'') to indicate that there are child 2422 mailboxes under a particular mailbox. When the visual clue is 2423 clicked, the hierarchy list is expanded to show the child mailboxes. 2424 The CHILDREN return option provides a mechanism for a client to 2425 efficiently determine whether a particular mailbox has children, 2426 without issuing a LIST "" * or a LIST "" % for each mailbox name. 2427 The CHILDREN return option defines two new attributes that MUST be 2428 returned within a LIST response: \HasChildren and \HasNoChildren. 2429 Although these attributes MAY be returned in response to any LIST 2430 command, the CHILDREN return option is provided to indicate that the 2431 client particularly wants this information. If the CHILDREN return 2432 option is present, the server MUST return these attributes even if 2433 their computation is expensive. 2435 \HasChildren 2436 The presence of this attribute indicates that the mailbox has 2437 child mailboxes. A server SHOULD NOT set this attribute if 2438 there are child mailboxes and the user does not have permission 2439 to access any of them. In this case, \HasNoChildren SHOULD be 2440 used. In many cases, however, a server may not be able to 2441 efficiently compute whether a user has access to any child 2442 mailbox. Note that even though the \HasChildren attribute for a 2443 mailbox must be correct at the time of processing of the 2444 mailbox, a client must be prepared to deal with a situation when 2445 a mailbox is marked with the \HasChildren attribute, but no 2446 child mailbox appears in the response to the LIST command. This 2447 might happen, for example, due to children mailboxes being 2448 deleted or made inaccessible to the user (using access control) 2449 by another client before the server is able to list them. 2451 \HasNoChildren 2453 The presence of this attribute indicates that the mailbox has NO 2454 child mailboxes that are accessible to the currently 2455 authenticated user. 2457 It is an error for the server to return both a \HasChildren and a 2458 \HasNoChildren attribute in the same LIST response. 2460 Note: the \HasNoChildren attribute should not be confused with the 2461 the \NoInferiors attribute, which indicates that no child mailboxes 2462 exist now and none can be created in the future. 2464 6.3.9.6. CHILDINFO Extended Data Item 2466 The CHILDINFO extended data item MUST NOT be returned unless the 2467 client has specified the RECURSIVEMATCH selection option. 2469 The CHILDINFO extended data item in a LIST response describes the 2470 selection criteria that has caused it to be returned and indicates 2471 that the mailbox has at least one descendant mailbox that matches the 2472 selection criteria. 2474 Note: Some servers allow for mailboxes to exist without requiring 2475 their parent to exist. For example, a mailbox "Customers/ABC" can 2476 exist while the mailbox "Customers" does not. As CHILDINFO extended 2477 data item is not allowed if the RECURSIVEMATCH selection option is 2478 not specified, such servers SHOULD use the "\NonExistent 2479 \HasChildren" attribute pair to signal to the client that there is a 2480 descendant mailbox that matches the selection criteria. See example 2481 11 in Section 6.3.9.8. 2483 The returned selection criteria allow the client to distinguish a 2484 solicited response from an unsolicited one, as well as to distinguish 2485 among solicited responses caused by multiple pipelined LIST commands 2486 that specify different criteria. 2488 Servers SHOULD only return a non-matching mailbox name along with 2489 CHILDINFO if at least one matching child is not also being returned. 2490 That is, servers SHOULD suppress redundant CHILDINFO responses. 2492 Examples 8 and 10 in Section 6.3.9.8 demonstrate the difference 2493 between present CHILDINFO extended data item and the "\HasChildren" 2494 attribute. 2496 The following table summarizes interaction between the "\NonExistent" 2497 attribute and CHILDINFO (the first column indicates whether the 2498 parent mailbox exists): 2500 +--------+-------------+------------------+-------------------------+ 2501 | exists | meets the | has a child that | returned | 2502 | | selection | meets the | IMAP4rev2/LIST-EXTENDED | 2503 | | criteria | selection | attributes and | 2504 | | | criteria | CHILDINFO | 2505 +--------+-------------+------------------+-------------------------+ 2506 | no | no | no | no LIST response | 2507 | | | | returned | 2508 | yes | no | no | no LIST response | 2509 | | | | returned | 2510 | no | yes | no | (\NonExistent ) | 2511 | yes | yes | no | () | 2512 | no | no | yes | (\NonExistent) + | 2513 | | | | CHILDINFO | 2514 | yes | no | yes | () + CHILDINFO | 2515 | no | yes | yes | (\NonExistent ) + | 2516 | | | | CHILDINFO | 2517 | yes | yes | yes | () + CHILDINFO | 2518 +--------+-------------+------------------+-------------------------+ 2520 where is one or more attributes that correspond to the 2521 selection criteria; for example, for the SUBSCRIBED option the 2522 is \Subscribed. 2524 6.3.9.7. OLDNAME Extended Data Item 2526 The OLDNAME extended data item is included when a mailbox name is 2527 created (with CREATE command), renamed (with RENAME command) or 2528 deleted (with DELETE command). (When a mailbox is deleted the 2529 "\NonExistent" attribute is also included.) IMAP extensions can 2530 specify other conditions when OLDNAME extended data item should be 2531 included. 2533 If the server allows de-normalized mailbox names (see Section 5.1) in 2534 SELECT/EXAMINE, CREATE, RENAME or DELETE, it SHOULD return an 2535 unsolicited LIST response that includes OLDNAME extended data item, 2536 whenever the supplied mailbox name differs from the resulting 2537 normalized mailbox name. From the client point of view this is 2538 indistinguishable from another user renaming or deleting the mailbox, 2539 as specified in the previous paragraph. 2541 A deleted mailbox can be announced like this: 2543 S: * LIST (\NonExistent) "." "INBOX.DeletedMailbox" 2545 Example of a renamed mailbox: 2547 S: * LIST () "/" "NewMailbox" ("OLDNAME" ("OldMailbox")) 2549 6.3.9.8. LIST Command Examples 2551 This example shows some uses of the basic LIST command: 2553 Example: C: A101 LIST "" "" 2554 S: * LIST (\Noselect) "/" "" 2555 S: A101 OK LIST Completed 2556 C: A102 LIST #news.comp.mail.misc "" 2557 S: * LIST (\Noselect) "." #news. 2558 S: A102 OK LIST Completed 2559 C: A103 LIST /usr/staff/jones "" 2560 S: * LIST (\Noselect) "/" / 2561 S: A103 OK LIST Completed 2562 C: A202 LIST ~/Mail/ % 2563 S: * LIST (\Noselect) "/" ~/Mail/foo 2564 S: * LIST () "/" ~/Mail/meetings 2565 S: A202 OK LIST completed 2567 Extended examples: 2569 1: The first example shows the complete local hierarchy that will 2570 be used for the other examples. 2572 C: A01 LIST "" "*" 2573 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2574 S: * LIST () "/" "Fruit" 2575 S: * LIST () "/" "Fruit/Apple" 2576 S: * LIST () "/" "Fruit/Banana" 2577 S: * LIST () "/" "Tofu" 2578 S: * LIST () "/" "Vegetable" 2579 S: * LIST () "/" "Vegetable/Broccoli" 2580 S: * LIST () "/" "Vegetable/Corn" 2581 S: A01 OK done 2583 2: In the next example, we will see the subscribed mailboxes. This 2584 is similar to, but not equivalent with now deprecated, (see [RFC3501] for more details on LSUB command). Note 2586 that the mailbox called "Fruit/Peach" is subscribed to, but does 2587 not actually exist (perhaps it was deleted while still 2588 subscribed). The "Fruit" mailbox is not subscribed to, but it 2589 has two subscribed children. The "Vegetable" mailbox is 2590 subscribed and has two children; one of them is subscribed as 2591 well. 2593 C: A02 LIST (SUBSCRIBED) "" "*" 2594 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2595 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2596 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2597 S: * LIST (\Subscribed) "/" "Vegetable" 2598 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2599 S: A02 OK done 2601 3: The next example shows the use of the CHILDREN option. The 2602 client, without having to list the second level of hierarchy, 2603 now knows which of the top-level mailboxes have submailboxes 2604 (children) and which do not. Note that it's not necessary for 2605 the server to return the \HasNoChildren attribute for the inbox, 2606 because the \NoInferiors attribute already implies that, and has 2607 a stronger meaning. 2609 C: A03 LIST () "" "%" RETURN (CHILDREN) 2610 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2611 S: * LIST (\HasChildren) "/" "Fruit" 2612 S: * LIST (\HasNoChildren) "/" "Tofu" 2613 S: * LIST (\HasChildren) "/" "Vegetable" 2614 S: A03 OK done 2616 4: In this example, we see more mailboxes that reside on another 2617 server. This is similar to the command . 2619 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 2620 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2621 S: * LIST (\HasChildren) "/" "Fruit" 2622 S: * LIST (\HasNoChildren) "/" "Tofu" 2623 S: * LIST (\HasChildren) "/" "Vegetable" 2624 S: * LIST (\Remote) "/" "Bread" 2625 S: * LIST (\HasChildren \Remote) "/" "Meat" 2626 S: A04 OK done 2628 5: The following example also requests the server to include 2629 mailboxes that reside on another server. The server returns 2630 information about all mailboxes that are subscribed. This is 2631 similar to the command (see [RFC2193] for more 2632 details on RLSUB). We also see the use of two selection 2633 options. 2635 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 2636 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2637 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2638 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2639 S: * LIST (\Subscribed) "/" "Vegetable" 2640 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2641 S: * LIST (\Remote \Subscribed) "/" "Bread" 2642 S: A05 OK done 2644 6: The following example requests the server to include mailboxes 2645 that reside on another server. The server is asked to return 2646 subscription information for all returned mailboxes. This is 2647 different from the example above. 2649 Note that the output of this command is not a superset of the 2650 output in the previous example, as it doesn't include LIST 2651 response for the non-existent "Fruit/Peach". 2653 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 2654 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2655 S: * LIST () "/" "Fruit" 2656 S: * LIST () "/" "Fruit/Apple" 2657 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2658 S: * LIST () "/" "Tofu" 2659 S: * LIST (\Subscribed) "/" "Vegetable" 2660 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2661 S: * LIST () "/" "Vegetable/Corn" 2662 S: * LIST (\Remote \Subscribed) "/" "Bread" 2663 S: * LIST (\Remote) "/" "Meat" 2664 S: A06 OK done 2666 7: The following example demonstrates the difference between the 2667 \HasChildren attribute and the CHILDINFO extended data item. 2669 Let's assume there is the following hierarchy: 2671 C: C01 LIST "" "*" 2672 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2673 S: * LIST () "/" "Foo" 2674 S: * LIST () "/" "Foo/Bar" 2675 S: * LIST () "/" "Foo/Baz" 2676 S: * LIST () "/" "Moo" 2677 S: C01 OK done 2679 If the client asks RETURN (CHILDREN), it will get this: 2681 C: CA3 LIST "" "%" RETURN (CHILDREN) 2682 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2683 S: * LIST (\HasChildren) "/" "Foo" 2684 S: * LIST (\HasNoChildren) "/" "Moo" 2685 S: CA3 OK done 2687 A) Let's also assume that the mailbox "Foo/Baz" is the only 2688 subscribed mailbox. Then we get this result: 2690 C: C02 LIST (SUBSCRIBED) "" "*" 2691 S: * LIST (\Subscribed) "/" "Foo/Baz" 2692 S: C02 OK done 2694 Now, if the client issues , the server 2695 will return no mailboxes (as the mailboxes "Moo", "Foo", and 2696 "Inbox" are NOT subscribed). However, if the client issues 2697 this: 2699 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2700 S: * LIST () "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2701 S: C04 OK done 2703 (i.e., the mailbox "Foo" is not subscribed, but it has a child 2704 that is.) 2706 A1) If the mailbox "Foo" had also been subscribed, the last 2707 command would return this: 2709 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2710 S: * LIST (\Subscribed) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2711 S: C04 OK done 2713 or even this: 2715 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2716 S: * LIST (\Subscribed \HasChildren) "/" "Foo" ("CHILDINFO" 2717 ("SUBSCRIBED")) 2718 S: C04 OK done 2720 A2) If we assume instead that the mailbox "Foo" is not part of 2721 the original hierarchy and is not subscribed, the last command 2722 will give this result: 2724 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2725 S: * LIST (\NonExistent) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2726 S: C04 OK done 2728 B) Now, let's assume that no mailbox is subscribed. In this 2729 case, the command will 2730 return no responses, as there are no subscribed children (even 2731 though "Foo" has children). 2733 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 2734 are subscribed. In that case, we see this result: 2736 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 2737 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 2738 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 2739 S: C04 OK done 2741 (which means that the mailbox "Foo" has children, but none of 2742 them is subscribed). 2744 8: The following example demonstrates that the CHILDINFO extended 2745 data item is returned whether or not children mailboxes match 2746 the canonical LIST pattern. 2748 Let's assume there is the following hierarchy: 2750 C: D01 LIST "" "*" 2751 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2752 S: * LIST () "/" "foo2" 2753 S: * LIST () "/" "foo2/bar1" 2754 S: * LIST () "/" "foo2/bar2" 2755 S: * LIST () "/" "baz2" 2756 S: * LIST () "/" "baz2/bar2" 2757 S: * LIST () "/" "baz2/bar22" 2758 S: * LIST () "/" "baz2/bar222" 2759 S: * LIST () "/" "eps2" 2760 S: * LIST () "/" "eps2/mamba" 2761 S: * LIST () "/" "qux2/bar2" 2762 S: D01 OK done 2763 And that the following mailboxes are subscribed: 2765 C: D02 LIST (SUBSCRIBED) "" "*" 2766 S: * LIST (\Subscribed) "/" "foo2/bar1" 2767 S: * LIST (\Subscribed) "/" "foo2/bar2" 2768 S: * LIST (\Subscribed) "/" "baz2/bar2" 2769 S: * LIST (\Subscribed) "/" "baz2/bar22" 2770 S: * LIST (\Subscribed) "/" "baz2/bar222" 2771 S: * LIST (\Subscribed) "/" "eps2" 2772 S: * LIST (\Subscribed) "/" "eps2/mamba" 2773 S: * LIST (\Subscribed) "/" "qux2/bar2" 2774 S: D02 OK done 2776 The client issues the following command first: 2778 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 2779 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2780 S: * LIST (\Subscribed) "/" "foo2/bar2" 2781 S: * LIST (\Subscribed) "/" "baz2/bar2" 2782 S: * LIST (\Subscribed) "/" "baz2/bar22" 2783 S: * LIST (\Subscribed) "/" "baz2/bar222" 2784 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2785 S: * LIST (\Subscribed) "/" "qux2/bar2" 2786 S: D03 OK done 2788 and the server may also include (but this would violate a SHOULD 2789 NOT in Section 3.5, because CHILDINFO is redundant) 2791 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2792 S: * LIST (\NonExistent) "/" "qux2" ("CHILDINFO" ("SUBSCRIBED")) 2794 The CHILDINFO extended data item is returned for mailboxes 2795 "foo2", "baz2", and "eps2", because all of them have subscribed 2796 children, even though for the mailbox "foo2" only one of the two 2797 subscribed children matches the pattern, for the mailbox "baz2" 2798 all the subscribed children match the pattern, and for the 2799 mailbox "eps2" none of the subscribed children matches the 2800 pattern. 2802 Note that if the client issues 2804 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 2805 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2806 S: * LIST (\Subscribed) "/" "foo2/bar1" 2807 S: * LIST (\Subscribed) "/" "foo2/bar2" 2808 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2809 S: * LIST (\Subscribed) "/" "baz2/bar2" 2810 S: * LIST (\Subscribed) "/" "baz2/bar22" 2811 S: * LIST (\Subscribed) "/" "baz2/bar222" 2812 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2813 S: * LIST (\Subscribed) "/" "eps2/mamba" 2814 S: * LIST (\Subscribed) "/" "qux2/bar2" 2815 S: D03 OK done 2817 The LIST responses for mailboxes "foo2", "baz2", and "eps2" 2818 still have the CHILDINFO extended data item, even though this 2819 information is redundant and the client can determine it by 2820 itself. 2822 9: The following example shows usage of extended syntax for mailbox 2823 pattern. It also demonstrates that the presence of the 2824 CHILDINFO extended data item doesn't necessarily imply 2825 \HasChildren. 2827 C: a1 LIST "" ("foo") 2828 S: * LIST () "/" foo 2829 S: a1 OK done 2831 C: a2 LIST (SUBSCRIBED) "" "foo/*" 2832 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 2833 S: a2 OK done 2835 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN (CHILDREN) 2836 S: * LIST (\HasNoChildren) "/" foo ("CHILDINFO" ("SUBSCRIBED")) 2837 S: a3 OK done 2839 10: The following example shows how a server that supports missing 2840 mailbox hierarchy elements can signal to a client that didn't 2841 specify the RECURSIVEMATCH selection option that there is a 2842 child mailbox that matches the selection criteria. 2844 C: a1 LIST (REMOTE) "" * 2845 S: * LIST () "/" music/rock 2846 S: * LIST (\Remote) "/" also/jazz 2847 S: a1 OK done 2849 C: a2 LIST () "" % 2850 S: * LIST (\NonExistent \HasChildren) "/" music 2851 S: a2 OK done 2853 C: a3 LIST (REMOTE) "" % 2854 S: * LIST (\NonExistent \HasChildren) "/" music 2855 S: * LIST (\NonExistent \HasChildren) "/" also 2856 S: a3 OK done 2858 C: a3.1 LIST "" (% music/rock) 2859 S: * LIST () "/" music/rock 2860 S: a3.1 OK done 2862 Because "music/rock" is the only mailbox under "music", there's 2863 no need for the server to also return "music". However clients 2864 must handle both cases. 2866 11: The following examples show use of STATUS return option. 2868 C: A01 LIST "" % RETURN (STATUS (MESSAGES UNSEEN)) 2869 S: * LIST () "." "INBOX" 2870 S: * STATUS "INBOX" (MESSAGES 17 UNSEEN 16) 2871 S: * LIST () "." "foo" 2872 S: * STATUS "foo" (MESSAGES 30 UNSEEN 29) 2873 S: * LIST (\NoSelect) "." "bar" 2874 S: A01 OK List completed. 2876 The "bar" mailbox isn't selectable, so it has no STATUS reply. 2878 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (STATUS 2879 (MESSAGES)) 2880 S: * LIST (\Subscribed) "." "INBOX" 2881 S: * STATUS "INBOX" (MESSAGES 17) 2882 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED")) 2883 S: A02 OK List completed. 2885 The LIST reply for "foo" is returned because it has matching 2886 children, but no STATUS reply is returned because "foo" itself 2887 doesn't match the selection criteria. 2889 6.3.10. NAMESPACE Command 2891 Arguments: none 2893 Responses: REQUIRED untagged responses: NAMESPACE 2895 Result: OK - command completed 2896 NO - Can't complete the command 2897 BAD - arguments invalid 2899 The NAMESPACE command causes a single untagged NAMESPACE response to 2900 be returned. The untagged NAMESPACE response contains the prefix and 2901 hierarchy delimiter to the server's Personal Namespace(s), Other 2902 Users' Namespace(s), and Shared Namespace(s) that the server wishes 2903 to expose. The response will contain a NIL for any namespace class 2904 that is not available. The Namespace-Response-Extensions ABNF non 2905 terminal is defined for extensibility and MAY be included in the 2906 NAMESPACE response. 2908 Example 1: 2910 In this example a server supports a single personal namespace. No 2911 leading prefix is used on personal mailboxes and "/" is the hierarchy 2912 delimiter. 2914 C: A001 NAMESPACE 2915 S: * NAMESPACE (("" "/")) NIL NIL 2916 S: A001 OK NAMESPACE command completed 2918 Example 2: 2920 A user logged on anonymously to a server. No personal mailboxes are 2921 associated with the anonymous user and the user does not have access 2922 to the Other Users' Namespace. No prefix is required to access 2923 shared mailboxes and the hierarchy delimiter is "." 2925 C: A001 NAMESPACE 2926 S: * NAMESPACE NIL NIL (("" ".")) 2927 S: A001 OK NAMESPACE command completed 2929 Example 3: 2931 A server that contains a Personal Namespace and a single Shared 2932 Namespace. 2934 C: A001 NAMESPACE 2935 S: * NAMESPACE (("" "/")) NIL (("Public Folders/" "/")) 2936 S: A001 OK NAMESPACE command completed 2938 Example 4: 2940 A server that contains a Personal Namespace, Other Users' Namespace 2941 and multiple Shared Namespaces. Note that the hierarchy delimiter 2942 used within each namespace can be different. 2944 C: A001 NAMESPACE 2945 S: * NAMESPACE (("" "/")) (("~" "/")) (("#shared/" "/") 2946 ("#public/" "/")("#ftp/" "/")("#news." ".")) 2947 S: A001 OK NAMESPACE command completed 2949 The prefix string allows a client to do things such as automatically 2950 creating personal mailboxes or LISTing all available mailboxes within 2951 a namespace. 2953 Example 5: 2955 A server that supports only the Personal Namespace, with a leading 2956 prefix of INBOX to personal mailboxes and a hierarchy delimiter of 2957 "." 2959 C: A001 NAMESPACE 2960 S: * NAMESPACE (("INBOX." ".")) NIL NIL 2961 S: A001 OK NAMESPACE command completed 2963 < Automatically create a mailbox to store sent items.> 2965 C: A002 CREATE "INBOX.Sent Mail" 2966 S: A002 OK CREATE command completed 2968 Although typically a server will support only a single Personal 2969 Namespace, and a single Other User's Namespace, circumstances exist 2970 where there MAY be multiples of these, and a client MUST be prepared 2971 for them. If a client is configured such that it is required to 2972 create a certain mailbox, there can be circumstances where it is 2973 unclear which Personal Namespaces it should create the mailbox in. 2974 In these situations a client SHOULD let the user select which 2975 namespaces to create the mailbox in or just use the first personal 2976 namespace. 2978 Example 6: 2980 In this example, a server supports two Personal Namespaces. In 2981 addition to the regular Personal Namespace, the user has an 2982 additional personal namespace to allow access to mailboxes in an MH 2983 format mailstore. 2985 The client is configured to save a copy of all mail sent by the user 2986 into a mailbox called 'Sent Mail'. Furthermore, after a message is 2987 deleted from a mailbox, the client is configured to move that message 2988 to a mailbox called 'Deleted Items'. 2990 Note that this example demonstrates how some extension parameters can 2991 be passed to further describe the #mh namespace. See the fictitious 2992 "X-PARAM" extension parameter. 2994 C: A001 NAMESPACE 2995 S: * NAMESPACE (("" "/")("#mh/" "/" "X-PARAM" 2996 ("FLAG1" "FLAG2"))) NIL NIL 2997 S: A001 OK NAMESPACE command completed 2999 < It is desired to keep only one copy of sent mail. 3000 It is unclear which Personal Namespace the client 3001 should use to create the 'Sent Mail' mailbox. 3002 The user is prompted to select a namespace and only 3003 one 'Sent Mail' mailbox is created. > 3005 C: A002 CREATE "Sent Mail" 3006 S: A002 OK CREATE command completed 3008 < The client is designed so that it keeps two 3009 'Deleted Items' mailboxes, one for each namespace. > 3011 C: A003 CREATE "Delete Items" 3012 S: A003 OK CREATE command completed 3014 C: A004 CREATE "#mh/Deleted Items" 3015 S: A004 OK CREATE command completed 3017 The next level of hierarchy following the Other Users' Namespace 3018 prefix SHOULD consist of , where is a user name 3019 as per the LOGIN or AUTHENTICATE command. 3021 A client can construct a LIST command by appending a "%" to the Other 3022 Users' Namespace prefix to discover the Personal Namespaces of other 3023 users that are available to the currently authenticated user. 3025 In response to such a LIST command, a server SHOULD NOT return user 3026 names that have not granted access to their personal mailboxes to the 3027 user in question. 3029 A server MAY return a LIST response containing only the names of 3030 users that have explicitly granted access to the user in question. 3032 Alternatively, a server MAY return NO to such a LIST command, 3033 requiring that a user name be included with the Other Users' 3034 Namespace prefix before listing any other user's mailboxes. 3036 Example 7: 3038 A server that supports providing a list of other user's mailboxes 3039 that are accessible to the currently logged on user. 3041 C: A001 NAMESPACE 3042 S: * NAMESPACE (("" "/")) (("Other Users/" "/")) NIL 3043 S: A001 OK NAMESPACE command completed 3045 C: A002 LIST "" "Other Users/%" 3046 S: * LIST () "/" "Other Users/Mike" 3047 S: * LIST () "/" "Other Users/Karen" 3048 S: * LIST () "/" "Other Users/Matthew" 3049 S: * LIST () "/" "Other Users/Tesa" 3050 S: A002 OK LIST command completed 3052 Example 8: 3054 A server that does not support providing a list of other user's 3055 mailboxes that are accessible to the currently logged on user. The 3056 mailboxes are listable if the client includes the name of the other 3057 user with the Other Users' Namespace prefix. 3059 C: A001 NAMESPACE 3060 S: * NAMESPACE (("" "/")) (("#Users/" "/")) NIL 3061 S: A001 OK NAMESPACE command completed 3063 < In this example, the currently logged on user has access to 3064 the Personal Namespace of user Mike, but the server chose to 3065 suppress this information in the LIST response. However, 3066 by appending the user name Mike (received through user input) 3067 to the Other Users' Namespace prefix, the client is able 3068 to get a listing of the personal mailboxes of user Mike. > 3070 C: A002 LIST "" "#Users/%" 3071 S: A002 NO The requested item could not be found. 3073 C: A003 LIST "" "#Users/Mike/%" 3074 S: * LIST () "/" "#Users/Mike/INBOX" 3075 S: * LIST () "/" "#Users/Mike/Foo" 3076 S: A003 OK LIST command completed. 3078 A prefix string might not contain a hierarchy delimiter, because in 3079 some cases it is not needed as part of the prefix. 3081 Example 9: 3083 A server that allows access to the Other Users' Namespace by 3084 prefixing the others' mailboxes with a '~' followed by , 3085 where is a user name as per the LOGIN or AUTHENTICATE 3086 command. 3088 C: A001 NAMESPACE 3089 S: * NAMESPACE (("" "/")) (("~" "/")) NIL 3090 S: A001 OK NAMESPACE command completed 3092 < List the mailboxes for user mark > 3094 C: A002 LIST "" "~mark/%" 3095 S: * LIST () "/" "~mark/INBOX" 3096 S: * LIST () "/" "~mark/foo" 3097 S: A002 OK LIST command completed 3099 6.3.11. STATUS Command 3101 Arguments: mailbox name 3102 status data item names 3104 Responses: REQUIRED untagged responses: STATUS 3106 Result: OK - status completed 3107 NO - status failure: no status for that name 3108 BAD - command unknown or arguments invalid 3110 The STATUS command requests the status of the indicated mailbox. It 3111 does not change the currently selected mailbox, nor does it affect 3112 the state of any messages in the queried mailbox. 3114 The STATUS command provides an alternative to opening a second 3115 IMAP4rev2 connection and doing an EXAMINE command on a mailbox to 3116 query that mailbox's status without deselecting the current mailbox 3117 in the first IMAP4rev2 connection. 3119 Unlike the LIST command, the STATUS command is not guaranteed to be 3120 fast in its response. Under certain circumstances, it can be quite 3121 slow. In some implementations, the server is obliged to open the 3122 mailbox read-only internally to obtain certain status information. 3123 Also unlike the LIST command, the STATUS command does not accept 3124 wildcards. 3126 Note: The STATUS command is intended to access the status of 3127 mailboxes other than the currently selected mailbox. Because the 3128 STATUS command can cause the mailbox to be opened internally, and 3129 because this information is available by other means on the 3130 selected mailbox, the STATUS command SHOULD NOT be used on the 3131 currently selected mailbox. However, servers MUST be able to 3132 execute STATUS command on the selected mailbox. (This might also 3133 implicitly happen when STATUS return option is used in a LIST 3134 command). 3136 The STATUS command MUST NOT be used as a "check for new messages 3137 in the selected mailbox" operation (refer to Section 7 and 3138 Section 7.3.1 for more information about the proper method for new 3139 message checking). 3141 STATUS SIZE (see below) can take a significant amount of time, 3142 depending upon server implementation. Clients should use STATUS 3143 SIZE cautiously. 3145 The currently defined status data items that can be requested are: 3147 MESSAGES The number of messages in the mailbox. 3149 UIDNEXT The next unique identifier value of the mailbox. Refer to 3150 Section 2.3.1.1 for more information. 3152 UIDVALIDITY The unique identifier validity value of the mailbox. 3153 Refer to Section 2.3.1.1 for more information. 3155 UNSEEN The number of messages which do not have the \Seen flag set. 3157 DELETED The number of messages which have the \Deleted flag set. 3159 SIZE The total size of the mailbox in octets. This is not strictly 3160 required to be an exact value, but it MUST be equal to or greater 3161 than the sum of the values of the RFC822.SIZE FETCH message data 3162 items (see Section 6.4.5) of all messages in the mailbox. 3164 Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES) 3165 S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 3166 S: A042 OK STATUS completed 3168 6.3.12. APPEND Command 3170 Arguments: mailbox name 3171 OPTIONAL flag parenthesized list 3172 OPTIONAL date/time string 3173 message literal 3175 Responses: OPTIONAL untagged response: LIST 3176 Result: OK - append completed 3177 NO - append error: can't append to that mailbox, error 3178 in flags or date/time or message text 3179 BAD - command unknown or arguments invalid 3181 The APPEND command appends the literal argument as a new message to 3182 the end of the specified destination mailbox. This argument SHOULD 3183 be in the format of an [RFC-5322] or [I18N-HDRS] message. 8-bit 3184 characters are permitted in the message. A server implementation 3185 that is unable to preserve 8-bit data properly MUST be able to 3186 reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB] 3187 content transfer encoding. 3189 Note: There may be exceptions, e.g., draft messages, in which 3190 required [RFC-5322] header fields are omitted in the message 3191 literal argument to APPEND. The full implications of doing so 3192 must be understood and carefully weighed. 3194 If a flag parenthesized list is specified, the flags SHOULD be set in 3195 the resulting message; otherwise, the flag list of the resulting 3196 message is set to empty by default. 3198 If a date-time is specified, the internal date SHOULD be set in the 3199 resulting message; otherwise, the internal date of the resulting 3200 message is set to the current date and time by default. 3202 If the append is unsuccessful for any reason, the mailbox MUST be 3203 restored to its state before the APPEND attempt (other than possibly 3204 keeping the changed mailbox's UIDNEXT value); no partial appending is 3205 permitted. 3207 If the destination mailbox does not exist, a server MUST return an 3208 error, and MUST NOT automatically create the mailbox. Unless it is 3209 certain that the destination mailbox can not be created, the server 3210 MUST send the response code "[TRYCREATE]" as the prefix of the text 3211 of the tagged NO response. This gives a hint to the client that it 3212 can attempt a CREATE command and retry the APPEND if the CREATE is 3213 successful. 3215 On successful completion of an APPEND, the server SHOULD return an 3216 APPENDUID response code (see Section 7.1). 3218 In the case of a mailbox that has permissions set so that the client 3219 can APPEND to the mailbox, but not SELECT or EXAMINE it, the server 3220 SHOULD NOT send an APPENDUID response code as it would disclose 3221 information about the mailbox. 3223 In the case of a mailbox that has UIDNOTSTICKY status (see 3224 Section 7.1), the server MAY omit the APPENDUID response code as it 3225 is not meaningful. 3227 If the server does not return the APPENDUID response codes, the 3228 client can discover this information by selecting the destination 3229 mailbox. The location of messages placed in the destination mailbox 3230 by APPEND can be determined by using FETCH and/or SEARCH commands 3231 (e.g., for Message-ID or some unique marker placed in the message in 3232 an APPEND). 3234 If the mailbox is currently selected, the normal new message actions 3235 SHOULD occur. Specifically, the server SHOULD notify the client 3236 immediately via an untagged EXISTS response. If the server does not 3237 do so, the client MAY issue a NOOP command after one or more APPEND 3238 commands. 3240 If the server decides to convert (normalize) the mailbox name, it 3241 SHOULD return an untagged LIST with OLDNAME extended data item, with 3242 the OLDNAME value being the supplied mailbox name and the name 3243 parameter being the normalized mailbox name. (See Section 6.3.9.7 3244 for more details.) 3246 Example: C: A003 APPEND saved-messages (\Seen) {310} 3247 S: + Ready for literal data 3248 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3249 C: From: Fred Foobar 3250 C: Subject: afternoon meeting 3251 C: To: mooch@owatagu.siam.edu 3252 C: Message-Id: 3253 C: MIME-Version: 1.0 3254 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3255 C: 3256 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3257 C: 3258 S: A003 OK APPEND completed 3260 Example: C: A003 APPEND saved-messages (\Seen) {297} 3261 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3262 C: From: Fred Foobar 3263 C: Subject: afternoon meeting 3264 C: To: mooch@example.com 3265 C: Message-Id: 3266 C: MIME-Version: 1.0 3267 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3268 C: 3269 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3270 C: 3271 S: A003 OK [APPENDUID 38505 3955] APPEND completed 3272 C: A004 COPY 2:4 meeting 3273 S: A004 OK [COPYUID 38505 304,319:320 3956:3958] Done 3274 C: A005 UID COPY 305:310 meeting 3275 S: A005 OK No matching messages, so nothing copied 3276 C: A006 COPY 2 funny 3277 S: A006 OK Done 3278 C: A007 SELECT funny 3279 S: * 1 EXISTS 3280 S: * OK [UIDVALIDITY 3857529045] Validity session-only 3281 S: * OK [UIDNEXT 2] Predicted next UID 3282 S: * NO [UIDNOTSTICKY] Non-persistent UIDs 3283 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 3284 S: * OK [PERMANENTFLAGS (\Deleted \Seen)] Limited 3285 S: * LIST () "." funny 3286 S: A007 OK [READ-WRITE] SELECT completed 3288 In this example, A003 and A004 demonstrate successful appending and 3289 copying to a mailbox that returns the UIDs assigned to the messages. 3290 A005 is an example in which no messages were copied; this is because 3291 in A003, we see that message 2 had UID 304, and message 3 had UID 3292 319; therefore, UIDs 305 through 310 do not exist (refer to 3293 Section 2.3.1.1 for further explanation). A006 is an example of a 3294 message being copied that did not return a COPYUID; and, as expected, 3295 A007 shows that the mail store containing that mailbox does not 3296 support persistent UIDs. 3298 Note: The APPEND command is not used for message delivery, because 3299 it does not provide a mechanism to transfer [SMTP] envelope 3300 information. 3302 6.3.13. IDLE Command 3304 Arguments: none 3306 Responses: continuation data will be requested; the client sends the 3307 continuation data "DONE" to end the command 3309 Result: OK - IDLE completed after client sent "DONE" 3310 NO - failure: the server will not allow the IDLE command 3311 at this time 3312 BAD - command unknown or arguments invalid 3314 Without the IDLE command a client would need to poll the server for 3315 changes to the selected mailbox (new mail, deletions, flag changes). 3316 It's often more desirable to have the server transmit updates to the 3317 client in real time. This allows a user to see new mail immediately. 3318 The IDLE command allows a client to tell the server that it's ready 3319 to accept such real-time updates. 3321 The IDLE command is sent from the client to the server when the 3322 client is ready to accept unsolicited update messages. The server 3323 requests a response to the IDLE command using the continuation ("+") 3324 response. The IDLE command remains active until the client responds 3325 to the continuation, and as long as an IDLE command is active, the 3326 server is now free to send untagged EXISTS, EXPUNGE, FETCH, and other 3327 responses at any time. If the server chooses to send unsolicited 3328 FETCH responses, they MUST include UID FETCH item. 3330 The IDLE command is terminated by the receipt of a "DONE" 3331 continuation from the client; such response satisfies the server's 3332 continuation request. At that point, the server MAY send any 3333 remaining queued untagged responses and then MUST immediately send 3334 the tagged response to the IDLE command and prepare to process other 3335 commands. As for other commands, the processing of any new command 3336 may cause the sending of unsolicited untagged responses, subject to 3337 the ambiguity limitations. The client MUST NOT send a command while 3338 the server is waiting for the DONE, since the server will not be able 3339 to distinguish a command from a continuation. 3341 The server MAY consider a client inactive if it has an IDLE command 3342 running, and if such a server has an inactivity timeout it MAY log 3343 the client off implicitly at the end of its timeout period. Because 3344 of that, clients using IDLE are advised to terminate the IDLE and re- 3345 issue it at least every 29 minutes to avoid being logged off. This 3346 still allows a client to receive immediate mailbox updates even 3347 though it need only "poll" at half hour intervals. 3349 Example: C: A001 SELECT INBOX 3350 S: * FLAGS (\Deleted \Seen \Flagged) 3351 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Flagged)] Limited 3352 S: * 3 EXISTS 3353 S: * OK [UIDVALIDITY 1] 3354 S: * LIST () "/" INBOX 3355 S: A001 OK [READ-WRITE] SELECT completed 3356 C: A002 IDLE 3357 S: + idling 3358 ...time passes; new mail arrives... 3359 S: * 4 EXISTS 3360 C: DONE 3361 S: A002 OK IDLE terminated 3362 ...another client expunges message 2 now... 3363 C: A003 FETCH 4 ALL 3364 S: * 4 FETCH (...) 3365 S: A003 OK FETCH completed 3366 C: A004 IDLE 3367 S: * 2 EXPUNGE 3368 S: * 3 EXISTS 3369 S: + idling 3370 ...time passes; another client expunges message 3... 3371 S: * 3 EXPUNGE 3372 S: * 2 EXISTS 3373 ...time passes; new mail arrives... 3374 S: * 3 EXISTS 3375 C: DONE 3376 S: A004 OK IDLE terminated 3377 C: A005 FETCH 3 ALL 3378 S: * 3 FETCH (...) 3379 S: A005 OK FETCH completed 3380 C: A006 IDLE 3382 6.4. Client Commands - Selected State 3384 In the selected state, commands that manipulate messages in a mailbox 3385 are permitted. 3387 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 3388 and the authenticated state commands (SELECT, EXAMINE, NAMESPACE, 3389 CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, STATUS, and 3390 APPEND), the following commands are valid in the selected state: 3391 CLOSE, UNSELECT, EXPUNGE, SEARCH, FETCH, STORE, COPY, MOVE, and UID. 3393 6.4.1. CLOSE Command 3395 Arguments: none 3397 Responses: no specific responses for this command 3399 Result: OK - close completed, now in authenticated state 3400 BAD - command unknown or arguments invalid 3402 The CLOSE command permanently removes all messages that have the 3403 \Deleted flag set from the currently selected mailbox, and returns to 3404 the authenticated state from the selected state. No untagged EXPUNGE 3405 responses are sent. 3407 No messages are removed, and no error is given, if the mailbox is 3408 selected by an EXAMINE command or is otherwise selected read-only. 3410 Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT command 3411 MAY be issued without previously issuing a CLOSE command. The 3412 SELECT, EXAMINE, and LOGOUT commands implicitly close the currently 3413 selected mailbox without doing an expunge. However, when many 3414 messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT sequence is 3415 considerably faster than an EXPUNGE-LOGOUT or EXPUNGE-SELECT because 3416 no untagged EXPUNGE responses (which the client would probably 3417 ignore) are sent. 3419 Example: C: A341 CLOSE 3420 S: A341 OK CLOSE completed 3422 6.4.2. UNSELECT Command 3424 Arguments: none 3426 Responses: no specific responses for this command 3428 Result: OK - unselect completed, now in authenticated state 3429 BAD - no mailbox selected, or argument supplied but none 3430 permitted 3432 The UNSELECT command frees session's resources associated with the 3433 selected mailbox and returns the server to the authenticated state. 3434 This command performs the same actions as CLOSE, except that no 3435 messages are permanently removed from the currently selected mailbox. 3437 Example: C: A342 UNSELECT 3438 S: A342 OK Unselect completed 3440 6.4.3. EXPUNGE Command 3442 Arguments: none 3444 Responses: untagged responses: EXPUNGE 3446 Result: OK - expunge completed 3447 NO - expunge failure: can't expunge (e.g., permission 3448 denied) 3449 BAD - command unknown or arguments invalid 3451 The EXPUNGE command permanently removes all messages that have the 3452 \Deleted flag set from the currently selected mailbox. Before 3453 returning an OK to the client, an untagged EXPUNGE response is sent 3454 for each message that is removed. 3456 Example: C: A202 EXPUNGE 3457 S: * 3 EXPUNGE 3458 S: * 3 EXPUNGE 3459 S: * 5 EXPUNGE 3460 S: * 8 EXPUNGE 3461 S: A202 OK EXPUNGE completed 3463 Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag 3464 set. See the description of the EXPUNGE response (Section 7.4.1) for 3465 further explanation. 3467 6.4.4. SEARCH Command 3469 Arguments: OPTIONAL result specifier 3470 OPTIONAL [CHARSET] specification 3471 searching criteria (one or more) 3473 Responses: OPTIONAL untagged response: ESEARCH 3475 Result: OK - search completed 3476 NO - search error: can't search that [CHARSET] or 3477 criteria 3478 BAD - command unknown or arguments invalid 3480 The SEARCH command searches the mailbox for messages that match the 3481 given searching criteria. 3483 The SEARCH command may contain result options. Result options 3484 control what kind of information is returned about messages matching 3485 the search criteria in an untagged ESEARCH response. If no result 3486 option is specified or empty list of options is specified "()", ALL 3487 is assumed (see below). The order of individual options is 3488 arbitrary. Individual options may contain parameters enclosed in 3489 parentheses. (However, if an option has a mandatory parameter, which 3490 can always be represented as a number or a sequence-set, the option 3491 parameter does not need the enclosing parentheses. See the Formal 3492 Syntax (Section 9) for more details). If an option has parameters, 3493 they consist of atoms and/or strings and/or lists in a specific 3494 order. Any options not defined by extensions that the server 3495 supports MUST be rejected with a BAD response. 3497 This document specifies the following result options: 3499 MIN 3501 Return the lowest message number/UID that satisfies the SEARCH 3502 criteria. 3504 If the SEARCH results in no matches, the server MUST NOT 3505 include the MIN result option in the ESEARCH response; however, 3506 it still MUST send the ESEARCH response. 3508 MAX 3510 Return the highest message number/UID that satisfies the SEARCH 3511 criteria. 3513 If the SEARCH results in no matches, the server MUST NOT 3514 include the MAX result option in the ESEARCH response; however, 3515 it still MUST send the ESEARCH response. 3517 ALL 3519 Return all message numbers/UIDs that satisfy the SEARCH 3520 criteria using the sequence-set syntax. Note, the client MUST 3521 NOT assume that messages/UIDs will be listed in any particular 3522 order. 3524 If the SEARCH results in no matches, the server MUST NOT 3525 include the ALL result option in the ESEARCH response; however, 3526 it still MUST send the ESEARCH response. 3528 COUNT Return the number of messages that satisfy the SEARCH 3529 criteria. This result option MUST always be included in the 3530 ESEARCH response. 3532 SAVE 3534 This option tells the server to remember the result of the 3535 SEARCH or UID SEARCH command (as well as any command based on 3536 SEARCH, e.g., SORT and THREAD [RFC5256]>) and store it in an 3537 internal variable that we will reference as the "search result 3538 variable". The client can use the "$" marker to reference the 3539 content of this internal variable. The "$" marker can be used 3540 instead of message sequence or UID sequence in order to 3541 indicate that the server should substitute it with the list of 3542 messages from the search result variable. Thus, the client can 3543 use the result of the latest remembered SEARCH command as a 3544 parameter to another command. See Section 6.4.4.1 for details 3545 on how the value of the search result variable is determined, 3546 how it is affected by other commands executed, and how SAVE 3547 return option interacts with other return options. 3549 In absence of any other SEARCH result option, the SAVE result 3550 option also suppresses any ESEARCH response that would have 3551 been otherwise returned by the SEARCH command. 3553 Note: future extensions to this document can allow servers to return 3554 multiple ESEARCH responses for a single extended SEARCH command. 3555 However all options specified above MUST result in a single ESEARCH 3556 response if used by themselves or in a combination. This guaranty 3557 simplifies processing in IMAP4rev2 clients. Future SEARCH extensions 3558 that relax this restriction will have to describe how results from 3559 multiple ESEARCH responses are to be amalgamated. 3561 Searching criteria consist of one or more search keys. 3563 When multiple keys are specified, the result is the intersection (AND 3564 function) of all the messages that match those keys. For example, 3565 the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers to all 3566 deleted messages from Smith with INTERNALDATE greater than February 3567 1, 1994. A search key can also be a parenthesized list of one or 3568 more search keys (e.g., for use with the OR and NOT keys). 3570 Server implementations MAY exclude [MIME-IMB] body parts with 3571 terminal content media types other than TEXT and MESSAGE from 3572 consideration in SEARCH matching. 3574 The OPTIONAL [CHARSET] specification consists of the word "CHARSET" 3575 followed by a registered [CHARSET] [CHARSET-REG]. It indicates the 3576 [CHARSET] of the strings that appear in the search criteria. 3577 [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in 3578 [RFC-5322]/[MIME-IMB] headers, MUST be decoded before comparing text. 3579 Servers MUST support US-ASCII and UTF-8 charsets; other [CHARSET]s 3580 MAY be supported. Clients SHOULD use UTF-8. Note that if "CHARSET" 3581 is not provided IMAP4rev2 server MUST assume UTF-8, so selecting 3582 CHARSET UTF-8 is redundant. It is permitted for improved 3583 compatibility with existing IMAP4rev1 clients. 3585 If the server does not support the specified [CHARSET], it MUST 3586 return a tagged NO response (not a BAD). This response SHOULD 3587 contain the BADCHARSET response code, which MAY list the [CHARSET]s 3588 supported by the server. 3590 In all search keys that use strings and unless specified otherwise, a 3591 message matches the key if the string is a substring of the 3592 associated text. The matching SHOULD be case-insensitive for 3593 characters within ASCII range. Consider using [IMAP-I18N] for 3594 language-sensitive case-insensitive searching. Note that the empty 3595 string is a substring; this is useful when doing a HEADER search in 3596 order to test for a header field presence in the message. 3598 The defined search keys are as follows. Refer to the Formal Syntax 3599 section for the precise syntactic definitions of the arguments. 3601 Messages with message sequence numbers corresponding 3602 to the specified message sequence number set. 3604 ALL All messages in the mailbox; the default initial key for ANDing. 3606 ANSWERED Messages with the \Answered flag set. 3608 BCC Messages that contain the specified string in the 3609 envelope structure's BCC field. 3611 BEFORE Messages whose internal date (disregarding time and 3612 timezone) is earlier than the specified date. 3614 BODY Messages that contain the specified string in the body 3615 of the message. Unlike TEXT (see below), this doesn't match any 3616 header fields. Servers are allowed to implement flexible matching 3617 for this search key, for example matching "swim" to both "swam" 3618 and "swum" in English language text or only doing full word 3619 matching (where "swim" will not match "swimming"). 3621 CC Messages that contain the specified string in the 3622 envelope structure's CC field. 3624 DELETED Messages with the \Deleted flag set. 3626 DRAFT Messages with the \Draft flag set. 3628 FLAGGED Messages with the \Flagged flag set. 3630 FROM Messages that contain the specified string in the 3631 envelope structure's FROM field. 3633 HEADER Messages that have a header field with 3634 the specified field-name (as defined in [RFC-5322]) and that 3635 contains the specified string in the text of the header field 3636 (what comes after the colon). If the string to search is zero- 3637 length, this matches all messages that have a header field with 3638 the specified field-name regardless of the contents. Servers 3639 should use substring search for this SEARCH item, as clients can 3640 use it for automatic processing not initiated by end users. For 3641 example this can be used for searching for Message-ID or Content- 3642 Type header field values that need to be exact, or for searches in 3643 header fields that the IMAP server might not know anything about. 3645 KEYWORD Messages with the specified keyword flag set. 3647 LARGER Messages with an [RFC-5322] size larger than the 3648 specified number of octets. 3650 NOT Messages that do not match the specified search 3651 key. 3653 ON Messages whose internal date (disregarding time and 3654 timezone) is within the specified date. 3656 OR Messages that match either search 3657 key. 3659 SEEN Messages that have the \Seen flag set. 3661 SENTBEFORE Messages whose [RFC-5322] Date: header field 3662 (disregarding time and timezone) is earlier than the specified 3663 date. 3665 SENTON Messages whose [RFC-5322] Date: header field 3666 (disregarding time and timezone) is within the specified date. 3668 SENTSINCE Messages whose [RFC-5322] Date: header field 3669 (disregarding time and timezone) is within or later than the 3670 specified date. 3672 SINCE Messages whose internal date (disregarding time and 3673 timezone) is within or later than the specified date. 3675 SMALLER Messages with an [RFC-5322] size smaller than the 3676 specified number of octets. 3678 SUBJECT Messages that contain the specified string in the 3679 envelope structure's SUBJECT field. 3681 TEXT Messages that contain the specified string in the 3682 header (including MIME header fields) or body of the message. 3683 Servers are allowed to implement flexible matching for this search 3684 key, for example matching "swim" to both "swam" and "swum" in 3685 English language text or only doing full word matching (where 3686 "swim" will not match "swimming"). 3688 TO Messages that contain the specified string in the 3689 envelope structure's TO field. 3691 UID Messages with unique identifiers corresponding to 3692 the specified unique identifier set. Sequence set ranges are 3693 permitted. 3695 UNANSWERED Messages that do not have the \Answered flag set. 3697 UNDELETED Messages that do not have the \Deleted flag set. 3699 UNDRAFT Messages that do not have the \Draft flag set. 3701 UNFLAGGED Messages that do not have the \Flagged flag set. 3703 UNKEYWORD Messages that do not have the specified keyword 3704 flag set. 3706 UNSEEN Messages that do not have the \Seen flag set. 3708 Example: C: A282 SEARCH RETURN (MIN COUNT) FLAGGED 3709 SINCE 1-Feb-1994 NOT FROM "Smith" 3710 S: * ESEARCH (TAG "A282") MIN 2 COUNT 3 3711 S: A282 OK SEARCH completed 3713 Example: C: A283 SEARCH RETURN () FLAGGED 3714 SINCE 1-Feb-1994 NOT FROM "Smith" 3715 S: * ESEARCH (TAG "A283") ALL 2,10:11 3716 S: A283 OK SEARCH completed 3718 Example: C: A284 SEARCH TEXT "string not in mailbox" 3719 S: * ESEARCH (TAG "A284") 3720 S: A284 OK SEARCH completed 3721 C: A285 SEARCH CHARSET UTF-8 TEXT {6} 3722 S: + Ready for literal text 3723 C: XXXXXX 3724 S: * ESEARCH (TAG "A285") ALL 43 3725 S: A285 OK SEARCH completed 3727 Note: Since this document is restricted to 7-bit ASCII text, it is 3728 not possible to show actual UTF-8 data. The "XXXXXX" is a 3729 placeholder for what would be 6 octets of 8-bit data in an actual 3730 transaction. 3732 The following example demonstrates finding the first unseen message 3733 in the mailbox: 3735 Example: C: A284 SEARCH RETURN (MIN) UNSEEN 3736 S: * ESEARCH (TAG "A284") MIN 4 3737 S: A284 OK SEARCH completed 3739 The following example demonstrates that if the ESEARCH UID indicator 3740 is present, all data in the ESEARCH response is referring to UIDs; 3741 for example, the MIN result specifier will be followed by a UID. 3743 Example: C: A285 UID SEARCH RETURN (MIN MAX) 1:5000 3744 S: * ESEARCH (TAG "A285") UID MIN 7 MAX 3800 3745 S: A285 OK SEARCH completed 3747 The following example demonstrates returning the number of deleted 3748 messages: 3750 Example: C: A286 SEARCH RETURN (COUNT) DELETED 3751 S: * ESEARCH (TAG "A286") COUNT 15 3752 S: A286 OK SEARCH completed 3754 6.4.4.1. SAVE result option and SEARCH result variable 3756 Upon successful completion of a SELECT or an EXAMINE command (after 3757 the tagged OK response), the current search result variable is reset 3758 to the empty sequence. 3760 A successful SEARCH command with the SAVE result option sets the 3761 value of the search result variable to the list of messages found in 3762 the SEARCH command. For example, if no messages were found, the 3763 search result variable will contain the empty sequence. 3765 Any of the following SEARCH commands MUST NOT change the search 3766 result variable: 3768 a SEARCH command that caused the server to return the BAD tagged 3769 response, 3771 a SEARCH command with no SAVE result option that caused the server 3772 to return NO tagged response, 3774 a successful SEARCH command with no SAVE result option. 3776 A SEARCH command with the SAVE result option that caused the server 3777 to return the NO tagged response sets the value of the search result 3778 variable to the empty sequence. 3780 When a message listed in the search result variable is EXPUNGEd, it 3781 is automatically removed from the list. Implementors are reminded 3782 that if the server stores the list as a list of message numbers, it 3783 MUST automatically adjust them when notifying the client about 3784 expunged messages, as described in Section 7.4.1. 3786 If the server decides to send a new UIDVALIDITY value while the 3787 mailbox is opened, this causes resetting of the search variable to 3788 the empty sequence. 3790 Note that even if the "$" marker contains the empty sequence of 3791 messages, it must be treated by all commands accepting message sets 3792 as parameters as a valid, but non-matching list of messages. For 3793 example, the "FETCH $" command would return a tagged OK response and 3794 no FETCH responses. See also the Example 5 in Section 6.4.4.4. 3796 The SAVE result option doesn't change whether the server would return 3797 items corresponding to MIN, MAX, ALL, or COUNT result options. 3799 When the SAVE result option is combined with the MIN or MAX result 3800 option, and both ALL and COUNT result options are absent, the 3801 corresponding MIN/MAX is returned (if the search result is not 3802 empty), but the "$" marker would contain a single message as returned 3803 in the MIN/MAX return item. 3805 If the SAVE result option is combined with both MIN and MAX result 3806 options, and both ALL and COUNT result options are absent, the "$" 3807 marker would contain zero, one or two messages as returned in the 3808 MIN/MAX return items. 3810 If the SAVE result option is combined with the ALL and/or COUNT 3811 result option(s), the "$" marker would always contain all messages 3812 found by the SEARCH or UID SEARCH command. 3814 The following table summarizes the additional requirement on ESEARCH 3815 server implementations described in this section. 3817 +------------------------------+--------------------+ 3818 | Combination of Result option | "$" marker value | 3819 +------------------------------+--------------------+ 3820 | SAVE MIN | MIN | 3821 | SAVE MAX | MAX | 3822 | SAVE MIN MAX | MIN & MAX | 3823 | SAVE * [m] | all found messages | 3824 +------------------------------+--------------------+ 3826 where '*' means "ALL" and/or "COUNT", and '[m]' means optional "MIN" 3827 and/or "MAX" 3829 Implementation note: server implementors should note that "$" can 3830 reference IMAP message sequences or UID sequences, depending on the 3831 context where it is used. For example, the "$" marker can be set as 3832 a result of a SEARCH (SAVE) command and used as a parameter to a UID 3833 FETCH command (which accepts a UID sequence, not a message sequence), 3834 or the "$" marker can be set as a result of a UID SEARCH (SAVE) 3835 command and used as a parameter to a FETCH command (which accepts a 3836 message sequence, not a UID sequence). Server implementations need 3837 to automatically map the "$" marker value to message numbers or UIDs, 3838 depending on context where the "$" marker is used. 3840 6.4.4.2. Multiple Commands in Progress 3842 Use of a SEARCH RETURN (SAVE) command followed by a command using the 3843 "$" marker creates direct dependency between the two commands. As 3844 directed by Section 5.5, a server MUST execute the two commands in 3845 the order they were received. 3847 A client MAY pipeline a SEARCH RETURN (SAVE) command with one or more 3848 command using the "$" marker, as long as this doesn't create an 3849 ambiguity, as described in Section 5.5. Examples 7-9 in 3850 Section 6.4.4.4 explain this in more details. 3852 6.4.4.3. Refusing to Save Search Results 3854 In some cases, the server MAY refuse to save a SEARCH (SAVE) result, 3855 for example, if an internal limit on the number of saved results is 3856 reached. In this case, the server MUST return a tagged NO response 3857 containing the NOTSAVED response code and set the search result 3858 variable to the empty sequence, as described in Section 6.4.4.1. 3860 6.4.4.4. Examples showing use of SAVE result option 3862 Only in this section: explanatory comments in examples that start 3863 with // are not part of the protocol. 3865 1) The following example demonstrates how the client can use the 3866 result of a SEARCH command to FETCH headers of interesting messages: 3868 Example 1: 3869 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3870 NOT FROM "Smith" 3871 S: A282 OK SEARCH completed, result saved 3872 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3873 S: * 2 FETCH (UID 14 ... 3874 S: * 84 FETCH (UID 100 ... 3875 S: * 882 FETCH (UID 1115 ... 3876 S: A283 OK completed 3878 The client can also pipeline the two commands: 3880 Example 2: 3881 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3882 NOT FROM "Smith" 3883 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3884 S: A282 OK SEARCH completed 3885 S: * 2 FETCH (UID 14 ... 3886 S: * 84 FETCH (UID 100 ... 3887 S: * 882 FETCH (UID 1115 ... 3888 S: A283 OK completed 3890 2) The following example demonstrates that the result of one SEARCH 3891 command can be used as input to another SEARCH command: 3893 Example 3: 3894 C: A300 SEARCH RETURN (SAVE) SINCE 1-Jan-2004 3895 NOT FROM "Smith" 3896 S: A300 OK SEARCH completed 3897 C: A301 UID SEARCH UID $ SMALLER 4096 3898 S: * ESEARCH (TAG "A301") UID ALL 17,900,901 3899 S: A301 OK completed 3901 Note that the second command in Example 3 can be replaced with: 3902 C: A301 UID SEARCH $ SMALLER 4096 3903 and the result of the command would be the same. 3905 3) The following example shows that the "$" marker can be combined 3906 with other message numbers using the OR SEARCH criterion. 3908 Example 4: 3909 C: P282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3910 NOT FROM "Smith" 3911 S: P282 OK SEARCH completed 3912 C: P283 SEARCH CHARSET UTF-8 (OR $ 1,3000:3021) TEXT {8} 3913 C: YYYYYYYY 3914 S: * ESEARCH (TAG "P283") ALL 882,1102,3003,3005:3006 3915 S: P283 OK completed 3917 Note: Since this document format is restricted to 7-bit ASCII text, 3918 it is not possible to show actual UTF-8 data. The "YYYYYYYY" is a 3919 placeholder for what would be 8 octets of 8-bit data in an actual 3920 transaction. 3922 4) The following example demonstrates that a failed SEARCH sets the 3923 search result variable to the empty list. The server doesn't 3924 implement the KOI8-R charset. 3926 Example 5: 3927 C: B282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3928 NOT FROM "Smith" 3929 S: B282 OK SEARCH completed 3930 C: B283 SEARCH RETURN (SAVE) CHARSET KOI8-R 3931 (OR $ 1,3000:3021) TEXT {4} 3932 C: XXXX 3933 S: B283 NO [BADCHARSET UTF-8] KOI8-R is not supported 3934 //After this command the saved result variable contains 3935 //no messages. A client that wants to reissue the B283 3936 //SEARCH command with another CHARSET would have to reissue 3937 //the B282 command as well. One possible workaround for 3938 //this is to include the desired CHARSET parameter 3939 //in the earliest SEARCH RETURN (SAVE) command in a 3940 //sequence of related SEARCH commands, to cause 3941 //the earliest SEARCH in the sequence to fail. 3942 //A better approach might be to always use CHARSET UTF-8 3943 //instead. 3945 Note: Since this document format is restricted to 7-bit ASCII text, 3946 it is not possible to show actual KOI8-R data. The "XXXX" is a 3947 placeholder for what would be 4 octets of 8-bit data in an actual 3948 transaction. 3950 5) The following example demonstrates that it is not an error to use 3951 the "$" marker when it contains no messages. 3953 Example 6: 3954 C: E282 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3955 NOT FROM "Eric" 3956 C: E283 COPY $ "Other Messages" 3957 //The "$" contains no messages 3958 S: E282 OK SEARCH completed 3959 S: E283 OK COPY completed, nothing copied 3961 Example 7: 3962 C: F282 SEARCH RETURN (SAVE) KEYWORD $Junk 3963 C: F283 COPY $ "Junk" 3964 C: F284 STORE $ +FLAGS.Silent (\Deleted) 3965 S: F282 OK SEARCH completed 3966 S: F283 OK COPY completed 3967 S: F284 OK STORE completed 3969 Example 8: 3970 C: G282 SEARCH RETURN (SAVE) KEYWORD $Junk 3971 C: G283 SEARCH RETURN (ALL) SINCE 28-Oct-2006 3972 FROM "Eric" 3973 // The server can execute the two SEARCH commands 3974 // in any order, as they don't have any dependency. 3975 // For example, it may return: 3976 S: * ESEARCH (TAG "G283") ALL 3:15,27,29:103 3977 S: G283 OK SEARCH completed 3978 S: G282 OK SEARCH completed 3980 The following example demonstrates that the result of the second 3981 SEARCH RETURN (SAVE) always overrides the result of the first. 3983 Example 9: 3984 C: H282 SEARCH RETURN (SAVE) KEYWORD $Junk 3985 C: H283 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3986 FROM "Eric" 3987 S: H282 OK SEARCH completed 3988 S: H283 OK SEARCH completed 3989 // At this point "$" would contain results of H283 3991 The following example demonstrates behavioral difference for 3992 different combinations of ESEARCH result options. 3994 Example 10: 3995 C: C282 SEARCH RETURN (ALL) SINCE 12-Feb-2006 3996 NOT FROM "Smith" 3997 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3998 //$ value hasn't changed 3999 S: C282 OK SEARCH completed 4001 C: C283 SEARCH RETURN (ALL SAVE) SINCE 12-Feb-2006 4002 NOT FROM "Smith" 4003 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 4004 //$ value is 2,10:15,21 4005 S: C283 OK SEARCH completed 4007 C: C284 SEARCH RETURN (SAVE MIN) SINCE 12-Feb-2006 4008 NOT FROM "Smith" 4009 S: * ESEARCH (TAG "C284") MIN 2 4010 //$ value is 2 4011 S: C284 OK SEARCH completed 4013 C: C285 SEARCH RETURN (MAX SAVE MIN) SINCE 4014 12-Feb-2006 NOT FROM "Smith" 4015 S: * ESEARCH (TAG "C285") MIN 2 MAX 21 4016 //$ value is 2,21 4017 S: C285 OK SEARCH completed 4019 C: C286 SEARCH RETURN (MAX SAVE MIN COUNT) 4020 SINCE 12-Feb-2006 NOT FROM "Smith" 4021 S: * ESEARCH (TAG "C286") MIN 2 MAX 21 COUNT 8 4022 //$ value is 2,10:15,21 4023 S: C286 OK SEARCH completed 4025 C: C286 SEARCH RETURN (ALL SAVE MIN) SINCE 4026 12-Feb-2006 NOT FROM "Smith" 4027 S: * ESEARCH (TAG "C286") MIN 2 ALL 2,10:15,21 4028 //$ value is 2,10:15,21 4029 S: C286 OK SEARCH completed 4031 6.4.5. FETCH Command 4033 Arguments: sequence set 4034 message data item names or macro 4036 Responses: untagged responses: FETCH 4038 Result: OK - fetch completed 4039 NO - fetch error: can't fetch that data 4040 BAD - command unknown or arguments invalid 4042 The FETCH command retrieves data associated with a message in the 4043 mailbox. The data items to be fetched can be either a single atom or 4044 a parenthesized list. 4046 Most data items, identified in the formal syntax (Section 9) under 4047 the msg-att-static rule, are static and MUST NOT change for any 4048 particular message. Other data items, identified in the formal 4049 syntax under the msg-att-dynamic rule, MAY change, either as a result 4050 of a STORE command or due to external events. 4052 For example, if a client receives an ENVELOPE for a message when 4053 it already knows the envelope, it can safely ignore the newly 4054 transmitted envelope. 4056 There are three macros which specify commonly-used sets of data 4057 items, and can be used instead of data items. A macro must be used 4058 by itself, and not in conjunction with other macros or data items. 4060 ALL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE) 4062 FAST Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE) 4064 FULL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE 4065 BODY) 4067 Several data items reference "section" or "section-binary". See 4068 Section 6.4.5.1 for their detailed definition. 4070 The currently defined data items that can be fetched are: 4072 BINARY[]<> 4074 Requests that the specified section be transmitted after 4075 performing Content-Transfer-Encoding-related decoding. 4077 The argument, if present, requests that a subset of 4078 the data be returned. The semantics of a partial FETCH BINARY 4079 command are the same as for a partial FETCH BODY command, with 4080 the exception that the arguments refer to the DECODED 4081 section data. 4083 Note that this data item can only be requested for leaf (i.e. 4084 non multipart/*, non message/rfc822 and non message/global) 4085 body parts. 4087 BINARY.PEEK[]<> An alternate form of 4088 BINARY[] that does not implicitly set the \Seen 4089 flag. 4091 BINARY.SIZE[] 4093 Requests the decoded size of the section (i.e., the size to 4094 expect in response to the corresponding FETCH BINARY request). 4096 Note: client authors are cautioned that this might be an 4097 expensive operation for some server implementations. 4098 Needlessly issuing this request could result in degraded 4099 performance due to servers having to calculate the value every 4100 time the request is issued. 4102 Note that this data item can only be requested for leaf (i.e. 4103 non multipart/*, non message/rfc822 and non message/global) 4104 body parts. 4106 BODY Non-extensible form of BODYSTRUCTURE. 4108 BODY[
]<> 4110 The text of a particular body section. 4112 It is possible to fetch a substring of the designated text. 4113 This is done by appending an open angle bracket ("<"), the 4114 octet position of the first desired octet, a period, the 4115 maximum number of octets desired, and a close angle bracket 4116 (">") to the part specifier. If the starting octet is beyond 4117 the end of the text, an empty string is returned. 4119 Any partial fetch that attempts to read beyond the end of the 4120 text is truncated as appropriate. A partial fetch that starts 4121 at octet 0 is returned as a partial fetch, even if this 4122 truncation happened. 4124 Note: This means that BODY[]<0.2048> of a 1500-octet message 4125 will return BODY[]<0> with a literal of size 1500, not 4126 BODY[]. 4128 Note: A substring fetch of a HEADER.FIELDS or 4129 HEADER.FIELDS.NOT part specifier is calculated after 4130 subsetting the header. 4132 The \Seen flag is implicitly set; if this causes the flags to 4133 change, they SHOULD be included as part of the FETCH responses. 4135 BODY.PEEK[
]<> An alternate form of BODY[
] 4136 that does not implicitly set the \Seen flag. 4138 BODYSTRUCTURE The [MIME-IMB] body structure of the message. This is 4139 computed by the server by parsing the [MIME-IMB] header fields in 4140 the [RFC-5322] header and [MIME-IMB] headers. See Section 7.4.2 4141 for more details. 4143 ENVELOPE The envelope structure of the message. This is computed by 4144 the server by parsing the [RFC-5322] header into the component 4145 parts, defaulting various fields as necessary. See Section 7.4.2 4146 for more details. 4148 FLAGS The flags that are set for this message. 4150 INTERNALDATE The internal date of the message. 4152 RFC822.SIZE The [RFC-5322] size of the message. 4154 UID The unique identifier for the message. 4156 Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)]) 4157 S: * 2 FETCH .... 4158 S: * 3 FETCH .... 4159 S: * 4 FETCH .... 4160 S: A654 OK FETCH completed 4162 6.4.5.1. FETCH section specification 4164 Several FETCH data items reference "section" or "section-binary". 4165 The section specification is a set of zero or more part specifiers 4166 delimited by periods. A part specifier is either a part number or 4167 one of the following: HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, 4168 and TEXT. (Non numeric part specifiers have to be the last specifier 4169 in a section specification.) An empty section specification refers 4170 to the entire message, including the header. 4172 Every message has at least one part number. Non-[MIME-IMB] messages, 4173 and non-multipart [MIME-IMB] messages with no encapsulated message, 4174 only have a part 1. 4176 Multipart messages are assigned consecutive part numbers, as they 4177 occur in the message. If a particular part is of type message or 4178 multipart, its parts MUST be indicated by a period followed by the 4179 part number within that nested multipart part. 4181 A part of type MESSAGE/RFC822 or MESSAGE/GLOBAL also has nested part 4182 numbers, referring to parts of the MESSAGE part's body. 4184 The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part 4185 specifiers can be the sole part specifier or can be prefixed by one 4186 or more numeric part specifiers, provided that the numeric part 4187 specifier refers to a part of type MESSAGE/RFC822 or MESSAGE/GLOBAL. 4188 The MIME part specifier MUST be prefixed by one or more numeric part 4189 specifiers. 4191 The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part specifiers 4192 refer to the [RFC-5322] header of the message or of an encapsulated 4193 [MIME-IMT] MESSAGE/RFC822 or MESSAGE/GLOBAL message. HEADER.FIELDS 4194 and HEADER.FIELDS.NOT are followed by a list of field-name (as 4195 defined in [RFC-5322]) names, and return a subset of the header. The 4196 subset returned by HEADER.FIELDS contains only those header fields 4197 with a field-name that matches one of the names in the list; 4198 similarly, the subset returned by HEADER.FIELDS.NOT contains only the 4199 header fields with a non-matching field-name. The field-matching is 4200 ASCII range case-insensitive but otherwise exact. Subsetting does 4201 not exclude the [RFC-5322] delimiting blank line between the header 4202 and the body; the blank line is included in all header fetches, 4203 except in the case of a message which has no body and no blank line. 4205 The MIME part specifier refers to the [MIME-IMB] header for this 4206 part. 4208 The TEXT part specifier refers to the text body of the message, 4209 omitting the [RFC-5322] header. 4211 Here is an example of a complex message with some of its part 4212 specifiers: 4214 HEADER ([RFC-5322] header of the message) 4215 TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4216 1 TEXT/PLAIN 4217 2 APPLICATION/OCTET-STREAM 4218 3 MESSAGE/RFC822 4219 3.HEADER ([RFC-5322] header of the message) 4220 3.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4221 3.1 TEXT/PLAIN 4222 3.2 APPLICATION/OCTET-STREAM 4223 4 MULTIPART/MIXED 4224 4.1 IMAGE/GIF 4225 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF) 4226 4.2 MESSAGE/RFC822 4227 4.2.HEADER ([RFC-5322] header of the message) 4228 4.2.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4229 4.2.1 TEXT/PLAIN 4230 4.2.2 MULTIPART/ALTERNATIVE 4231 4.2.2.1 TEXT/PLAIN 4232 4.2.2.2 TEXT/RICHTEXT 4234 6.4.6. STORE Command 4236 Arguments: sequence set 4237 message data item name 4238 value for message data item 4240 Responses: untagged responses: FETCH 4242 Result: OK - store completed 4243 NO - store error: can't store that data 4244 BAD - command unknown or arguments invalid 4246 The STORE command alters data associated with a message in the 4247 mailbox. Normally, STORE will return the updated value of the data 4248 with an untagged FETCH response. A suffix of ".SILENT" in the data 4249 item name prevents the untagged FETCH, and the server SHOULD assume 4250 that the client has determined the updated value itself or does not 4251 care about the updated value. 4253 Note: Regardless of whether or not the ".SILENT" suffix was used, 4254 the server SHOULD send an untagged FETCH response if a change to a 4255 message's flags from an external source is observed. The intent 4256 is that the status of the flags is determinate without a race 4257 condition. 4259 The currently defined data items that can be stored are: 4261 FLAGS Replace the flags for the message with the 4262 argument. The new value of the flags is returned as if a FETCH of 4263 those flags was done. 4265 FLAGS.SILENT Equivalent to FLAGS, but without returning 4266 a new value. 4268 +FLAGS Add the argument to the flags for the message. 4269 The new value of the flags is returned as if a FETCH of those 4270 flags was done. 4272 +FLAGS.SILENT Equivalent to +FLAGS, but without 4273 returning a new value. 4275 -FLAGS Remove the argument from the flags for the 4276 message. The new value of the flags is returned as if a FETCH of 4277 those flags was done. 4279 -FLAGS.SILENT Equivalent to -FLAGS, but without 4280 returning a new value. 4282 Example: C: A003 STORE 2:4 +FLAGS (\Deleted) 4283 S: * 2 FETCH (FLAGS (\Deleted \Seen)) 4284 S: * 3 FETCH (FLAGS (\Deleted)) 4285 S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen)) 4286 S: A003 OK STORE completed 4288 6.4.7. COPY Command 4290 Arguments: sequence set 4291 mailbox name 4293 Responses: no specific responses for this command 4295 Result: OK - copy completed 4296 NO - copy error: can't copy those messages or to that 4297 name 4298 BAD - command unknown or arguments invalid 4300 The COPY command copies the specified message(s) to the end of the 4301 specified destination mailbox. The flags and internal date of the 4302 message(s) SHOULD be preserved in the copy. 4304 If the destination mailbox does not exist, a server SHOULD return an 4305 error. It SHOULD NOT automatically create the mailbox. Unless it is 4306 certain that the destination mailbox can not be created, the server 4307 MUST send the response code "[TRYCREATE]" as the prefix of the text 4308 of the tagged NO response. This gives a hint to the client that it 4309 can attempt a CREATE command and retry the COPY if the CREATE is 4310 successful. 4312 If the COPY command is unsuccessful for any reason, server 4313 implementations MUST restore the destination mailbox to its state 4314 before the COPY attempt. 4316 On successful completion of a COPY, the server SHOULD return a 4317 COPYUID response code (see Section 7.1). 4319 In the case of a mailbox that has permissions set so that the client 4320 can COPY to the mailbox, but not SELECT or EXAMINE it, the server 4321 SHOULD NOT send an COPYUID response code as it would disclose 4322 information about the mailbox. 4324 In the case of a mailbox that has UIDNOTSTICKY status (see 4325 Section 7.1), the server MAY omit the COPYUID response code as it is 4326 not meaningful. 4328 If the server does not return the COPYUID response code, the client 4329 can discover this information by selecting the destination mailbox. 4331 The location of messages placed in the destination mailbox by COPY 4332 can be determined by using FETCH and/or SEARCH commands (e.g., for 4333 Message-ID). 4335 Example: C: A003 COPY 2:4 MEETING 4336 S: A003 OK COPY completed 4338 6.4.8. MOVE Command 4340 Arguments: sequence set 4341 mailbox name 4343 Responses: no specific responses for this command 4345 Result: OK - move completed 4346 NO - move error: can't move those messages or to that 4347 name 4348 BAD - command unknown or arguments invalid 4350 The MOVE command moves the specified message(s) to the end of the 4351 specified destination mailbox. The flags and internal date of the 4352 message(s) SHOULD be preserved. 4354 This means that a new message is created in the target mailbox with a 4355 new UID, the original message is removed from the source mailbox, and 4356 it appears to the client as a single action. This has the same 4357 effect for each message as this sequence: 4359 1. [UID] COPY 4361 2. [UID] STORE +FLAGS.SILENT \DELETED 4363 3. UID EXPUNGE 4365 Although the effect of the MOVE is the same as the preceding steps, 4366 the semantics are not identical: The intermediate states produced by 4367 those steps do not occur, and the response codes are different. In 4368 particular, though the COPY and EXPUNGE response codes will be 4369 returned, response codes for a STORE MUST NOT be generated and the 4370 \Deleted flag MUST NOT be set for any message. 4372 Because a MOVE applies to a set of messages, it might fail partway 4373 through the set. Regardless of whether the command is successful in 4374 moving the entire set, each individual message SHOULD either be moved 4375 or unaffected. The server MUST leave each message in a state where 4376 it is in at least one of the source or target mailboxes (no message 4377 can be lost or orphaned). The server SHOULD NOT leave any message in 4378 both mailboxes (it would be bad for a partial failure to result in a 4379 bunch of duplicate messages). This is true even if the server 4380 returns a tagged NO response to the command. 4382 Because of the similarity of MOVE to COPY, extensions that affect 4383 COPY affect MOVE in the same way. Response codes such as TRYCREATE 4384 (see Section 7.1), as well as those defined by extensions, are sent 4385 as appropriate. 4387 Servers SHOULD send COPYUID in response to a UID MOVE (see 4388 Section 6.4.9) command. For additional information see Section 7.1. 4390 Servers are also advised to send the COPYUID response code in an 4391 untagged OK before sending EXPUNGE or moved responses. (Sending 4392 COPYUID in the tagged OK, as described in the UIDPLUS specification, 4393 means that clients first receive an EXPUNGE for a message and 4394 afterwards COPYUID for the same message. It can be unnecessarily 4395 difficult to process that sequence usefully.) 4397 An example: 4398 C: a UID MOVE 42:69 foo 4399 S: * OK [COPYUID 432432 42:69 1202:1229] 4400 S: * 22 EXPUNGE 4401 S: (more expunges) 4402 S: a OK Done 4404 Note that the server may send unrelated EXPUNGE responses as well, if 4405 any happen to have been expunged at the same time; this is normal 4406 IMAP operation. 4408 Note that moving a message to the currently selected mailbox (that 4409 is, where the source and target mailboxes are the same) is allowed 4410 when copying the message to the currently selected mailbox is 4411 allowed. 4413 The server may send EXPUNGE responses before the tagged response, so 4414 the client cannot safely send more commands with message sequence 4415 number arguments while the server is processing MOVE. 4417 MOVE and UID MOVE can be pipelined with other commands, but care has 4418 to be taken. Both commands modify sequence numbers and also allow 4419 unrelated EXPUNGE responses. The renumbering of other messages in 4420 the source mailbox following any EXPUNGE response can be surprising 4421 and makes it unsafe to pipeline any command that relies on message 4422 sequence numbers after a MOVE or UID MOVE. Similarly, MOVE cannot be 4423 pipelined with a command that might cause message renumbering. See 4424 Section 5.5, for more information about ambiguities as well as 4425 handling requirements for both clients and servers. 4427 6.4.9. UID Command 4429 Arguments: command name 4430 command arguments 4432 Responses: untagged responses: FETCH, ESEARCH, EXPUNGE 4434 Result: OK - UID command completed 4435 NO - UID command error 4436 BAD - command unknown or arguments invalid 4438 The UID command has three forms. In the first form, it takes as its 4439 arguments a COPY, MOVE, FETCH, or STORE command with arguments 4440 appropriate for the associated command. However, the numbers in the 4441 sequence set argument are unique identifiers instead of message 4442 sequence numbers. Sequence set ranges are permitted, but there is no 4443 guarantee that unique identifiers will be contiguous. 4445 A non-existent unique identifier is ignored without any error message 4446 generated. Thus, it is possible for a UID FETCH command to return an 4447 OK without any data or a UID COPY, UID MOVE or UID STORE to return an 4448 OK without performing any operations. 4450 In the second form, the UID command takes an EXPUNGE command with an 4451 extra parameter the specified a sequence set of UIDs to operate on. 4452 The UID EXPUNGE command permanently removes all messages that both 4453 have the \Deleted flag set and have a UID that is included in the 4454 specified sequence set from the currently selected mailbox. If a 4455 message either does not have the \Deleted flag set or has a UID that 4456 is not included in the specified sequence set, it is not affected. 4458 UID EXPUNGE is particularly useful for disconnected use clients. 4459 By using UID EXPUNGE instead of EXPUNGE when resynchronizing with 4460 the server, the client can ensure that it does not inadvertantly 4461 remove any messages that have been marked as \Deleted by other 4462 clients between the time that the client was last connected and 4463 the time the client resynchronizes. 4465 Example: C: A003 UID EXPUNGE 3000:3002 4466 S: * 3 EXPUNGE 4467 S: * 3 EXPUNGE 4468 S: * 3 EXPUNGE 4469 S: A003 OK UID EXPUNGE completed 4471 In the third form, the UID command takes a SEARCH command with SEARCH 4472 command arguments. The interpretation of the arguments is the same 4473 as with SEARCH; however, the numbers returned in a ESEARCH response 4474 for a UID SEARCH command are unique identifiers instead of message 4475 sequence numbers. Also, the corresponding ESEARCH response MUST 4476 include the UID indicator. For example, the command UID SEARCH 1:100 4477 UID 443:557 returns the unique identifiers corresponding to the 4478 intersection of two sequence sets, the message sequence number range 4479 1:100 and the UID range 443:557. 4481 Note: in the above example, the UID range 443:557 appears. The 4482 same comment about a non-existent unique identifier being ignored 4483 without any error message also applies here. Hence, even if 4484 neither UID 443 or 557 exist, this range is valid and would 4485 include an existing UID 495. 4487 Also note that a UID range of 559:* always includes the UID of the 4488 last message in the mailbox, even if 559 is higher than any 4489 assigned UID value. This is because the contents of a range are 4490 independent of the order of the range endpoints. Thus, any UID 4491 range with * as one of the endpoints indicates at least one 4492 message (the message with the highest numbered UID), unless the 4493 mailbox is empty. 4495 The number after the "*" in an untagged FETCH or EXPUNGE response is 4496 always a message sequence number, not a unique identifier, even for a 4497 UID command response. However, server implementations MUST 4498 implicitly include the UID message data item as part of any FETCH 4499 response caused by a UID command, regardless of whether a UID was 4500 specified as a message data item to the FETCH. 4502 Note: The rule about including the UID message data item as part of a 4503 FETCH response primarily applies to the UID FETCH and UID STORE 4504 commands, including a UID FETCH command that does not include UID as 4505 a message data item. Although it is unlikely that the other UID 4506 commands will cause an untagged FETCH, this rule applies to these 4507 commands as well. 4509 Example: C: A999 UID FETCH 4827313:4828442 FLAGS 4510 S: * 23 FETCH (FLAGS (\Seen) UID 4827313) 4511 S: * 24 FETCH (FLAGS (\Seen) UID 4827943) 4512 S: * 25 FETCH (FLAGS (\Seen) UID 4828442) 4513 S: A999 OK UID FETCH completed 4515 6.5. Client Commands - Experimental/Expansion 4517 Each command which is not part of this specification MUST have at 4518 least one capability name (see Section 6.1.1) associated with it. 4519 (Multiple commands can be associated with the same capability name) 4521 Server implementations MUST NOT send any added (not specified in this 4522 specification) untagged responses, unless the client requested it by 4523 issuing the associated experimental command or the ENABLE command 4524 (Section 6.3.1). 4526 The following example demonstrates how a client can check for 4527 presence of a fictitious XPIG-LATIN capability that adds the XPIG- 4528 LATIN command and the the XPIG-LATIN untagged response. (Note that 4529 for an extension the command name and the capability name don't have 4530 to be the same.) 4532 Example: C: a441 CAPABILITY 4533 S: * CAPABILITY IMAP4rev2 XPIG-LATIN 4534 S: a441 OK CAPABILITY completed 4535 C: A442 XPIG-LATIN 4536 S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay 4537 S: A442 OK XPIG-LATIN ompleted-cay 4539 7. Server Responses 4541 Server responses are in three forms: status responses, server data, 4542 and command continuation request. The information contained in a 4543 server response, identified by "Contents:" in the response 4544 descriptions below, is described by function, not by syntax. The 4545 precise syntax of server responses is described in the Formal Syntax 4546 (Section 9). 4548 The client MUST be prepared to accept any response at all times. 4550 Status responses can be tagged or untagged. Tagged status responses 4551 indicate the completion result (OK, NO, or BAD status) of a client 4552 command, and have a tag matching the command. 4554 Some status responses, and all server data, are untagged. An 4555 untagged response is indicated by the token "*" instead of a tag. 4556 Untagged status responses indicate server greeting, or server status 4557 that does not indicate the completion of a command (for example, an 4558 impending system shutdown alert). For historical reasons, untagged 4559 server data responses are also called "unsolicited data", although 4560 strictly speaking, only unilateral server data is truly 4561 "unsolicited". 4563 Certain server data MUST be recorded by the client when it is 4564 received; this is noted in the description of that data. Such data 4565 conveys critical information which affects the interpretation of all 4566 subsequent commands and responses (e.g., updates reflecting the 4567 creation or destruction of messages). 4569 Other server data SHOULD be recorded for later reference; if the 4570 client does not need to record the data, or if recording the data has 4571 no obvious purpose (e.g., a SEARCH response when no SEARCH command is 4572 in progress), the data SHOULD be ignored. 4574 An example of unilateral untagged server data occurs when the IMAP 4575 connection is in the selected state. In the selected state, the 4576 server checks the mailbox for new messages as part of command 4577 execution. Normally, this is part of the execution of every command; 4578 hence, a NOOP command suffices to check for new messages. If new 4579 messages are found, the server sends untagged EXISTS response 4580 reflecting the new size of the mailbox. Server implementations that 4581 offer multiple simultaneous access to the same mailbox SHOULD also 4582 send appropriate unilateral untagged FETCH and EXPUNGE responses if 4583 another agent changes the state of any message flags or expunges any 4584 messages. 4586 Command continuation request responses use the token "+" instead of a 4587 tag. These responses are sent by the server to indicate acceptance 4588 of an incomplete client command and readiness for the remainder of 4589 the command. 4591 7.1. Server Responses - Status Responses 4593 Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD 4594 can be tagged or untagged. PREAUTH and BYE are always untagged. 4596 Status responses MAY include an OPTIONAL "response code". A response 4597 code consists of data inside square brackets in the form of an atom, 4598 possibly followed by a space and arguments. The response code 4599 contains additional information or status codes for client software 4600 beyond the OK/NO/BAD condition, and are defined when there is a 4601 specific action that a client can take based upon the additional 4602 information. 4604 The currently defined response codes are: 4606 ALERT 4608 The human-readable text contains a special alert that MUST be 4609 presented to the user in a fashion that calls the user's 4610 attention to the message. 4612 ALREADYEXISTS 4614 The operation attempts to create something that already exists, 4615 such as when the CREATE or RENAME directories attempt to create 4616 a mailbox and there is already one of that name. 4618 C: o356 RENAME this that 4619 S: o356 NO [ALREADYEXISTS] Mailbox "that" already exists 4621 APPENDUID 4623 Followed by the UIDVALIDITY of the destination mailbox and the 4624 UID assigned to the appended message in the destination 4625 mailbox, indicates that the message has been appended to the 4626 destination mailbox with that UID. 4628 If the server also supports the [MULTIAPPEND] extension, and if 4629 multiple messages were appended in the APPEND command, then the 4630 second value is a UID set containing the UIDs assigned to the 4631 appended messages, in the order they were transmitted in the 4632 APPEND command. This UID set may not contain extraneous UIDs 4633 or the symbol "*". 4635 Note: the UID set form of the APPENDUID response code MUST 4636 NOT be used if only a single message was appended. In 4637 particular, a server MUST NOT send a range such as 123:123. 4638 This is because a client that does not support [MULTIAPPEND] 4639 expects only a single UID and not a UID set. 4641 UIDs are assigned in strictly ascending order in the mailbox 4642 (refer to Section 2.3.1.1); note that a range of 12:10 is 4643 exactly equivalent to 10:12 and refers to the sequence 4644 10,11,12. 4646 This response code is returned in a tagged OK response to the 4647 APPEND command. 4649 AUTHENTICATIONFAILED 4651 Authentication failed for some reason on which the server is 4652 unwilling to elaborate. Typically, this includes "unknown 4653 user" and "bad password". 4655 This is the same as not sending any response code, except that 4656 when a client sees AUTHENTICATIONFAILED, it knows that the 4657 problem wasn't, e.g., UNAVAILABLE, so there's no point in 4658 trying the same login/password again later. 4660 C: b LOGIN "fred" "foo" 4661 S: b NO [AUTHENTICATIONFAILED] Authentication failed 4663 AUTHORIZATIONFAILED 4664 Authentication succeeded in using the authentication identity, 4665 but the server cannot or will not allow the authentication 4666 identity to act as the requested authorization identity. This 4667 is only applicable when the authentication and authorization 4668 identities are different. 4670 C: c1 AUTHENTICATE PLAIN 4671 [...] 4672 S: c1 NO [AUTHORIZATIONFAILED] No such authorization-ID 4674 C: c2 AUTHENTICATE PLAIN 4675 [...] 4676 S: c2 NO [AUTHORIZATIONFAILED] Authenticator is not an admin 4678 BADCHARSET 4680 Optionally followed by a parenthesized list of charsets. A 4681 SEARCH failed because the given charset is not supported by 4682 this implementation. If the optional list of charsets is 4683 given, this lists the charsets that are supported by this 4684 implementation. 4686 CANNOT 4688 The operation violates some invariant of the server and can 4689 never succeed. 4691 C: l create "///////" 4692 S: l NO [CANNOT] Adjacent slashes are not supported 4694 CAPABILITY 4696 Followed by a list of capabilities. This can appear in the 4697 initial OK or PREAUTH response to transmit an initial 4698 capabilities list. It can also appear in tagged responses to 4699 LOGIN or AUTHENTICATE commands. This makes it unnecessary for 4700 a client to send a separate CAPABILITY command if it recognizes 4701 this response. 4703 CLIENTBUG 4705 The server has detected a client bug. This can accompany all 4706 of OK, NO, and BAD, depending on what the client bug is. 4708 C: k1 select "/archive/projects/experiment-iv" 4709 [...] 4710 S: k1 OK [READ-ONLY] Done 4711 C: k2 status "/archive/projects/experiment-iv" (messages) 4712 [...] 4713 S: k2 OK [CLIENTBUG] Done 4715 CLOSED 4717 The CLOSED response code has no parameters. A server return 4718 the CLOSED response code when the currently selected mailbox is 4719 closed implicitly using the SELECT/EXAMINE command on another 4720 mailbox. The CLOSED response code serves as a boundary between 4721 responses for the previously opened mailbox (which was closed) 4722 and the newly selected mailbox; all responses before the CLOSED 4723 response code relate to the mailbox that was closed, and all 4724 subsequent responses relate to the newly opened mailbox. 4726 There is no need to return the CLOSED response code on 4727 completion of the CLOSE or the UNSELECT command (or similar), 4728 whose purpose is to close the currently selected mailbox 4729 without opening a new one. 4731 CONTACTADMIN 4733 The user should contact the system administrator or support 4734 desk. 4736 C: e login "fred" "foo" 4737 S: e NO [CONTACTADMIN] 4739 COPYUID 4741 Followed by the UIDVALIDITY of the destination mailbox, a UID 4742 set containing the UIDs of the message(s) in the source mailbox 4743 that were copied to the destination mailbox and containing the 4744 UIDs assigned to the copied message(s) in the destination 4745 mailbox, indicates that the message(s) have been copied to the 4746 destination mailbox with the stated UID(s). 4748 The source UID set is in the order the message(s) were copied; 4749 the destination UID set corresponds to the source UID set and 4750 is in the same order. Neither of the UID sets may contain 4751 extraneous UIDs or the symbol "*". 4753 UIDs are assigned in strictly ascending order in the mailbox 4754 (refer to Section 2.3.1.1); note that a range of 12:10 is 4755 exactly equivalent to 10:12 and refers to the sequence 4756 10,11,12. 4758 This response code is returned in a tagged OK response to the 4759 COPY command. 4761 CORRUPTION 4763 The server discovered that some relevant data (e.g., the 4764 mailbox) are corrupt. This response code does not include any 4765 information about what's corrupt, but the server can write that 4766 to its logfiles. 4768 C: i select "/archive/projects/experiment-iv" 4769 S: i NO [CORRUPTION] Cannot open mailbox 4771 EXPIRED 4773 Either authentication succeeded or the server no longer had the 4774 necessary data; either way, access is no longer permitted using 4775 that passphrase. The client or user should get a new 4776 passphrase. 4778 C: d login "fred" "foo" 4779 S: d NO [EXPIRED] That password isn't valid any more 4781 EXPUNGEISSUED 4783 Someone else has issued an EXPUNGE for the same mailbox. The 4784 client may want to issue NOOP soon. [IMAP-MULTIACCESS] 4785 discusses this subject in depth. 4787 C: h search from fred@example.com 4788 S: * ESEARCH (TAG "h") ALL 1:3,5,8,13,21,42 4789 S: h OK [EXPUNGEISSUED] Search completed 4791 HASCHILDREN 4793 The mailbox delete operation failed because the mailbox has one 4794 or more children and the server doesn't allow deletion of 4795 mailboxes with children. 4797 C: m356 DELETE Notes 4798 S: o356 NO [HASCHILDREN] Mailbox "Notes" has children that need 4799 to be deleted first 4801 INUSE 4803 An operation has not been carried out because it involves 4804 sawing off a branch someone else is sitting on. Someone else 4805 may be holding an exclusive lock needed for this operation, or 4806 the operation may involve deleting a resource someone else is 4807 using, typically a mailbox. 4809 The operation may succeed if the client tries again later. 4811 C: g delete "/archive/projects/experiment-iv" 4812 S: g NO [INUSE] Mailbox in use 4814 LIMIT 4816 The operation ran up against an implementation limit of some 4817 kind, such as the number of flags on a single message or the 4818 number of flags used in a mailbox. 4820 C: m STORE 42 FLAGS f1 f2 f3 f4 f5 ... f250 4821 S: m NO [LIMIT] At most 32 flags in one mailbox supported 4823 NONEXISTENT 4825 The operation attempts to delete something that does not exist. 4826 Similar to ALREADYEXISTS. 4828 C: p RENAME this that 4829 S: p NO [NONEXISTENT] No such mailbox 4831 NOPERM 4833 The access control system (e.g., Access Control List (ACL), see 4834 [RFC4314] does not permit this user to carry out an operation, 4835 such as selecting or creating a mailbox. 4837 C: f select "/archive/projects/experiment-iv" 4838 S: f NO [NOPERM] Access denied 4840 OVERQUOTA 4842 The user would be over quota after the operation. (The user 4843 may or may not be over quota already.) 4845 Note that if the server sends OVERQUOTA but doesn't support the 4846 IMAP QUOTA extension defined by [RFC2087], then there is a 4847 quota, but the client cannot find out what the quota is. 4849 C: n1 uid copy 1:* oldmail 4850 S: n1 NO [OVERQUOTA] Sorry 4852 C: n2 uid copy 1:* oldmail 4853 S: n2 OK [OVERQUOTA] You are now over your soft quota 4855 PARSE 4857 The human-readable text represents an error in parsing the 4858 [RFC-5322] header or [MIME-IMB] headers of a message in the 4859 mailbox. 4861 PERMANENTFLAGS 4863 Followed by a parenthesized list of flags, indicates which of 4864 the known flags the client can change permanently. Any flags 4865 that are in the FLAGS untagged response, but not the 4866 PERMANENTFLAGS list, can not be set permanently. The 4867 PERMANENTFLAGS list can also include the special flag \*, which 4868 indicates that it is possible to create new keywords by 4869 attempting to store those keywords in the mailbox. If the 4870 client attempts to STORE a flag that is not in the 4871 PERMANENTFLAGS list, the server will either ignore the change 4872 or store the state change for the remainder of the current 4873 session only. 4875 There is no need for a server that included the special flag \* 4876 to return a new PERMANENTFLAGS response code when a new keyword 4877 was successfully set on a message upon client request. However 4878 if the server has a limit on the number of different keywords 4879 that can be stored in a mailbox and that limit is reached, the 4880 server MUST send a new PERMANENTFLAGS response code without the 4881 special flag \*. 4883 PRIVACYREQUIRED 4885 The operation is not permitted due to a lack of privacy. If 4886 Transport Layer Security (TLS) is not in use, the client could 4887 try STARTTLS (see Section 6.2.1) and then repeat the operation. 4889 C: d login "fred" "foo" 4890 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4892 C: d select inbox 4893 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4895 READ-ONLY 4897 The mailbox is selected read-only, or its access while selected 4898 has changed from read-write to read-only. 4900 READ-WRITE 4902 The mailbox is selected read-write, or its access while 4903 selected has changed from read-only to read-write. 4905 SERVERBUG 4907 The server encountered a bug in itself or violated one of its 4908 own invariants. 4910 C: j select "/archive/projects/experiment-iv" 4911 S: j NO [SERVERBUG] This should not happen 4913 TRYCREATE 4915 An APPEND or COPY attempt is failing because the target mailbox 4916 does not exist (as opposed to some other reason). This is a 4917 hint to the client that the operation can succeed if the 4918 mailbox is first created by the CREATE command. 4920 UIDNEXT 4922 Followed by a decimal number, indicates the next unique 4923 identifier value. Refer to Section 2.3.1.1 for more 4924 information. 4926 UIDNOTSTICKY 4928 The selected mailbox is supported by a mail store that does not 4929 support persistent UIDs; that is, UIDVALIDITY will be different 4930 each time the mailbox is selected. Consequently, APPEND or 4931 COPY to this mailbox will not return an APPENDUID or COPYUID 4932 response code. 4934 This response code is returned in an untagged NO response to 4935 the SELECT command. 4937 Note: servers SHOULD NOT have any UIDNOTSTICKY mail stores. 4938 This facility exists to support legacy mail stores in which 4939 it is technically infeasible to support persistent UIDs. 4940 This should be avoided when designing new mail stores. 4942 UIDVALIDITY 4944 Followed by a decimal number, indicates the unique identifier 4945 validity value. Refer to Section 2.3.1.1 for more information. 4947 UNAVAILABLE 4949 Temporary failure because a subsystem is down. For example, an 4950 IMAP server that uses a Lightweight Directory Access Protocol 4951 (LDAP) or Radius server for authentication might use this 4952 response code when the LDAP/Radius server is down. 4954 C: a LOGIN "fred" "foo" 4955 S: a NO [UNAVAILABLE] User's backend down for maintenance 4957 UNKNOWN-CTE 4959 The server does not know how to decode the section's Content- 4960 Transfer-Encoding. 4962 Client implementations MUST ignore response codes that they do not 4963 recognize. 4965 7.1.1. OK Response 4967 Contents: OPTIONAL response code 4968 human-readable text 4970 The OK response indicates an information message from the server. 4971 When tagged, it indicates successful completion of the associated 4972 command. The human-readable text MAY be presented to the user as an 4973 information message. The untagged form indicates an information-only 4974 message; the nature of the information MAY be indicated by a response 4975 code. 4977 The untagged form is also used as one of three possible greetings at 4978 connection startup. It indicates that the connection is not yet 4979 authenticated and that a LOGIN or an AUTHENTICATE command is needed. 4981 Example: S: * OK IMAP4rev2 server ready 4982 C: A001 LOGIN fred blurdybloop 4983 S: * OK [ALERT] System shutdown in 10 minutes 4984 S: A001 OK LOGIN Completed 4986 7.1.2. NO Response 4988 Contents: OPTIONAL response code 4989 human-readable text 4991 The NO response indicates an operational error message from the 4992 server. When tagged, it indicates unsuccessful completion of the 4993 associated command. The untagged form indicates a warning; the 4994 command can still complete successfully. The human-readable text 4995 describes the condition. 4997 Example: C: A222 COPY 1:2 owatagusiam 4998 S: * NO Disk is 98% full, please delete unnecessary data 4999 S: A222 OK COPY completed 5000 C: A223 COPY 3:200 blurdybloop 5001 S: * NO Disk is 98% full, please delete unnecessary data 5002 S: * NO Disk is 99% full, please delete unnecessary data 5003 S: A223 NO COPY failed: disk is full 5005 7.1.3. BAD Response 5007 Contents: OPTIONAL response code 5008 human-readable text 5010 The BAD response indicates an error message from the server. When 5011 tagged, it reports a protocol-level error in the client's command; 5012 the tag indicates the command that caused the error. The untagged 5013 form indicates a protocol-level error for which the associated 5014 command can not be determined; it can also indicate an internal 5015 server failure. The human-readable text describes the condition. 5017 Example: C: ...very long command line... 5018 S: * BAD Command line too long 5019 C: ...empty line... 5020 S: * BAD Empty command line 5021 C: A443 EXPUNGE 5022 S: * BAD Disk crash, attempting salvage to a new disk! 5023 S: * OK Salvage successful, no data lost 5024 S: A443 OK Expunge completed 5026 7.1.4. PREAUTH Response 5028 Contents: OPTIONAL response code 5029 human-readable text 5031 The PREAUTH response is always untagged, and is one of three possible 5032 greetings at connection startup. It indicates that the connection 5033 has already been authenticated by external means; thus no LOGIN/ 5034 AUTHENTICATE command is needed. 5036 Example: S: * PREAUTH IMAP4rev2 server logged in as Smith 5038 7.1.5. BYE Response 5040 Contents: OPTIONAL response code 5041 human-readable text 5043 The BYE response is always untagged, and indicates that the server is 5044 about to close the connection. The human-readable text MAY be 5045 displayed to the user in a status report by the client. The BYE 5046 response is sent under one of four conditions: 5048 1. as part of a normal logout sequence. The server will close the 5049 connection after sending the tagged OK response to the LOGOUT 5050 command. 5052 2. as a panic shutdown announcement. The server closes the 5053 connection immediately. 5055 3. as an announcement of an inactivity autologout. The server 5056 closes the connection immediately. 5058 4. as one of three possible greetings at connection startup, 5059 indicating that the server is not willing to accept a connection 5060 from this client. The server closes the connection immediately. 5062 The difference between a BYE that occurs as part of a normal LOGOUT 5063 sequence (the first case) and a BYE that occurs because of a failure 5064 (the other three cases) is that the connection closes immediately in 5065 the failure case. In all cases the client SHOULD continue to read 5066 response data from the server until the connection is closed; this 5067 will ensure that any pending untagged or completion responses are 5068 read and processed. 5070 Example: S: * BYE Autologout; idle for too long 5072 7.2. Server Responses - Server and Mailbox Status 5074 These responses are always untagged. This is how server and mailbox 5075 status data are transmitted from the server to the client. Many of 5076 these responses typically result from a command with the same name. 5078 7.2.1. The ENABLED Response 5080 Contents: capability listing 5082 The ENABLED response occurs as a result of an ENABLE command. The 5083 capability listing contains a space-separated listing of capability 5084 names that the server supports and that were successfully enabled. 5086 The ENABLED response may contain no capabilities, which means that no 5087 extensions listed by the client were successfully enabled. 5089 7.2.2. CAPABILITY Response 5091 Contents: capability listing 5093 The CAPABILITY response occurs as a result of a CAPABILITY command. 5094 The capability listing contains a space-separated listing of 5095 capability names that the server supports. The capability listing 5096 MUST include the atom "IMAP4rev2", but note that it doesn't have to 5097 be the first capability listed. 5099 In addition, client and server implementations MUST implement the 5100 "STARTTLS", "LOGINDISABLED", and "AUTH=PLAIN" (described in [PLAIN]) 5101 capabilities. See the Security Considerations (Section 11) for 5102 important information related to these capabilities. 5104 A capability name which begins with "AUTH=" indicates that the server 5105 supports that particular authentication mechanism [SASL]. 5107 The LOGINDISABLED capability indicates that the LOGIN command is 5108 disabled, and that the server will respond with a tagged NO response 5109 to any attempt to use the LOGIN command even if the user name and 5110 password are valid. An IMAP client MUST NOT issue the LOGIN command 5111 if the server advertises the LOGINDISABLED capability. 5113 Other capability names indicate that the server supports an 5114 extension, revision, or amendment to the IMAP4rev2 protocol. Server 5115 responses MUST conform to this document until the client issues a 5116 command that uses the associated capability. 5118 Capability names SHOULD be registered with IANA using RFC Required 5119 policy. A server SHOULD NOT offer unregistered capability names. 5121 Client implementations SHOULD NOT require any capability name other 5122 than "IMAP4rev2", "STARTTLS", "LOGINDISABLED". Client 5123 implementations MUST ignore any unknown capability names. 5125 A server MAY send capabilities automatically, by using the CAPABILITY 5126 response code in the initial PREAUTH or OK responses, and by sending 5127 an updated CAPABILITY response code in the tagged OK response as part 5128 of a successful authentication. It is unnecessary for a client to 5129 send a separate CAPABILITY command if it recognizes these automatic 5130 capabilities. 5132 Example: S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI XPIG-LATIN 5134 7.2.3. LIST Response 5136 Contents: name attributes 5137 hierarchy delimiter 5138 name 5139 OPTIONAL extension data 5141 The LIST response occurs as a result of a LIST command. It returns a 5142 single name that matches the LIST specification. There can be 5143 multiple LIST responses for a single LIST command. 5145 The following base mailbox name attributes are defined: 5147 \NonExistent The "\NonExistent" attribute indicates that a mailbox 5148 name does not refer to an existing mailbox. Note that this 5149 attribute is not meaningful by itself, as mailbox names that match 5150 the canonical LIST pattern but don't exist must not be returned 5151 unless one of the two conditions listed below is also satisfied: 5153 1. The mailbox name also satisfies the selection criteria (for 5154 example, it is subscribed and the "SUBSCRIBED" selection 5155 option has been specified). 5157 2. "RECURSIVEMATCH" has been specified, and the mailbox name has 5158 at least one descendant mailbox name that does not match the 5159 LIST pattern and does match the selection criteria. 5161 In practice, this means that the "\NonExistent" attribute is 5162 usually returned with one or more of "\Subscribed", "\Remote", 5163 "\HasChildren", or the CHILDINFO extended data item. 5165 The "\NonExistent" attribute implies "\NoSelect". 5167 \Noinferiors It is not possible for any child levels of hierarchy to 5168 exist under this name; no child levels exist now and none can be 5169 created in the future. 5171 \Noselect It is not possible to use this name as a selectable 5172 mailbox. 5174 \HasChildren The presence of this attribute indicates that the 5175 mailbox has child mailboxes. A server SHOULD NOT set this 5176 attribute if there are child mailboxes and the user does not have 5177 permission to access any of them. In this case, \HasNoChildren 5178 SHOULD be used. In many cases, however, a server may not be able 5179 to efficiently compute whether a user has access to any child 5180 mailbox. Note that even though the \HasChildren attribute for a 5181 mailbox must be correct at the time of processing of the mailbox, 5182 a client must be prepared to deal with a situation when a mailbox 5183 is marked with the \HasChildren attribute, but no child mailbox 5184 appears in the response to the LIST command. This might happen, 5185 for example, due to children mailboxes being deleted or made 5186 inaccessible to the user (using access control) by another client 5187 before the server is able to list them. 5189 \HasNoChildren The presence of this attribute indicates that the 5190 mailbox has NO child mailboxes that are accessible to the 5191 currently authenticated user. 5193 \Marked The mailbox has been marked "interesting" by the server; the 5194 mailbox probably contains messages that have been added since the 5195 last time the mailbox was selected. 5197 \Unmarked The mailbox does not contain any additional messages since 5198 the last time the mailbox was selected. 5200 \Subscribed The mailbox name was subscribed to using the SUBSCRIBE 5201 command. 5203 \Remote The mailbox is a remote mailbox. 5205 It is an error for the server to return both a \HasChildren and a 5206 \HasNoChildren attribute in the same LIST response. A client that 5207 encounters a LIST response with both \HasChildren and \HasNoChildren 5208 attributes present should act as if both are absent in the LIST 5209 response. 5211 Note: the \HasNoChildren attribute should not be confused with the 5212 \NoInferiors attribute, which indicates that no child mailboxes 5213 exist now and none can be created in the future. 5215 If it is not feasible for the server to determine whether or not the 5216 mailbox is "interesting", the server SHOULD NOT send either \Marked 5217 or \Unmarked. The server MUST NOT send more than one of \Marked, 5218 \Unmarked, and \Noselect for a single mailbox, and MAY send none of 5219 these. 5221 In addition to the base mailbox name attributes defined above, an 5222 IMAP server MAY also include any or all of the following attributes 5223 that denote "role" (or "special-use") of a mailbox. These attributes 5224 are included along with base attributes defined above. A given 5225 mailbox may have none, one, or more than one of these attributes. In 5226 some cases, a special use is advice to a client about what to put in 5227 that mailbox. In other cases, it's advice to a client about what to 5228 expect to find there. 5230 \All This mailbox presents all messages in the user's message store. 5231 Implementations MAY omit some messages, such as, perhaps, those in 5232 \Trash and \Junk. When this special use is supported, it is 5233 almost certain to represent a virtual mailbox. 5235 \Archive This mailbox is used to archive messages. The meaning of 5236 an "archival" mailbox is server-dependent; typically, it will be 5237 used to get messages out of the inbox, or otherwise keep them out 5238 of the user's way, while still making them accessible. 5240 \Drafts This mailbox is used to hold draft messages -- typically, 5241 messages that are being composed but have not yet been sent. In 5242 some server implementations, this might be a virtual mailbox, 5243 containing messages from other mailboxes that are marked with the 5244 "\Draft" message flag. Alternatively, this might just be advice 5245 that a client put drafts here. 5247 \Flagged This mailbox presents all messages marked in some way as 5248 "important". When this special use is supported, it is likely to 5249 represent a virtual mailbox collecting messages (from other 5250 mailboxes) that are marked with the "\Flagged" message flag. 5252 \Junk This mailbox is where messages deemed to be junk mail are 5253 held. Some server implementations might put messages here 5254 automatically. Alternatively, this might just be advice to a 5255 client-side spam filter. 5257 \Sent This mailbox is used to hold copies of messages that have been 5258 sent. Some server implementations might put messages here 5259 automatically. Alternatively, this might just be advice that a 5260 client save sent messages here. 5262 \Trash This mailbox is used to hold messages that have been deleted 5263 or marked for deletion. In some server implementations, this 5264 might be a virtual mailbox, containing messages from other 5265 mailboxes that are marked with the "\Deleted" message flag. 5266 Alternatively, this might just be advice that a client that 5267 chooses not to use the IMAP "\Deleted" model should use this as 5268 its trash location. In server implementations that strictly 5269 expect the IMAP "\Deleted" model, this special use is likely not 5270 to be supported. 5272 All of special-use attributes are OPTIONAL, and any given server or 5273 message store may support any combination of the attributes, or none 5274 at all. In most cases, there will likely be at most one mailbox with 5275 a given attribute for a given user, but in some server or message 5276 store implementations it might be possible for multiple mailboxes to 5277 have the same special-use attribute. 5279 Special-use attributes are likely to be user-specific. User Adam 5280 might share his \Sent mailbox with user Barb, but that mailbox is 5281 unlikely to also serve as Barb's \Sent mailbox. 5283 Other mailbox name attributes can be found in the "IMAP Mailbox Name 5284 Attributes" registry [IMAP-MAILBOX-NAME-ATTRS-REG]. 5286 The hierarchy delimiter is a character used to delimit levels of 5287 hierarchy in a mailbox name. A client can use it to create child 5288 mailboxes, and to search higher or lower levels of naming hierarchy. 5289 All children of a top-level hierarchy node MUST use the same 5290 separator character. A NIL hierarchy delimiter means that no 5291 hierarchy exists; the name is a "flat" name. 5293 The name represents an unambiguous left-to-right hierarchy, and MUST 5294 be valid for use as a reference in LIST command. Unless \Noselect or 5295 \NonExistent is indicated, the name MUST also be valid as an argument 5296 for commands, such as SELECT, that accept mailbox names. 5298 The name might be followed by an OPTIONAL series of extended fields, 5299 a parenthesized list of tagged data (also referred to as "extended 5300 data item"). The first element of an extended field is a string, 5301 which identifies the type of data. [RFC5258] specified requirements 5302 on string registration (which are called "tags" there; such tags are 5303 not to be confused with IMAP command tags), in particular it said 5304 that "Tags MUST be registered with IANA". This document doesn't 5305 change that. See Section 9.5 of [RFC5258] for the registration 5306 template. The server MAY return data in the extended fields that was 5307 not directly solicited by the client in the corresponding LIST 5308 command. For example, the client can enable extra extended fields by 5309 using another IMAP extension that make use of the extended LIST 5310 responses. The client MUST ignore all extended fields it doesn't 5311 recognize. 5313 Example: S: * LIST (\Noselect) "/" ~/Mail/foo 5315 Example: S: * LIST (\Marked) ":" Tables (tablecloth (("edge" "lacy") 5316 ("color" "red")) Sample "text") 5317 S: * LIST () ":" Tables:new (tablecloth ("edge" "lacy") 5318 Sample ("text" "more text")) 5320 7.2.4. NAMESPACE Response 5322 Contents: the prefix and hierarchy delimiter to the server's 5323 Personal Namespace(s), Other Users' Namespace(s), and 5324 Shared Namespace(s) 5326 The NAMESPACE response occurs as a result of a NAMESPACE command. It 5327 contains the prefix and hierarchy delimiter to the server's Personal 5328 Namespace(s), Other Users' Namespace(s), and Shared Namespace(s) that 5329 the server wishes to expose. The response will contain a NIL for any 5330 namespace class that is not available. Namespace-Response-Extensions 5331 ABNF non terminal is defined for extensibility and MAY be included in 5332 the response. 5334 Example: S: * NAMESPACE (("" "/")) (("~" "/")) NIL 5336 7.2.5. STATUS Response 5338 Contents: name 5339 status parenthesized list 5341 The STATUS response occurs as a result of an STATUS command. It 5342 returns the mailbox name that matches the STATUS specification and 5343 the requested mailbox status information. 5345 Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 5347 7.2.6. ESEARCH Response 5349 Contents: one or more search-return-data pairs 5351 The ESEARCH response occurs as a result of a SEARCH or UID SEARCH 5352 command. 5354 The ESEARCH response starts with an optional search correlator. If 5355 it is missing, then the response was not caused by a particular IMAP 5356 command, whereas if it is present, it contains the tag of the command 5357 that caused the response to be returned. 5359 The search correlator is followed by an optional UID indicator. If 5360 this indicator is present, all data in the ESEARCH response refers to 5361 UIDs, otherwise all returned data refers to message numbers. 5363 The rest of the ESEARCH response contains one or more search data 5364 pairs. Each pair starts with unique return item name, followed by a 5365 space and the corresponding data. Search data pairs may be returned 5366 in any order. Unless specified otherwise by an extension, any return 5367 item name SHOULD appear only once in an ESEARCH response. 5369 [[TBD: describe the most common search data pairs returned.]] 5370 Example: S: * ESEARCH UID COUNT 5 ALL 4:19,21,28 5372 Example: S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28 5374 Example: S: * ESEARCH COUNT 5 ALL 1:17,21 5376 7.2.7. FLAGS Response 5378 Contents: flag parenthesized list 5380 The FLAGS response occurs as a result of a SELECT or EXAMINE command. 5381 The flag parenthesized list identifies the flags (at a minimum, the 5382 system-defined flags) that are applicable for this mailbox. Flags 5383 other than the system flags can also exist, depending on server 5384 implementation. 5386 The update from the FLAGS response MUST be recorded by the client. 5388 Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5390 7.3. Server Responses - Mailbox Size 5392 These responses are always untagged. This is how changes in the size 5393 of the mailbox are transmitted from the server to the client. 5394 Immediately following the "*" token is a number that represents a 5395 message count. 5397 7.3.1. EXISTS Response 5399 Contents: none 5401 The EXISTS response reports the number of messages in the mailbox. 5402 This response occurs as a result of a SELECT or EXAMINE command, and 5403 if the size of the mailbox changes (e.g., new messages). 5405 The update from the EXISTS response MUST be recorded by the client. 5407 Example: S: * 23 EXISTS 5409 7.4. Server Responses - Message Status 5411 These responses are always untagged. This is how message data are 5412 transmitted from the server to the client, often as a result of a 5413 command with the same name. Immediately following the "*" token is a 5414 number that represents a message sequence number. 5416 7.4.1. EXPUNGE Response 5418 Contents: none 5420 The EXPUNGE response reports that the specified message sequence 5421 number has been permanently removed from the mailbox. The message 5422 sequence number for each successive message in the mailbox is 5423 immediately decremented by 1, and this decrement is reflected in 5424 message sequence numbers in subsequent responses (including other 5425 untagged EXPUNGE responses). 5427 The EXPUNGE response also decrements the number of messages in the 5428 mailbox; it is not necessary to send an EXISTS response with the new 5429 value. 5431 As a result of the immediate decrement rule, message sequence numbers 5432 that appear in a set of successive EXPUNGE responses depend upon 5433 whether the messages are removed starting from lower numbers to 5434 higher numbers, or from higher numbers to lower numbers. For 5435 example, if the last 5 messages in a 9-message mailbox are expunged, 5436 a "lower to higher" server will send five untagged EXPUNGE responses 5437 for message sequence number 5, whereas a "higher to lower server" 5438 will send successive untagged EXPUNGE responses for message sequence 5439 numbers 9, 8, 7, 6, and 5. 5441 An EXPUNGE response MUST NOT be sent when no command is in progress, 5442 nor while responding to a FETCH, STORE, or SEARCH command. This rule 5443 is necessary to prevent a loss of synchronization of message sequence 5444 numbers between client and server. A command is not "in progress" 5445 until the complete command has been received; in particular, a 5446 command is not "in progress" during the negotiation of command 5447 continuation. 5449 Note: UID FETCH, UID STORE, and UID SEARCH are different commands 5450 from FETCH, STORE, and SEARCH. An EXPUNGE response MAY be sent 5451 during a UID command. 5453 The update from the EXPUNGE response MUST be recorded by the client. 5455 Example: S: * 44 EXPUNGE 5457 7.4.2. FETCH Response 5459 Contents: message data 5461 The FETCH response returns data about a message to the client. The 5462 data are pairs of data item names and their values in parentheses. 5464 This response occurs as the result of a FETCH or STORE command, as 5465 well as by unilateral server decision (e.g., flag updates). 5467 The current data items are: 5469 BINARY[]<> 5471 An or expressing the content of the 5472 specified section after removing any Content-Transfer-Encoding- 5473 related encoding. If is present it refers to the 5474 offset within the DECODED section data. 5476 If the domain of the decoded data is "8bit" and the data does 5477 not contain the NUL octet, the server SHOULD return the data in 5478 a instead of a ; this allows the client to 5479 determine if the "8bit" data contains the NUL octet without 5480 having to explicitly scan the data stream for for NULs. 5482 Messaging clients and servers have been notoriously lax in 5483 their adherence to the Internet CRLF convention for terminating 5484 lines of textual data (text/* media types) in Internet 5485 protocols. When sending data in BINARY[...] FETCH data item, 5486 servers MUST ensure that textual line-oriented sections are 5487 always transmitted using the IMAP4 CRLF line termination 5488 syntax, regardless of the underlying storage representation of 5489 the data on the server. 5491 If the server does not know how to decode the section's 5492 Content-Transfer-Encoding, it MUST fail the request and issue a 5493 "NO" response that contains the "UNKNOWN-CTE" response code. 5495 BINARY.SIZE[] 5497 The size of the section after removing any Content-Transfer- 5498 Encoding-related encoding. The value returned MUST match the 5499 size of the or that will be returned by 5500 the corresponding FETCH BINARY request. 5502 If the server does not know how to decode the section's 5503 Content-Transfer-Encoding, it MUST fail the request and issue a 5504 "NO" response that contains the "UNKNOWN-CTE" response code. 5506 BODY A form of BODYSTRUCTURE without extension data. 5508 BODY[
]<> 5509 A string expressing the body contents of the specified section. 5510 The string SHOULD be interpreted by the client according to the 5511 content transfer encoding, body type, and subtype. 5513 If the origin octet is specified, this string is a substring of 5514 the entire body contents, starting at that origin octet. This 5515 means that BODY[]<0> MAY be truncated, but BODY[] is NEVER 5516 truncated. 5518 Note: The origin octet facility MUST NOT be used by a server 5519 in a FETCH response unless the client specifically requested 5520 it by means of a FETCH of a BODY[
]<> data 5521 item. 5523 8-bit textual data is permitted if a [CHARSET] identifier is 5524 part of the body parameter parenthesized list for this section. 5525 Note that headers (part specifiers HEADER or MIME, or the 5526 header portion of a MESSAGE/RFC822 or MESSAGE/GLOBAL part), MAY 5527 be in UTF-8. Note also that the [RFC-5322] delimiting blank 5528 line between the header and the body is not affected by header 5529 line subsetting; the blank line is always included as part of 5530 header data, except in the case of a message which has no body 5531 and no blank line. 5533 Non-textual data such as binary data MUST be transfer encoded 5534 into a textual form, such as BASE64, prior to being sent to the 5535 client. To derive the original binary data, the client MUST 5536 decode the transfer encoded string. 5538 BODYSTRUCTURE 5540 A parenthesized list that describes the [MIME-IMB] body 5541 structure of a message. This is computed by the server by 5542 parsing the [MIME-IMB] header fields, defaulting various fields 5543 as necessary. 5545 For example, a simple text message of 48 lines and 2279 octets 5546 can have a body structure of: ("TEXT" "PLAIN" ("CHARSET" "US- 5547 ASCII") NIL NIL "7BIT" 2279 48) 5549 Multiple parts are indicated by parenthesis nesting. Instead 5550 of a body type as the first element of the parenthesized list, 5551 there is a sequence of one or more nested body structures. The 5552 second element of the parenthesized list is the multipart 5553 subtype (mixed, digest, parallel, alternative, etc.). 5555 For example, a two part message consisting of a text and a 5556 BASE64-encoded text attachment can have a body structure of: 5558 (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 5559 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") 5560 "<960723163407.20117h@cac.washington.edu>" "Compiler diff" 5561 "BASE64" 4554 73) "MIXED") 5563 Extension data follows the multipart subtype. Extension data 5564 is never returned with the BODY fetch, but can be returned with 5565 a BODYSTRUCTURE fetch. Extension data, if present, MUST be in 5566 the defined order. The extension data of a multipart body part 5567 are in the following order: 5569 body parameter parenthesized list A parenthesized list of 5570 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5571 "bar" is the value of "foo", and "rag" is the value of 5572 "baz"] as defined in [MIME-IMB]. Servers SHOULD decode 5573 parameter value continuations and parameter value character 5574 sets as described in [RFC2231], for example, if the message 5575 contains parameters "baz*0", "baz*1" and "baz*2", the server 5576 should RFC2231-decode them, concatenate and return the 5577 resulting value as a parameter "baz". Similarly, if the 5578 message contains parameters "foo*0*" and "foo*1*", the 5579 server should RFC2231-decode them, convert to UTF-8, 5580 concatenate and return the resulting value as a parameter 5581 "foo*". 5583 body disposition A parenthesized list, consisting of a 5584 disposition type string, followed by a parenthesized list of 5585 disposition attribute/value pairs as defined in 5586 [DISPOSITION]. Servers SHOULD decode parameter value 5587 continuations as described in [RFC2231]. 5589 body language A string or parenthesized list giving the body 5590 language value as defined in [LANGUAGE-TAGS]. 5592 body location A string giving the body content URI as defined 5593 in [LOCATION]. 5595 Any following extension data are not yet defined in this 5596 version of the protocol. Such extension data can consist of 5597 zero or more NILs, strings, numbers, or potentially nested 5598 parenthesized lists of such data. Client implementations that 5599 do a BODYSTRUCTURE fetch MUST be prepared to accept such 5600 extension data. Server implementations MUST NOT send such 5601 extension data until it has been defined by a revision of this 5602 protocol. 5604 The basic fields of a non-multipart body part are in the 5605 following order: 5607 body type A string giving the content media type name as 5608 defined in [MIME-IMB]. 5610 body subtype A string giving the content subtype name as 5611 defined in [MIME-IMB]. 5613 body parameter parenthesized list A parenthesized list of 5614 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5615 "bar" is the value of "foo" and "rag" is the value of "baz"] 5616 as defined in [MIME-IMB]. 5618 body id A string giving the Content-ID header field value as 5619 defined in Section 7 of [MIME-IMB]. 5621 body description A string giving the Content-Description 5622 header field value as defined in Section 8 of [MIME-IMB]. 5624 body encoding A string giving the content transfer encoding as 5625 defined in Section 6 of [MIME-IMB]. 5627 body size A number giving the size of the body in octets. 5628 Note that this size is the size in its transfer encoding and 5629 not the resulting size after any decoding. 5631 A body type of type MESSAGE and subtype RFC822 contains, 5632 immediately after the basic fields, the envelope structure, 5633 body structure, and size in text lines of the encapsulated 5634 message. 5636 A body type of type TEXT contains, immediately after the basic 5637 fields, the size of the body in text lines. Note that this 5638 size is the size in its content transfer encoding and not the 5639 resulting size after any decoding. 5641 Extension data follows the basic fields and the type-specific 5642 fields listed above. Extension data is never returned with the 5643 BODY fetch, but can be returned with a BODYSTRUCTURE fetch. 5644 Extension data, if present, MUST be in the defined order. 5646 The extension data of a non-multipart body part are in the 5647 following order: 5649 body MD5 A string giving the body MD5 value as defined in 5650 [MD5]. 5652 body disposition A parenthesized list with the same content 5653 and function as the body disposition for a multipart body 5654 part. 5656 body language A string or parenthesized list giving the body 5657 language value as defined in [LANGUAGE-TAGS]. 5659 body location A string giving the body content URI as defined 5660 in [LOCATION]. 5662 Any following extension data are not yet defined in this 5663 version of the protocol, and would be as described above under 5664 multipart extension data. 5666 ENVELOPE 5668 A parenthesized list that describes the envelope structure of a 5669 message. This is computed by the server by parsing the 5670 [RFC-5322] header into the component parts, defaulting various 5671 fields as necessary. 5673 The fields of the envelope structure are in the following 5674 order: date, subject, from, sender, reply-to, to, cc, bcc, in- 5675 reply-to, and message-id. The date, subject, in-reply-to, and 5676 message-id fields are strings. The from, sender, reply-to, to, 5677 cc, and bcc fields are parenthesized lists of address 5678 structures. 5680 An address structure is a parenthesized list that describes an 5681 electronic mail address. The fields of an address structure 5682 are in the following order: personal name, [SMTP] at-domain- 5683 list (source route, obs-route), mailbox name, and host name. 5685 [RFC-5322] group syntax is indicated by a special form of 5686 address structure in which the host name field is NIL. If the 5687 mailbox name field is also NIL, this is an end of group marker 5688 (semi-colon in RFC 822 syntax). If the mailbox name field is 5689 non-NIL, this is a start of group marker, and the mailbox name 5690 field holds the group name phrase. 5692 If the Date, Subject, In-Reply-To, and Message-ID header fields 5693 are absent in the [RFC-5322] header, the corresponding member 5694 of the envelope is NIL; if these header fields are present but 5695 empty the corresponding member of the envelope is the empty 5696 string. 5698 Note: some servers may return a NIL envelope member in the 5699 "present but empty" case. Clients SHOULD treat NIL and 5700 empty string as identical. 5702 Note: [RFC-5322] requires that all messages have a valid 5703 Date header field. Therefore, for a well-formed message the 5704 date member in the envelope can not be NIL or the empty 5705 string. However it can be NIL for a malformed or a draft 5706 message. 5708 Note: [RFC-5322] requires that the In-Reply-To and Message- 5709 ID header fields, if present, have non-empty content. 5710 Therefore, for a well-formed message the in-reply-to and 5711 message-id members in the envelope can not be the empty 5712 string. However they can still be the empty string for a 5713 malformed message. 5715 If the From, To, Cc, and Bcc header fields are absent in the 5716 [RFC-5322] header, or are present but empty, the corresponding 5717 member of the envelope is NIL. 5719 If the Sender or Reply-To header fields are absent in the 5720 [RFC-5322] header, or are present but empty, the server sets 5721 the corresponding member of the envelope to be the same value 5722 as the from member (the client is not expected to know to do 5723 this). 5725 Note: [RFC-5322] requires that all messages have a valid 5726 From header field. Therefore, for a well-formed message the 5727 from, sender, and reply-to members in the envelope can not 5728 be NIL. However they can be NIL for a malformed or a draft 5729 message. 5731 FLAGS A parenthesized list of flags that are set for this message. 5733 INTERNALDATE A string representing the internal date of the message. 5735 RFC822.SIZE A number expressing the [RFC-5322] size of the message. 5737 UID A number expressing the unique identifier of the message. 5739 If the server chooses to send unsolicited FETCH responses, they MUST 5740 include UID FETCH item. Note that this is a new requirement when 5741 compared to RFC 3501. 5743 Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827) 5745 7.5. Server Responses - Command Continuation Request 5747 The command continuation request response is indicated by a "+" token 5748 instead of a tag. This form of response indicates that the server is 5749 ready to accept the continuation of a command from the client. The 5750 remainder of this response is a line of text. 5752 This response is used in the AUTHENTICATE command to transmit server 5753 data to the client, and request additional client data. This 5754 response is also used if an argument to any command is a 5755 synchronizing literal. 5757 The client is not permitted to send the octets of the synchronizing 5758 literal unless the server indicates that it is expected. This 5759 permits the server to process commands and reject errors on a line- 5760 by-line basis. The remainder of the command, including the CRLF that 5761 terminates a command, follows the octets of the literal. If there 5762 are any additional command arguments, the literal octets are followed 5763 by a space and those arguments. 5765 Example: C: A001 LOGIN {11} 5766 S: + Ready for additional command text 5767 C: FRED FOOBAR {7} 5768 S: + Ready for additional command text 5769 C: fat man 5770 S: A001 OK LOGIN completed 5771 C: A044 BLURDYBLOOP {102856} 5772 S: A044 BAD No such command as "BLURDYBLOOP" 5774 8. Sample IMAP4rev2 connection 5776 The following is a transcript of an IMAP4rev2 connection. A long 5777 line in this sample is broken for editorial clarity. 5779 S: * OK IMAP4rev2 Service Ready 5780 C: a001 login mrc secret 5781 S: a001 OK LOGIN completed 5782 C: a002 select inbox 5783 S: * 18 EXISTS 5784 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5785 S: * OK [UIDVALIDITY 3857529045] UIDs valid 5786 S: * LIST () "/" INBOX ("OLDNAME" ("inbox")) 5787 S: a002 OK [READ-WRITE] SELECT completed 5788 C: a003 fetch 12 full 5789 S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700" 5790 RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)" 5791 "IMAP4rev2 WG mtg summary and minutes" 5792 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5793 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5794 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5795 ((NIL NIL "imap" "cac.washington.edu")) 5796 ((NIL NIL "minutes" "CNRI.Reston.VA.US") 5797 ("John Klensin" NIL "KLENSIN" "MIT.EDU")) NIL NIL 5798 "") 5799 BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 5800 92)) 5801 S: a003 OK FETCH completed 5802 C: a004 fetch 12 body[header] 5803 S: * 12 FETCH (BODY[HEADER] {342} 5804 S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT) 5805 S: From: Terry Gray 5806 S: Subject: IMAP4rev2 WG mtg summary and minutes 5807 S: To: imap@cac.washington.edu 5808 S: cc: minutes@CNRI.Reston.VA.US, John Klensin 5809 S: Message-Id: 5810 S: MIME-Version: 1.0 5811 S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 5812 S: 5813 S: ) 5814 S: a004 OK FETCH completed 5815 C: a005 store 12 +flags \deleted 5816 S: * 12 FETCH (FLAGS (\Seen \Deleted)) 5817 S: a005 OK +FLAGS completed 5818 C: a006 logout 5819 S: * BYE IMAP4rev2 server terminating connection 5820 S: a006 OK LOGOUT completed 5822 9. Formal Syntax 5824 The following syntax specification uses the Augmented Backus-Naur 5825 Form (ABNF) notation as specified in [ABNF]. 5827 In the case of alternative or optional rules in which a later rule 5828 overlaps an earlier rule, the rule which is listed earlier MUST take 5829 priority. For example, "\Seen" when parsed as a flag is the \Seen 5830 flag name and not a flag-extension, even though "\Seen" can be parsed 5831 as a flag-extension. Some, but not all, instances of this rule are 5832 noted below. 5834 Note: [ABNF] rules MUST be followed strictly; in particular: 5836 (1) Except as noted otherwise, all alphabetic characters are case- 5837 insensitive. The use of upper or lower case characters to define 5838 token strings is for editorial clarity only. Implementations MUST 5839 accept these strings in a case-insensitive fashion. 5841 (2) In all cases, SP refers to exactly one space. It is NOT 5842 permitted to substitute TAB, insert additional spaces, or 5843 otherwise treat SP as being equivalent to LWSP. 5845 (3) The ASCII NUL character, %x00, MUST NOT be used at any time. 5847 address = "(" addr-name SP addr-adl SP addr-mailbox SP 5848 addr-host ")" 5850 addr-adl = nstring 5851 ; Holds route from [RFC-5322] obs-route if 5852 ; non-NIL 5854 addr-host = nstring 5855 ; NIL indicates [RFC-5322] group syntax. 5856 ; Otherwise, holds [RFC-5322] domain name 5858 addr-mailbox = nstring 5859 ; NIL indicates end of [RFC-5322] group; if 5860 ; non-NIL and addr-host is NIL, holds 5861 ; [RFC-5322] group name. 5862 ; Otherwise, holds [RFC-5322] local-part 5863 ; after removing [RFC-5322] quoting 5865 addr-name = nstring 5866 ; If non-NIL, holds phrase from [RFC-5322] 5867 ; mailbox after removing [RFC-5322] quoting 5869 append = "APPEND" SP mailbox [SP flag-list] [SP date-time] SP 5870 literal 5872 append-uid = uniqueid 5874 astring = 1*ASTRING-CHAR / string 5875 ASTRING-CHAR = ATOM-CHAR / resp-specials 5877 atom = 1*ATOM-CHAR 5879 ATOM-CHAR = 5881 atom-specials = "(" / ")" / "{" / SP / CTL / list-wildcards / 5882 quoted-specials / resp-specials 5884 authenticate = "AUTHENTICATE" SP auth-type [SP initial-resp] 5885 *(CRLF base64) 5887 auth-type = atom 5888 ; Defined by [SASL] 5890 base64 = *(4base64-char) [base64-terminal] 5892 base64-char = ALPHA / DIGIT / "+" / "/" 5893 ; Case-sensitive 5895 base64-terminal = (2base64-char "==") / (3base64-char "=") 5897 body = "(" (body-type-1part / body-type-mpart) ")" 5899 body-extension = nstring / number / number64 / 5900 "(" body-extension *(SP body-extension) ")" 5901 ; Future expansion. Client implementations 5902 ; MUST accept body-extension fields. Server 5903 ; implementations MUST NOT generate 5904 ; body-extension fields except as defined by 5905 ; future standard or standards-track 5906 ; revisions of this specification. 5908 body-ext-1part = body-fld-md5 [SP body-fld-dsp [SP body-fld-lang 5909 [SP body-fld-loc *(SP body-extension)]]] 5910 ; MUST NOT be returned on non-extensible 5911 ; "BODY" fetch 5913 body-ext-mpart = body-fld-param [SP body-fld-dsp [SP body-fld-lang 5914 [SP body-fld-loc *(SP body-extension)]]] 5915 ; MUST NOT be returned on non-extensible 5916 ; "BODY" fetch 5918 body-fields = body-fld-param SP body-fld-id SP body-fld-desc SP 5919 body-fld-enc SP body-fld-octets 5921 body-fld-desc = nstring 5922 body-fld-dsp = "(" string SP body-fld-param ")" / nil 5924 body-fld-enc = (DQUOTE ("7BIT" / "8BIT" / "BINARY" / "BASE64"/ 5925 "QUOTED-PRINTABLE") DQUOTE) / string 5926 ; Content-Transfer-Encoding header field value. 5927 ; Defaults to "7BIT" (as per RFC 2045) 5928 ; if not present in the body part. 5930 body-fld-id = nstring 5932 body-fld-lang = nstring / "(" string *(SP string) ")" 5934 body-fld-loc = nstring 5936 body-fld-lines = number64 5938 body-fld-md5 = nstring 5940 body-fld-octets = number 5942 body-fld-param = "(" string SP string *(SP string SP string) ")" / nil 5944 body-type-1part = (body-type-basic / body-type-msg / body-type-text) 5945 [SP body-ext-1part] 5947 body-type-basic = media-basic SP body-fields 5948 ; MESSAGE subtype MUST NOT be "RFC822" or "GLOBAL" 5950 body-type-mpart = 1*body SP media-subtype 5951 [SP body-ext-mpart] 5952 ; MULTIPART body part 5954 body-type-msg = media-message SP body-fields SP envelope 5955 SP body SP body-fld-lines 5957 body-type-text = media-text SP body-fields SP body-fld-lines 5959 capability = ("AUTH=" auth-type) / atom 5960 ; New capabilities MUST begin with "X" or be 5961 ; registered with IANA in 5962 ; a standards-track, an experimental 5963 ; or an informational RFC. 5965 capability-data = "CAPABILITY" *(SP capability) SP "IMAP4rev2" 5966 *(SP capability) 5967 ; Servers MUST implement the STARTTLS, AUTH=PLAIN, 5968 ; and LOGINDISABLED capabilities. 5969 ; Servers which offer RFC 1730 compatibility MUST 5970 ; list "IMAP4" as the first capability. 5971 ; Servers which offer RFC 3501 compatibility MUST 5972 ; list "IMAP4rev1" as one of capabilities. 5974 CHAR = 5976 CHAR8 = %x01-ff 5977 ; any OCTET except NUL, %x00 5979 charset = atom / quoted 5981 childinfo-extended-item = "CHILDINFO" SP "(" 5982 list-select-base-opt-quoted 5983 *(SP list-select-base-opt-quoted) ")" 5984 ; Extended data item (mbox-list-extended-item) 5985 ; returned when the RECURSIVEMATCH 5986 ; selection option is specified. 5987 ; Note 1: the CHILDINFO extended data item tag can be 5988 ; returned with and without surrounding quotes, as per 5989 ; mbox-list-extended-item-tag production. 5990 ; Note 2: The selection options are always returned 5991 ; quoted, unlike their specification in 5992 ; the extended LIST command. 5994 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 5995 ; attributes for CHILDREN return option, at most one 5996 ; possible per LIST response 5998 command = tag SP (command-any / command-auth / command-nonauth / 5999 command-select) CRLF 6000 ; Modal based on state 6002 command-any = "CAPABILITY" / "LOGOUT" / "NOOP" / x-command 6003 ; Valid in all states 6005 command-auth = append / create / delete / enable / examine / list / 6006 Namespace-Command / 6007 rename / select / status / subscribe / unsubscribe / 6008 idle 6009 ; Valid only in Authenticated or Selected state 6011 command-nonauth = login / authenticate / "STARTTLS" 6012 ; Valid only when in Not Authenticated state 6014 command-select = "CLOSE" / "UNSELECT" / "EXPUNGE" / copy / 6015 move / fetch / store / search / uid 6016 ; Valid only when in Selected state 6018 continue-req = "+" SP (resp-text / base64) CRLF 6020 copy = "COPY" SP sequence-set SP mailbox 6022 create = "CREATE" SP mailbox 6023 ; Use of INBOX gives a NO error 6025 date = date-text / DQUOTE date-text DQUOTE 6027 date-day = 1*2DIGIT 6028 ; Day of month 6030 date-day-fixed = (SP DIGIT) / 2DIGIT 6031 ; Fixed-format version of date-day 6033 date-month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / 6034 "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" 6036 date-text = date-day "-" date-month "-" date-year 6038 date-year = 4DIGIT 6040 date-time = DQUOTE date-day-fixed "-" date-month "-" date-year 6041 SP time SP zone DQUOTE 6043 delete = "DELETE" SP mailbox 6044 ; Use of INBOX gives a NO error 6046 digit-nz = %x31-39 6047 ; 1-9 6049 eitem-standard-tag = atom 6050 ; a tag for LIST extended data item defined in a Standard 6051 ; Track or Experimental RFC. 6053 eitem-vendor-tag = vendor-token "-" atom 6054 ; a vendor-specific tag for LIST extended data item 6056 enable = "ENABLE" 1*(SP capability) 6058 enable-data = "ENABLED" *(SP capability) 6060 envelope = "(" env-date SP env-subject SP env-from SP 6061 env-sender SP env-reply-to SP env-to SP env-cc SP 6062 env-bcc SP env-in-reply-to SP env-message-id ")" 6064 env-bcc = "(" 1*address ")" / nil 6065 env-cc = "(" 1*address ")" / nil 6067 env-date = nstring 6069 env-from = "(" 1*address ")" / nil 6071 env-in-reply-to = nstring 6073 env-message-id = nstring 6075 env-reply-to = "(" 1*address ")" / nil 6077 env-sender = "(" 1*address ")" / nil 6079 env-subject = nstring 6081 env-to = "(" 1*address ")" / nil 6083 esearch-response = "ESEARCH" [search-correlator] [SP "UID"] 6084 *(SP search-return-data) 6085 ; ESEARCH response replaces SEARCH response 6086 ; from IMAP4rev1. 6088 examine = "EXAMINE" SP mailbox 6090 fetch = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" / 6091 fetch-att / "(" fetch-att *(SP fetch-att) ")") 6093 fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" / 6094 "RFC822.SIZE" / 6095 "BODY" ["STRUCTURE"] / "UID" / 6096 "BODY" section [partial] / 6097 "BODY.PEEK" section [partial] / 6098 "BINARY" [".PEEK"] section-binary [partial] / 6099 "BINARY.SIZE" section-binary 6101 flag = "\Answered" / "\Flagged" / "\Deleted" / 6102 "\Seen" / "\Draft" / flag-keyword / flag-extension 6103 ; Does not include "\Recent" 6105 flag-extension = "\" atom 6106 ; Future expansion. Client implementations 6107 ; MUST accept flag-extension flags. Server 6108 ; implementations MUST NOT generate 6109 ; flag-extension flags except as defined by 6110 ; future standard or standards-track 6111 ; revisions of this specification. 6112 ; "\Recent" was defined in RFC 3501 6113 ; and is now deprecated. 6115 flag-fetch = flag 6117 flag-keyword = "$MDNSent" / "$Forwarded" / "$Junk" / 6118 "$NotJunk" / "$Phishing" / atom 6120 flag-list = "(" [flag *(SP flag)] ")" 6122 flag-perm = flag / "\*" 6124 greeting = "*" SP (resp-cond-auth / resp-cond-bye) CRLF 6126 header-fld-name = astring 6128 header-list = "(" header-fld-name *(SP header-fld-name) ")" 6130 idle = "IDLE" CRLF "DONE" 6132 initial-resp = (base64 / "=") 6133 ; "initial response" defined in 6134 ; Section 5.1 of [RFC4422] 6136 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 6137 [SP list-return-opts] 6139 list-mailbox = 1*list-char / string 6141 list-char = ATOM-CHAR / list-wildcards / resp-specials 6143 list-return-opts = "RETURN" SP 6144 "(" [return-option *(SP return-option)] ")" 6145 ; list return options, e.g., CHILDREN 6147 list-select-base-opt = "SUBSCRIBED" / option-extension 6148 ; options that can be used by themselves 6150 list-select-base-opt-quoted = DQUOTE list-select-base-opt DQUOTE 6152 list-select-independent-opt = "REMOTE" / option-extension 6153 ; options that do not syntactically interact with 6154 ; other options 6156 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 6157 ; options that require a list-select-base-opt 6158 ; to also be present 6160 list-select-opt = list-select-base-opt / list-select-independent-opt 6161 / list-select-mod-opt 6162 ; An option registration template is described in 6163 ; Section 9.3 of this document. 6165 list-select-opts = "(" [ 6166 (*(list-select-opt SP) list-select-base-opt 6167 *(SP list-select-opt)) 6168 / (list-select-independent-opt 6169 *(SP list-select-independent-opt)) 6170 ] ")" 6171 ; Any number of options may be in any order. 6172 ; If a list-select-mod-opt appears, then a 6173 ; list-select-base-opt must also appear. 6174 ; This allows these: 6175 ; () 6176 ; (REMOTE) 6177 ; (SUBSCRIBED) 6178 ; (SUBSCRIBED REMOTE) 6179 ; (SUBSCRIBED RECURSIVEMATCH) 6180 ; (SUBSCRIBED REMOTE RECURSIVEMATCH) 6181 ; But does NOT allow these: 6182 ; (RECURSIVEMATCH) 6183 ; (REMOTE RECURSIVEMATCH) 6185 list-wildcards = "%" / "*" 6187 literal = "{" number64 ["+"] "}" CRLF *CHAR8 6188 ; represents the number of CHAR8s. 6189 ; A non-synchronizing literal is distinguished from 6190 ; a synchronizing literal by presence of the "+" 6191 ; before the closing "}". 6192 ; Non synchronizing literals are not allowed when 6193 ; sent from server to the client. 6195 literal8 = "~{" number64 "}" CRLF *OCTET 6196 ; represents the number of OCTETs 6197 ; in the response string. 6199 login = "LOGIN" SP userid SP password 6201 mailbox = "INBOX" / astring 6202 ; INBOX is case-insensitive. All case variants of 6203 ; INBOX (e.g., "iNbOx") MUST be interpreted as INBOX 6204 ; not as an astring. An astring which consists of 6205 ; the case-insensitive sequence "I" "N" "B" "O" "X" 6206 ; is considered to be INBOX and not an astring. 6207 ; Refer to section 5.1 for further 6208 ; semantic details of mailbox names. 6210 mailbox-data = "FLAGS" SP flag-list / "LIST" SP mailbox-list / 6211 esearch-response / 6212 "STATUS" SP mailbox SP "(" [status-att-list] ")" / 6213 number SP "EXISTS" / Namespace-Response 6215 mailbox-list = "(" [mbx-list-flags] ")" SP 6216 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 6217 [SP mbox-list-extended] 6218 ; This is the list information pointed to by the ABNF 6219 ; item "mailbox-data", which is defined in [IMAP4] 6221 mbox-list-extended = "(" [mbox-list-extended-item 6222 *(SP mbox-list-extended-item)] ")" 6224 mbox-list-extended-item = mbox-list-extended-item-tag SP 6225 tagged-ext-val 6227 mbox-list-extended-item-tag = astring 6228 ; The content MUST conform to either "eitem-vendor-tag" 6229 ; or "eitem-standard-tag" ABNF productions. 6231 mbox-or-pat = list-mailbox / patterns 6233 mbx-list-flags = *(mbx-list-oflag SP) mbx-list-sflag 6234 *(SP mbx-list-oflag) / 6235 mbx-list-oflag *(SP mbx-list-oflag) 6237 mbx-list-oflag = "\Noinferiors" / child-mbox-flag / 6238 "\Subscribed" / "\Remote" / flag-extension 6239 ; Other flags; multiple possible per LIST response 6241 mbx-list-sflag = "\NonExistent" / "\Noselect" / "\Marked" / "\Unmarked" 6242 ; Selectability flags; only one per LIST response 6244 media-basic = ((DQUOTE ("APPLICATION" / "AUDIO" / "IMAGE" / 6245 "FONT" / "MESSAGE" / "MODEL" / "VIDEO" ) DQUOTE) 6246 / string) 6247 SP media-subtype 6248 ; Defined in [MIME-IMT]. 6249 ; FONT defined in RFC 8081. 6251 media-message = DQUOTE "MESSAGE" DQUOTE SP 6252 DQUOTE ("RFC822" / "GLOBAL") DQUOTE 6253 ; Defined in [MIME-IMT] 6255 media-subtype = string 6256 ; Defined in [MIME-IMT] 6258 media-text = DQUOTE "TEXT" DQUOTE SP media-subtype 6259 ; Defined in [MIME-IMT] 6261 message-data = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att)) 6263 move = "MOVE" SP sequence-set SP mailbox 6265 msg-att = "(" (msg-att-dynamic / msg-att-static) 6266 *(SP (msg-att-dynamic / msg-att-static)) ")" 6268 msg-att-dynamic = "FLAGS" SP "(" [flag-fetch *(SP flag-fetch)] ")" 6269 ; MAY change for a message 6271 msg-att-static = "ENVELOPE" SP envelope / "INTERNALDATE" SP date-time / 6272 "RFC822.SIZE" SP number64 / 6273 "BODY" ["STRUCTURE"] SP body / 6274 "BODY" section ["<" number ">"] SP nstring / 6275 "BINARY" section-binary SP (nstring / literal8) / 6276 "BINARY.SIZE" section-binary SP number / 6277 "UID" SP uniqueid 6278 ; MUST NOT change for a message 6280 name-component = 1*UTF8-CHAR 6281 ; MUST NOT contain ".", "/", "%", or "*" 6283 Namespace = nil / "(" 1*Namespace-Descr ")" 6285 Namespace-Command = "NAMESPACE" 6287 Namespace-Descr = "(" string SP 6288 (DQUOTE QUOTED-CHAR DQUOTE / nil) 6289 [Namespace-Response-Extensions] ")" 6291 Namespace-Response-Extensions = *Namespace-Response-Extension 6293 Namespace-Response-Extension = SP string SP 6294 "(" string *(SP string) ")" 6296 Namespace-Response = "NAMESPACE" SP Namespace 6297 SP Namespace SP Namespace 6298 ; The first Namespace is the Personal Namespace(s). 6299 ; The second Namespace is the Other Users' 6300 ; Namespace(s). 6301 ; The third Namespace is the Shared Namespace(s). 6303 nil = "NIL" 6304 nstring = string / nil 6306 number = 1*DIGIT 6307 ; Unsigned 32-bit integer 6308 ; (0 <= n < 4,294,967,296) 6310 number64 = 1*DIGIT 6311 ; Unsigned 63-bit integer 6312 ; (0 <= n <= 9,223,372,036,854,775,807) 6314 nz-number = digit-nz *DIGIT 6315 ; Non-zero unsigned 32-bit integer 6316 ; (0 < n < 4,294,967,296) 6318 nz-number64 = digit-nz *DIGIT 6319 ; Unsigned 63-bit integer 6320 ; (0 < n <= 9,223,372,036,854,775,807) 6322 oldname-extended-item = "OLDNAME" SP "(" mailbox ")" 6323 ; Extended data item (mbox-list-extended-item) 6324 ; returned in a LIST response when a mailbox is 6325 ; renamed or deleted. Also returned when 6326 ; the server canonicalized the provided mailbox 6327 ; name. 6328 ; Note 1: the OLDNAME tag can be returned 6329 ; with or without surrounding quotes, as per 6330 ; mbox-list-extended-item-tag production. 6332 option-extension = (option-standard-tag / option-vendor-tag) 6333 [SP option-value] 6335 option-standard-tag = atom 6336 ; an option defined in a Standards Track or 6337 ; Experimental RFC 6339 option-val-comp = astring / 6340 option-val-comp *(SP option-val-comp) / 6341 "(" option-val-comp ")" 6343 option-value = "(" option-val-comp ")" 6345 option-vendor-tag = vendor-token "-" atom 6346 ; a vendor-specific option, non-standard 6348 partial-range = number64 ["." nz-number64] 6349 ; Copied from RFC 5092 (IMAP URL) 6350 ; and updated to support 64bit sizes. 6352 partial = "<" number64 "." nz-number64 ">" 6353 ; Partial FETCH request. 0-based offset of 6354 ; the first octet, followed by the number of octets 6355 ; in the fragment. 6357 password = astring 6359 patterns = "(" list-mailbox ")" 6360 ; [RFC5258] supports multiple patterns, 6361 ; but this document only requires one 6362 ; to be supported. 6363 ; If the server is also implementing 6364 ; [RFC5258], "patterns" syntax from that 6365 ; document must be followed. 6367 quoted = DQUOTE *QUOTED-CHAR DQUOTE 6369 QUOTED-CHAR = / 6370 "\" quoted-specials / UTF8-2 / UTF8-3 / UTF8-4 6372 quoted-specials = DQUOTE / "\" 6374 rename = "RENAME" SP mailbox SP mailbox 6375 ; Use of INBOX as a destination gives a NO error 6377 response = *(continue-req / response-data) response-done 6379 response-data = "*" SP (resp-cond-state / resp-cond-bye / 6380 mailbox-data / message-data / capability-data / 6381 enable-data) CRLF 6383 response-done = response-tagged / response-fatal 6385 response-fatal = "*" SP resp-cond-bye CRLF 6386 ; Server closes connection immediately 6388 response-tagged = tag SP resp-cond-state CRLF 6390 resp-code-apnd = "APPENDUID" SP nz-number SP append-uid 6392 resp-code-copy = "COPYUID" SP nz-number SP uid-set SP uid-set 6394 resp-cond-auth = ("OK" / "PREAUTH") SP resp-text 6395 ; Authentication condition 6397 resp-cond-bye = "BYE" SP resp-text 6399 resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text 6400 ; Status condition 6402 resp-specials = "]" 6404 resp-text = ["[" resp-text-code "]" SP] [text] 6406 resp-text-code = "ALERT" / 6407 "BADCHARSET" [SP "(" charset *(SP charset) ")" ] / 6408 capability-data / "PARSE" / 6409 "PERMANENTFLAGS" SP 6410 "(" [flag-perm *(SP flag-perm)] ")" / 6411 "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / 6412 "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number / 6413 resp-code-apnd / resp-code-copy / "UIDNOTSTICKY" / 6414 "UNAVAILABLE" / "AUTHENTICATIONFAILED" / 6415 "AUTHORIZATIONFAILED" / "EXPIRED" / 6416 "PRIVACYREQUIRED" / "CONTACTADMIN" / "NOPERM" / 6417 "INUSE" / "EXPUNGEISSUED" / "CORRUPTION" / 6418 "SERVERBUG" / "CLIENTBUG" / "CANNOT" / 6419 "LIMIT" / "OVERQUOTA" / "ALREADYEXISTS" / 6420 "NONEXISTENT" / "NOTSAVED" / "HASCHILDREN" / 6421 "CLOSED" / 6422 "UNKNOWN-CTE" / 6423 atom [SP 1*] 6425 return-option = "SUBSCRIBED" / "CHILDREN" / status-option / 6426 option-extension 6428 search = "SEARCH" [search-return-opts] 6429 SP search-program 6431 search-correlator = SP "(" "TAG" SP tag-string ")" 6433 search-key = "ALL" / "ANSWERED" / "BCC" SP astring / 6434 "BEFORE" SP date / "BODY" SP astring / 6435 "CC" SP astring / "DELETED" / "FLAGGED" / 6436 "FROM" SP astring / "KEYWORD" SP flag-keyword / 6437 "ON" SP date / "SEEN" / 6438 "SINCE" SP date / "SUBJECT" SP astring / 6439 "TEXT" SP astring / "TO" SP astring / 6440 "UNANSWERED" / "UNDELETED" / "UNFLAGGED" / 6441 "UNKEYWORD" SP flag-keyword / "UNSEEN" / 6442 ; Above this line were in [IMAP2] 6443 "DRAFT" / "HEADER" SP header-fld-name SP astring / 6444 "LARGER" SP number64 / "NOT" SP search-key / 6445 "OR" SP search-key SP search-key / 6446 "SENTBEFORE" SP date / "SENTON" SP date / 6447 "SENTSINCE" SP date / "SMALLER" SP number64 / 6448 "UID" SP sequence-set / "UNDRAFT" / sequence-set / 6449 "(" search-key *(SP search-key) ")" 6451 search-modifier-name = tagged-ext-label 6453 search-mod-params = tagged-ext-val 6454 ; This non-terminal shows recommended syntax 6455 ; for future extensions. 6457 search-program = ["CHARSET" SP charset SP] 6458 search-key *(SP search-key) 6459 ; CHARSET argument to SEARCH MUST be 6460 ; registered with IANA. 6462 search-ret-data-ext = search-modifier-name SP search-return-value 6463 ; Note that not every SEARCH return option 6464 ; is required to have the corresponding 6465 ; ESEARCH return data. 6467 search-return-data = "MIN" SP nz-number / 6468 "MAX" SP nz-number / 6469 "ALL" SP sequence-set / 6470 "COUNT" SP number / 6471 search-ret-data-ext 6472 ; All return data items conform to 6473 ; search-ret-data-ext syntax. 6474 ; Note that "$" marker is not allowed 6475 ; after the ALL return data item. 6477 search-return-opts = SP "RETURN" SP "(" [search-return-opt 6478 *(SP search-return-opt)] ")" 6480 search-return-opt = "MIN" / "MAX" / "ALL" / "COUNT" / 6481 "SAVE" / 6482 search-ret-opt-ext 6483 ; conforms to generic search-ret-opt-ext 6484 ; syntax 6486 search-ret-opt-ext = search-modifier-name [SP search-mod-params] 6488 search-return-value = tagged-ext-val 6489 ; Data for the returned search option. 6490 ; A single "nz-number"/"number"/"number64" value 6491 ; can be returned as an atom (i.e., without 6492 ; quoting). A sequence-set can be returned 6493 ; as an atom as well. 6495 section = "[" [section-spec] "]" 6496 section-binary = "[" [section-part] "]" 6498 section-msgtext = "HEADER" / "HEADER.FIELDS" [".NOT"] SP header-list / 6499 "TEXT" 6500 ; top-level or MESSAGE/RFC822 or MESSAGE/GLOBAL part 6502 section-part = nz-number *("." nz-number) 6503 ; body part reference. 6504 ; Allows for accessing nested body parts. 6506 section-spec = section-msgtext / (section-part ["." section-text]) 6508 section-text = section-msgtext / "MIME" 6509 ; text other than actual body part (headers, etc.) 6511 select = "SELECT" SP mailbox 6513 seq-number = nz-number / "*" 6514 ; message sequence number (COPY, FETCH, STORE 6515 ; commands) or unique identifier (UID COPY, 6516 ; UID FETCH, UID STORE commands). 6517 ; * represents the largest number in use. In 6518 ; the case of message sequence numbers, it is 6519 ; the number of messages in a non-empty mailbox. 6520 ; In the case of unique identifiers, it is the 6521 ; unique identifier of the last message in the 6522 ; mailbox or, if the mailbox is empty, the 6523 ; mailbox's current UIDNEXT value. 6524 ; The server should respond with a tagged BAD 6525 ; response to a command that uses a message 6526 ; sequence number greater than the number of 6527 ; messages in the selected mailbox. This 6528 ; includes "*" if the selected mailbox is empty. 6530 seq-range = seq-number ":" seq-number 6531 ; two seq-number values and all values between 6532 ; these two regardless of order. 6533 ; Example: 2:4 and 4:2 are equivalent and indicate 6534 ; values 2, 3, and 4. 6535 ; Example: a unique identifier sequence range of 6536 ; 3291:* includes the UID of the last message in 6537 ; the mailbox, even if that value is less than 3291. 6539 sequence-set = (seq-number / seq-range) ["," sequence-set] 6540 ; set of seq-number values, regardless of order. 6541 ; Servers MAY coalesce overlaps and/or execute the 6542 ; sequence in any order. 6543 ; Example: a message sequence number set of 6544 ; 2,4:7,9,12:* for a mailbox with 15 messages is 6545 ; equivalent to 2,4,5,6,7,9,12,13,14,15 6546 ; Example: a message sequence number set of *:4,5:7 6547 ; for a mailbox with 10 messages is equivalent to 6548 ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and 6549 ; overlap coalesced to be 4,5,6,7,8,9,10. 6551 sequence-set =/ seq-last-command 6552 ; Allow for "result of the last command" indicator. 6554 seq-last-command = "$" 6556 status = "STATUS" SP mailbox SP 6557 "(" status-att *(SP status-att) ")" 6559 status-att = "MESSAGES" / "UIDNEXT" / "UIDVALIDITY" / 6560 "UNSEEN" / "DELETED" / "SIZE" 6562 status-att-val = ("MESSAGES" SP number) / 6563 ("UIDNEXT" SP nz-number) / 6564 ("UIDVALIDITY" SP nz-number) / 6565 ("UNSEEN" SP number) / 6566 ("DELETED" SP number) / 6567 ("SIZE" SP number64) 6568 ; Extensions to the STATUS responses 6569 ; should extend this production. 6570 ; Extensions should use the generic 6571 ; syntax defined by tagged-ext. 6573 status-att-list = status-att-val *(SP status-att-val) 6575 status-option = "STATUS" SP "(" status-att *(SP status-att) ")" 6576 ; This ABNF production complies with 6577 ; syntax. 6579 store = "STORE" SP sequence-set SP store-att-flags 6581 store-att-flags = (["+" / "-"] "FLAGS" [".SILENT"]) SP 6582 (flag-list / (flag *(SP flag))) 6584 string = quoted / literal 6586 subscribe = "SUBSCRIBE" SP mailbox 6588 tag = 1* 6590 tag-string = astring 6591 ; represented as 6593 tagged-ext-label = tagged-label-fchar *tagged-label-char 6594 ; Is a valid RFC 3501 "atom". 6596 tagged-label-fchar = ALPHA / "-" / "_" / "." 6598 tagged-label-char = tagged-label-fchar / DIGIT / ":" 6600 tagged-ext-comp = astring / 6601 tagged-ext-comp *(SP tagged-ext-comp) / 6602 "(" tagged-ext-comp ")" 6603 ; Extensions that follow this general 6604 ; syntax should use nstring instead of 6605 ; astring when appropriate in the context 6606 ; of the extension. 6607 ; Note that a message set or a "number" 6608 ; can always be represented as an "atom". 6609 ; An URL should be represented as 6610 ; a "quoted" string. 6612 tagged-ext-simple = sequence-set / number / number64 6614 tagged-ext-val = tagged-ext-simple / 6615 "(" [tagged-ext-comp] ")" 6617 text = 1*(TEXT-CHAR / UTF8-2 / UTF8-3 / UTF8-4) 6618 ; Non ASCII text can only be returned 6619 ; after ENABLE IMAP4rev2 command 6621 TEXT-CHAR = 6623 time = 2DIGIT ":" 2DIGIT ":" 2DIGIT 6624 ; Hours minutes seconds 6626 uid = "UID" SP 6627 (copy / move / fetch / search / store / uid-expunge) 6628 ; Unique identifiers used instead of message 6629 ; sequence numbers 6631 uid-expunge = "EXPUNGE" SP sequence-set 6632 ; Unique identifiers used instead of message 6633 ; sequence numbers 6635 uid-set = (uniqueid / uid-range) *("," uid-set) 6637 uid-range = (uniqueid ":" uniqueid) 6638 ; two uniqueid values and all values 6639 ; between these two regards of order. 6640 ; Example: 2:4 and 4:2 are equivalent. 6642 uniqueid = nz-number 6643 ; Strictly ascending 6645 unsubscribe = "UNSUBSCRIBE" SP mailbox 6647 userid = astring 6649 UTF8-2 = 6651 UTF8-3 = 6653 UTF8-4 = 6655 vendor-token = "vendor." name-component 6656 ; Definition copied from RFC 2244. 6657 ; MUST be registered with IANA 6659 x-command = "X" atom 6661 zone = ("+" / "-") 4DIGIT 6662 ; Signed four-digit value of hhmm representing 6663 ; hours and minutes east of Greenwich (that is, 6664 ; the amount that the given time differs from 6665 ; Universal Time). Subtracting the timezone 6666 ; from the given time will give the UT form. 6667 ; The Universal Time zone is "+0000". 6669 10. Author's Note 6671 This document is a revision or rewrite of earlier documents, and 6672 supercedes the protocol specification in those documents: RFC 3501, 6673 RFC 2060, RFC 1730, unpublished IMAP2bis.TXT document, RFC 1176, and 6674 RFC 1064. 6676 11. Security Considerations 6678 IMAP4rev2 protocol transactions, including electronic mail data, are 6679 sent in the clear over the network unless protection from snooping is 6680 negotiated. This can be accomplished either by the use of IMAPS 6681 service, STARTTLS command, negotiated privacy protection in the 6682 AUTHENTICATE command, or some other protection mechanism. 6684 11.1. STARTTLS Security Considerations 6686 IMAP client and server implementations MUST comply with relevant TLS 6687 recommendations from [RFC8314]. 6689 Clients and servers MUST implement TLS 1.2 [TLS-1.2] or newer. Use 6690 of TLS 1.3 [TLS-1.3] is RECOMMENDED. TLS 1.2 may be used only in 6691 cases where the other party has not yet implemented TLS 1.3. 6692 Additionally, when using TLS 1.2, IMAP implementations MUST implement 6693 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite, and SHOULD 6694 implement the TLS_RSA_WITH_AES_128_CBC_SHA [TLS-1.2] cipher suite. 6695 This is important as it assures that any two compliant 6696 implementations can be configured to interoperate. Other TLS cipher 6697 suites recommended in RFC 7525 are RECOMMENDED: 6698 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 6699 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 and 6700 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384. All other cipher suites are 6701 OPTIONAL. Note that this is a change from section 2.1 of [IMAP-TLS]. 6703 The list of mandatory-to-implement TLS 1.3 cipher suites is described 6704 in Section 9.1 of [TLS-1.3]. 6706 During the TLS negotiation [TLS-1.3][TLS-1.2], the client MUST check 6707 its understanding of the server hostname against the server's 6708 identity as presented in the server Certificate message, in order to 6709 prevent man-in-the-middle attacks. This procedure is described in 6710 [RFC7817]. 6712 Both the client and server MUST check the result of the STARTTLS 6713 command and subsequent TLS ([TLS-1.3][TLS-1.2]) negotiation to see 6714 whether acceptable authentication and/or privacy was achieved. 6716 11.2. COPYUID and APPENDUID response codes 6718 The COPYUID and APPENDUID response codes return information about the 6719 mailbox, which may be considered sensitive if the mailbox has 6720 permissions set that permit the client to COPY or APPEND to the 6721 mailbox, but not SELECT or EXAMINE it. 6723 Consequently, these response codes SHOULD NOT be issued if the client 6724 does not have access to SELECT or EXAMINE the mailbox. 6726 11.3. LIST command and Other Users' namespace 6728 In response to a LIST command containing an argument of the Other 6729 Users' Namespace prefix, a server SHOULD NOT list users that have not 6730 granted list access to their personal mailboxes to the currently 6731 authenticated user. Providing such a list, could compromise security 6732 by potentially disclosing confidential information of who is located 6733 on the server, or providing a starting point of a list of user 6734 accounts to attack. 6736 11.4. Other Security Considerations 6738 A server error message for an AUTHENTICATE command which fails due to 6739 invalid credentials SHOULD NOT detail why the credentials are 6740 invalid. 6742 Use of the LOGIN command sends passwords in the clear. This can be 6743 avoided by using the AUTHENTICATE command with a [SASL] mechanism 6744 that does not use plaintext passwords, by first negotiating 6745 encryption via STARTTLS or some other protection mechanism. 6747 A server implementation MUST implement a configuration that, at the 6748 time of authentication, requires: 6749 (1) The STARTTLS command has been negotiated. 6750 OR 6751 (2) Some other mechanism that protects the session from password 6752 snooping has been provided. 6753 OR 6754 (3) The following measures are in place: 6755 (a) The LOGINDISABLED capability is advertised, and [SASL] mechanisms 6756 (such as PLAIN) using plaintext passwords are NOT advertised in the 6757 CAPABILITY list. 6758 AND 6759 (b) The LOGIN command returns an error even if the password is 6760 correct. 6761 AND 6762 (c) The AUTHENTICATE command returns an error with all [SASL] 6763 mechanisms that use plaintext passwords, even if the password is 6764 correct. 6766 A server error message for a failing LOGIN command SHOULD NOT specify 6767 that the user name, as opposed to the password, is invalid. 6769 A server SHOULD have mechanisms in place to limit or delay failed 6770 AUTHENTICATE/LOGIN attempts. 6772 Additional security considerations are discussed in the section 6773 discussing the AUTHENTICATE (see Section 6.2.2) and LOGIN (see 6774 Section 6.2.3) commands. 6776 12. IANA Considerations 6778 IANA is requested to update "Service Names and Transport Protocol 6779 Port Numbers" registry as follows: 6781 1. Registration for TCP port 143 and the corresponding "imap" 6782 service name should be updated to point to this document and RFC 6783 3501. 6785 2. Registration for TCP port 993 and the corresponding "imaps" 6786 service name should be updated to point to this document, RFC 6787 8314 and RFC 3501. 6789 3. Both UDP port 143 and UDP port 993 should be marked as "Reserved" 6790 in the registry. 6792 Additional IANA actions are specified in subsection of this section. 6794 12.1. Updates to IMAP4 Capabilities registry 6796 IMAP4 capabilities are registered by publishing a standards track or 6797 IESG approved informational or experimental RFC. The registry is 6798 currently located at: https://www.iana.org/assignments/ 6799 imap4-capabilities 6801 As this specification revises the AUTH= prefix, STARTTLS and 6802 LOGINDISABLED extensions, IANA is requested to update registry 6803 entries for these 3 extensions to point to this document. 6805 12.2. GSSAPI/SASL service name 6807 GSSAPI/Kerberos/SASL service names are registered by publishing a 6808 standards track or IESG approved experimental RFC. The registry is 6809 currently located at: https://www.iana.org/assignments/gssapi- 6810 service-names 6812 IANA is requested to update the "imap" service name previously 6813 registered in RFC 3501, to point to this document. 6815 12.3. LIST Selection Options, LIST Return Options, LIST extended data 6816 items 6818 [RFC5258] specifies IANA registration procedures for LIST Selection 6819 Options, LIST Return Options, LIST extended data items. This 6820 document doesn't change these registration procedures. In particular 6821 LIST selection options (Section 6.3.9.1) and LIST return options 6822 (Section 6.3.9.2) are registered using the procedure specified in 6823 Section 9 of [RFC5258] (and using the registration template from 6824 Section 9.3 of [RFC5258]). LIST Extended Data Items are registered 6825 using the registration template from Section 9.6 of [RFC5258]). 6827 IANA is requested to add a reference to [RFCXXXX] for the "OLDNAME" 6828 LIST-EXTENDED extended data item entry. This is in addition to the 6829 existing reference to [RFC5465]. 6831 13. References 6833 13.1. Normative References 6835 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access 6836 Protocol version 4 - LIST Command Extensions", RFC 5258, 6837 DOI 10.17487/RFC5258, June 2008, 6838 . 6840 [RFC5788] Melnikov, A. and D. Cridland, "IMAP4 Keyword Registry", 6841 RFC 5788, DOI 10.17487/RFC5788, March 2010, 6842 . 6844 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6845 Specifications: ABNF", STD 68, RFC 5234, January 2008, 6846 . 6848 [ANONYMOUS] 6849 Zeilenga, K., "Anonymous Simple Authentication and 6850 Security Layer (SASL) Mechanism", RFC 4505, June 2006, 6851 . 6853 [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration 6854 Procedures", BCP 19, RFC 2978, October 2000, 6855 . 6857 [SCRAM-SHA-256] 6858 Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple 6859 Authentication and Security Layer (SASL) Mechanisms", 6860 RFC 7677, DOI 10.17487/RFC7677, November 2015, 6861 . 6863 [DISPOSITION] 6864 Troost, R., Dorner, S., and K. Moore, Ed., "Communicating 6865 Presentation Information in Internet Messages: The 6866 Content-Disposition Header Field", RFC 2183, August 1997, 6867 . 6869 [PLAIN] Zeilenga, K., Ed., "The PLAIN Simple Authentication and 6870 Security Layer (SASL) Mechanism", RFC 4616, August 2006, 6871 . 6873 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6874 Requirement Levels", BCP 14, RFC 2119, 6875 DOI 10.17487/RFC2119, March 1997, 6876 . 6878 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 6879 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 6880 May 2017, . 6882 [LANGUAGE-TAGS] 6883 Alvestrand, H., "Content Language Headers", RFC 3282, May 6884 2002, . 6886 [LOCATION] 6887 Palme, J., Hopmann, A., and N. Shelness, "MIME 6888 Encapsulation of Aggregate Documents, such as HTML 6889 (MHTML)", RFC 2557, March 1999, 6890 . 6892 [MD5] Myers, J. and M. Rose, "The Content-MD5 Header Field", 6893 RFC 1864, October 1995, 6894 . 6896 [MIME-HDRS] 6897 Moore, K., "MIME (Multipurpose Internet Mail Extensions) 6898 Part Three: Message Header Extensions for Non-ASCII Text", 6899 RFC 2047, November 1996, 6900 . 6902 [MIME-IMB] 6903 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6904 Extensions (MIME) Part One: Format of Internet Message 6905 Bodies", RFC 2045, November 1996, 6906 . 6908 [MIME-IMT] 6909 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6910 Extensions (MIME) Part Two: Media Types", RFC 2046, 6911 November 1996, . 6913 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 6914 Word Extensions: Character Sets, Languages, and 6915 Continuations", RFC 2231, DOI 10.17487/RFC2231, November 6916 1997, . 6918 [RFC-5322] 6919 Resnick, P., Ed., "Internet Message Format", RFC 5322, 6920 October 2008, . 6922 [SASL] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 6923 Authentication and Security Layer (SASL)", RFC 4422, June 6924 2006, . 6926 [TLS-1.2] Dierks, T. and E. Rescorla, "The Transport Layer Security 6927 (TLS) Protocol Version 1.2", RFC 5246, August 2008, 6928 . 6930 [TLS-1.3] Rescorla, E., "The Transport Layer Security (TLS) Protocol 6931 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 6932 . 6934 [UTF-7] Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe 6935 Transformation Format of Unicode", RFC 2152, May 1997, 6936 . 6938 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 6939 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 6940 2003, . 6942 [MULTIAPPEND] 6943 Crispin, M., "Internet Message Access Protocol (IMAP) - 6944 MULTIAPPEND Extension", RFC 3502, March 2003, 6945 . 6947 [NET-UNICODE] 6948 Klensin, J. and M. Padlipsky, "Unicode Format for Network 6949 Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008, 6950 . 6952 [I18N-HDRS] 6953 Yang, A., Steele, S., and N. Freed, "Internationalized 6954 Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 6955 2012, . 6957 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 6958 Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, 6959 . 6961 [RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS) 6962 Server Identity Check Procedure for Email-Related 6963 Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016, 6964 . 6966 [RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition 6967 Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, 6968 February 2017, . 6970 [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: 6971 Use of Transport Layer Security (TLS) for Email Submission 6972 and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, 6973 . 6975 [IMAP-IMPLEMENTATION] 6976 Leiba, B., "IMAP4 Implementation Recommendations", 6977 RFC 2683, September 1999, 6978 . 6980 [IMAP-MULTIACCESS] 6981 Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", 6982 RFC 2180, July 1997, 6983 . 6985 13.2. Informative References (related protocols) 6987 [RFC3503] Melnikov, A., "Message Disposition Notification (MDN) 6988 profile for Internet Message Access Protocol (IMAP)", 6989 RFC 3503, DOI 10.17487/RFC3503, March 2003, 6990 . 6992 [RFC5256] Crispin, M. and K. Murchison, "Internet Message Access 6993 Protocol - SORT and THREAD Extensions", RFC 5256, 6994 DOI 10.17487/RFC5256, June 2008, 6995 . 6997 [RFC2193] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 6998 DOI 10.17487/RFC2193, September 1997, 6999 . 7001 [RFC3348] Gahrns, M. and R. Cheng, "The Internet Message Action 7002 Protocol (IMAP4) Child Mailbox Extension", RFC 3348, 7003 DOI 10.17487/RFC3348, July 2002, 7004 . 7006 [RFC5465] Gulbrandsen, A., King, C., and A. Melnikov, "The IMAP 7007 NOTIFY Extension", RFC 5465, DOI 10.17487/RFC5465, 7008 February 2009, . 7010 [RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals", 7011 RFC 7888, DOI 10.17487/RFC7888, May 2016, 7012 . 7014 [IMAP-DISC] 7015 Melnikov, A., Ed., "Synchronization Operations for 7016 Disconnected IMAP4 Clients", RFC 4549, June 2006, 7017 . 7019 [IMAP-I18N] 7020 Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 7021 Message Access Protocol Internationalization", RFC 5255, 7022 DOI 10.17487/RFC5255, June 2008, 7023 . 7025 [IMAP-MODEL] 7026 Crispin, M., "Distributed Electronic Mail Models in 7027 IMAP4", RFC 1733, December 1994, 7028 . 7030 [IMAP-UTF-8] 7031 Resnick, P., Ed., Newman, C., Ed., and S. Shen, Ed., "IMAP 7032 Support for UTF-8", RFC 6855, DOI 10.17487/RFC6855, March 7033 2013, . 7035 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 7036 October 2008, . 7038 [RFC3516] Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516, 7039 DOI 10.17487/RFC3516, April 2003, 7040 . 7042 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 7043 RFC 4314, December 2005, 7044 . 7046 [RFC2087] Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 7047 1997, . 7049 [IMAP-URL] 7050 Melnikov, A., Ed. and C. Newman, "IMAP URL Scheme", 7051 RFC 5092, DOI 10.17487/RFC5092, November 2007, 7052 . 7054 [IMAP-KEYWORDS-REG] 7055 IANA, "IMAP and JMAP Keywords", December 2009, 7056 . 7059 [IMAP-MAILBOX-NAME-ATTRS-REG] 7060 IANA, "IMAP Mailbox Name Attributes", June 2018, 7061 . 7064 [CHARSET-REG] 7065 IANA, "Character Set Registrations", May 2015, 7066 . 7069 13.3. Informative References (historical aspects of IMAP and related 7070 protocols) 7072 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 7073 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003, 7074 . 7076 [IMAP-COMPAT] 7077 Crispin, M., "IMAP4 Compatibility with IMAP2bis", 7078 RFC 2061, December 1996, 7079 . 7081 [IMAP-HISTORICAL] 7082 Crispin, M., "IMAP4 Compatibility with IMAP2 and 7083 IMAP2bis", RFC 1732, December 1994, 7084 . 7086 [IMAP-OBSOLETE] 7087 Crispin, M., "Internet Message Access Protocol - Obsolete 7088 Syntax", RFC 2062, December 1996, 7089 . 7091 [IMAP2] Crispin, M., "Interactive Mail Access Protocol: Version 7092 2", RFC 1176, August 1990, 7093 . 7095 [RFC-822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET 7096 TEXT MESSAGES", STD 11, RFC 822, August 1982, 7097 . 7099 [IMAP-TLS] 7100 Newman, C., "Using TLS with IMAP, POP3 and ACAP", 7101 RFC 2595, June 1999, 7102 . 7104 Appendix A. Backward compatibility with IMAP4rev1 7106 An implementation that wants to remain compatible with IMAP4rev1 can 7107 advertise both IMAP4rev1 and IMAP4rev2 in its CAPABILITY response/ 7108 response code. While some IMAP4rev1 responses were removed in 7109 IMAP4rev2, their presence will not break IMAP4rev2-only clients. 7111 If both IMAP4rev1 and IMAP4rev2 are advertised, an IMAP client that 7112 wants to use IMAP4rev2 MUST issue an "ENABLE IMAP4rev2" command. 7114 Servers advertising both IMAP4rev1 and IMAP4rev2 MUST NOT generate 7115 UTF-8 quoted strings unless the client has issued "ENABLE IMAP4rev2". 7116 Consider implementation of mechanisms described or referenced in 7117 [IMAP-UTF-8] to achieve this goal. 7119 Servers advertising both IMAP4rev1 and IMAP4rev2, and clients 7120 intending to be compatible with IMAP4rev1 servers MUST be compatible 7121 with the international mailbox naming convention described in the 7122 following subsection. 7124 Also see Appendix D for special considerations for servers that 7125 support 63 bit body part/message sizes and want to advertise support 7126 for both IMAP4rev1 and IMAP4rev2. 7128 A.1. Mailbox International Naming Convention for compatibility with 7129 IMAP4rev1 7131 Support for the Mailbox International Naming Convention described in 7132 this section is not required for IMAP4rev2-only clients and servers. 7133 It is only used for backward compatibility with IMAP4rev1 7134 implementations. 7136 By convention, international mailbox names in IMAP4rev1 are specified 7137 using a modified version of the UTF-7 encoding described in [UTF-7]. 7138 Modified UTF-7 may also be usable in servers that implement an 7139 earlier version of this protocol. 7141 In modified UTF-7, printable US-ASCII characters, except for "&", 7142 represent themselves; that is, characters with octet values 0x20-0x25 7143 and 0x27-0x7e. The character "&" (0x26) is represented by the two- 7144 octet sequence "&-". 7146 All other characters (octet values 0x00-0x1f and 0x7f-0xff) are 7147 represented in modified BASE64, with a further modification from 7148 [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be 7149 used to represent any printing US-ASCII character which can represent 7150 itself. Only characters inside the modified BASE64 alphabet are 7151 permitted in modified BASE64 text. 7153 "&" is used to shift to modified BASE64 and "-" to shift back to US- 7154 ASCII. There is no implicit shift from BASE64 to US-ASCII, and null 7155 shifts ("-&" while in BASE64; note that "&-" while in US-ASCII means 7156 "&") are not permitted. However, all names start in US-ASCII, and 7157 MUST end in US-ASCII; that is, a name that ends with a non-ASCII 7158 ISO-10646 character MUST end with a "-"). 7160 The purpose of these modifications is to correct the following 7161 problems with UTF-7: 7163 1. UTF-7 uses the "+" character for shifting; this conflicts with 7164 the common use of "+" in mailbox names, in particular USENET 7165 newsgroup names. 7167 2. UTF-7's encoding is BASE64 which uses the "/" character; this 7168 conflicts with the use of "/" as a popular hierarchy delimiter. 7170 3. UTF-7 prohibits the unencoded usage of "\"; this conflicts with 7171 the use of "\" as a popular hierarchy delimiter. 7173 4. UTF-7 prohibits the unencoded usage of "~"; this conflicts with 7174 the use of "~" in some servers as a home directory indicator. 7176 5. UTF-7 permits multiple alternate forms to represent the same 7177 string; in particular, printable US-ASCII characters can be 7178 represented in encoded form. 7180 Although modified UTF-7 is a convention, it establishes certain 7181 requirements on server handling of any mailbox name with an embedded 7182 "&" character. In particular, server implementations MUST preserve 7183 the exact form of the modified BASE64 portion of a modified UTF-7 7184 name and treat that text as case-sensitive, even if names are 7185 otherwise case-insensitive or case-folded. 7187 Server implementations SHOULD verify that any mailbox name with an 7188 embedded "&" character, used as an argument to CREATE, is: in the 7189 correctly modified UTF-7 syntax, has no superfluous shifts, and has 7190 no encoding in modified BASE64 of any printing US-ASCII character 7191 which can represent itself. However, client implementations MUST NOT 7192 depend upon the server doing this, and SHOULD NOT attempt to create a 7193 mailbox name with an embedded "&" character unless it complies with 7194 the modified UTF-7 syntax. 7196 Server implementations which export a mail store that does not follow 7197 the modified UTF-7 convention MUST convert to modified UTF-7 any 7198 mailbox name that contains either non-ASCII characters or the "&" 7199 character. 7201 For example, here is a mailbox name which mixes English, Chinese, 7202 and Japanese text: ~peter/mail/&U,BTFw-/&ZeVnLIqe- 7204 For example, the string "&Jjo!" is not a valid mailbox name 7205 because it does not contain a shift to US-ASCII before the "!". 7206 The correct form is "&Jjo-!". The string "&U,BTFw-&ZeVnLIqe-" is 7207 not permitted because it contains a superfluous shift. The 7208 correct form is "&U,BTF2XlZyyKng-". 7210 Appendix B. Backward compatibility with BINARY extension 7212 IMAP4rev2 incorporates subset of functionality provided by the BINARY 7213 extension [RFC3516], in particular it includes additional FETCH items 7214 (BINARY, BINARY.PEEK and BINARY.SIZE), but not extensions to the 7215 APPEND command. IMAP4rev2 implementations that supports full RFC 7216 3516 functionality need to also advertise the BINARY capability in 7217 the CAPABILITY response/response code. 7219 Appendix C. Backward compatibility with LIST-EXTENDED extension 7221 IMAP4rev2 incorporates most of functionality provided by the LIST- 7222 EXTENDED extension [RFC5258]. In particular, multiple mailbox 7223 patterns syntax is not supported in IMAP4rev2, unless LIST-EXTENDED 7224 capability is also advertised in the CAPABILITY response/response 7225 code. 7227 Appendix D. 63 bit body part and message sizes 7229 IMAP4rev2 increases allowed body part and message sizes that servers 7230 can support from 32 to 63 bits. Server implementations don't have to 7231 support 63 bit long body parts/message sizes, however client 7232 implementations have to expect them. 7234 As IMAP4rev1 didn't support 63 bit long body part/message sizes, 7235 there is an interoperability issue exposed by 63 bit capable servers 7236 that are accessible by both IMAP4rev1 and IMAP4rev2 email clients. 7237 As IMAP4rev1 would be unable to retrieve full content of messages 7238 bigger than 4Gb, such servers either need to replace messages bigger 7239 that 4Gb with messages under 4Gb or hide them from IMAP4rev1 clients. 7240 This document doesn't prescribe any implementation strategy to 7241 address this issue. 7243 Appendix E. Changes from RFC 3501 / IMAP4rev1 7245 Below is the summary of changes since RFC 3501: 7247 1. Support for 64bit message and body part sizes. 7249 2. Folded in IMAP NAMESPACE (RFC 2342), UNSELECT (RFC 3691), 7250 UIDPLUS (RFC 4315), ESEARCH (RFC 4731), SEARCHRES (RFC 5182), 7251 ENABLE (RFC 5161), IDLE (RFC 2177), SASL-IR (RFC 4959), LIST- 7252 EXTENDED (RFC 5258), LIST-STATUS (RFC 5819), MOVE (RFC 6851) and 7253 LITERAL- (RFC 7888) extensions. Also folded RFC 4466 (IMAP ABNF 7254 extensions), RFC 5530 (response codes), the FETCH side of the 7255 BINARY extension (RFC 3516) and the list of new mailbox 7256 attributes from SPECIAL-USE (RFC 6154). 7258 3. Added STATUS SIZE (RFC 8438) and STATUS DELETED. 7260 4. SEARCH command now requires to return ESEARCH response (SEARCH 7261 response is now deprecated). 7263 5. Clarified which SEARCH keys has to use substring match and which 7264 don't. 7266 6. Clarified that server should decode parameter value 7267 continuations as described in [RFC2231]. This requirement was 7268 hidden in RFC 2231 itself. 7270 7. Added CLOSED response code from RFC 7162. SELECT/EXAMINE when a 7271 mailbox is already selected now require for the CLOSED response 7272 code to be returned. 7274 8. SELECT/EXAMINE are now required to return untagged LIST 7275 response. 7277 9. UNSEEN response code on SELECT/EXAMINE is now deprecated. 7279 10. RECENT response on SELECT/EXAMINE, \Recent flag, RECENT STATUS, 7280 SEARCH NEW items are now deprecated. 7282 11. Clarified that the server doesn't need to send a new 7283 PERMANENTFLAGS response code when a new keyword was successfully 7284 added and the server advertised \* earlier for the same mailbox. 7286 12. For future extensibility extended ABNF for tagged-ext-simple to 7287 allow for bare number64. 7289 13. Added SHOULD level requirement on IMAP servers to support 7290 $MDNSent, $Forwarded, $Junk, $NonJunk and $Phishing keywords. 7292 14. Mailbox names and message headers now allow for UTF-8. Support 7293 for Modified UTF-7 in mailbox names is not required, unless 7294 compatibility with IMAP4rev1 is desired. 7296 15. Removed the CHECK command. Clients should use NOOP instead. 7298 16. RFC822, RFC822.HEADER and RFC822.TEXT FETCH data items were 7299 deprecated. Clients should use the corresponding BODY[] 7300 variants instead. 7302 17. LSUB command was deprecated. Clients should use LIST 7303 (SUBSCRIBED) instead. 7305 18. IDLE command can now return updates not related to the currently 7306 selected mailbox state. 7308 19. All unsolicited FETCH updates are required to include UID. 7310 20. Clarified that client implementations MUST ignore response codes 7311 that they do not recognize. (Change from a SHOULD to a MUST.) 7313 21. resp-text ABNF non terminal was updated to allow for empty text. 7315 22. After ENABLE IMAP4rev2 human readable response text can include 7316 non ASCII encoded in UTF-8. 7318 23. Updated to use modern TLS-related recommendations as per RFC 7319 8314, RFC 7817, RFC 7525. 7321 24. Replaced DIGEST-MD5 SASL mechanism with SCRAM-SHA-256. DIGEST- 7322 MD5 was deprecated. 7324 25. Clarified that any command received from the client resets 7325 server autologout timer. 7327 26. Revised IANA registration procedure for IMAP extensions and 7328 removed "X" convention. 7330 Appendix F. Other Recommended IMAP Extensions 7332 Support for the following extensions is recommended for all IMAP 7333 client and servers. Why they significantly reduce bandwidth and/or 7334 number of round trips used by IMAP in certain situations, the EXTRA 7335 WG decided that requiring them as a part of IMAP4rev2 would push the 7336 bar to implement too high for new implementations. Also note that 7337 absence of any IMAP extension from this list doesn't make it somehow 7338 deficient or not recommended for use with IMAP4rev2. 7340 1. QRESYNC and CONDSTORE extensions (RFC 7162). They make 7341 discovering changes to IMAP mailboxes more efficient, at the 7342 expense of storing a bit more state. 7344 2. OBJECTID extension (RFC 8474) helps with preserving IMAP client 7345 cache when messages moved/copied or mailboxes are renamed. 7347 Appendix G. Acknowledgement 7349 Earlier versions of this document were edited by Mark Crispin. 7350 Sadly, he is no longer available to help with this work. Editors of 7351 this revisions are hoping that Mark would have approved. 7353 Chris Newman has contributed text on I18N and use of UTF-8 in 7354 messages and mailbox names. 7356 Thank you to Tony Hansen for helping with the index generation. 7357 Thank you to Murray Kucherawy, Timo Sirainen, Bron Gondwana, Stephan 7358 Bosch and Arnt Gulbrandsen for extensive feedback. 7360 This document incorporate text from RFC 4315 (by Mark Crispin), RFC 7361 4466 (by Cyrus Daboo), RFC 4731 (by Dave Cridland), RFC 5161 (by Arnt 7362 Gulbrandsen), RFC 5465 (by Arnt Gulbrandsen and Curtis King), RFC 7363 5530 (by Arnt Gulbrandsen), RFC 5819 (by Timo Sirainen), RFC 6154 (by 7364 Jamie Nicolson), RFC 8438 (by Stephan Bosch) so work done by authors/ 7365 editors of these documents is appreciated. Note that editors of this 7366 document were redacted from the above list. 7368 The CHILDREN return option was originally proposed by Mike Gahrns and 7369 Raymond Cheng in [RFC3348]. Most of the information in 7370 Section 6.3.9.5 is taken directly from their original specification 7371 [RFC3348]. 7373 Thank you to Damian Poddebniak for pointing out that the ENABLE 7374 command should be a member of "command-auth" and not "command-any" 7375 ABNF production. 7377 Index 7379 $ 7380 $Forwarded (predefined flag) 12 7381 $Junk (predefined flag) 12 7382 $MDNSent (predefined flag) 12 7383 $NotJunk (predefined flag) 13 7384 $Phishing (predefined flag) 13 7386 + 7387 +FLAGS 92 7388 +FLAGS.SILENT 92 7390 - 7391 -FLAGS 92 7392 -FLAGS.SILENT 92 7394 A 7395 ALERT (response code) 99 7396 ALL (fetch item) 88 7397 ALL (search key) 78 7398 ALL (search result option) 76 7399 ALREADYEXISTS (response code) 99 7400 ANSWERED (search key) 78 7401 APPEND (command) 68 7402 APPENDUID (response code) 100 7403 AUTHENTICATE (command) 29 7404 AUTHENTICATIONFAILED (response code) 100 7405 AUTHORIZATIONFAILED (response code) 100 7407 B 7408 BAD (response) 108 7409 BADCHARSET (response code) 101 7410 BCC (search key) 78 7411 BEFORE (search key) 78 7412 BINARY.PEEK[]<> (fetch item) 88 7413 BINARY.SIZE[] (fetch item) 89 7414 BINARY.SIZE[] (fetch result) 118 7415 BINARY[]<> (fetch result) 118 7416 BINARY[]<> (fetch item) 88 7417 BODY (fetch item) 89 7418 BODY (fetch result) 118 7419 BODY (search key) 78 7420 BODY.PEEK[
]<> (fetch item) 89 7421 BODYSTRUCTURE (fetch item) 90 7422 BODYSTRUCTURE (fetch result) 119 7423 BODY[
]<> (fetch result) 118 7424 BODY[
]<> (fetch item) 89 7425 BYE (response) 109 7426 Body Structure (message attribute) 14 7428 C 7429 CANNOT (response code) 101 7430 CAPABILITY (command) 26 7431 CAPABILITY (response code) 101 7432 CAPABILITY (response) 110 7433 CC (search key) 78 7434 CLIENTBUG (response code) 101 7435 CLOSE (command) 74 7436 CLOSED (response code) 102 7437 CONTACTADMIN (response code) 102 7438 COPY (command) 93 7439 COPYUID (response code) 102 7440 CORRUPTION (response code) 103 7441 COUNT (search result option) 76 7442 CREATE (command) 38 7444 D 7445 DELETE (command) 40 7446 DELETED (search key) 78 7447 DELETED (status item) 68 7448 DRAFT (search key) 78 7450 E 7451 ENABLE (command) 33 7452 ENVELOPE (fetch item) 90 7453 ENVELOPE (fetch result) 122 7454 ESEARCH (response) 115 7455 EXAMINE (command) 37 7456 EXPIRED (response code) 103 7457 EXPUNGE (command) 75 7458 EXPUNGE (response) 117 7459 EXPUNGEISSUED (response code) 103 7460 Envelope Structure (message attribute) 14 7462 F 7463 FAST (fetch item) 88 7464 FETCH (command) 87 7465 FETCH (response) 117 7466 FLAGGED (search key) 78 7467 FLAGS (fetch item) 90 7468 FLAGS (fetch result) 123 7469 FLAGS (response) 116 7470 FLAGS (store command data item) 92 7471 FLAGS.SILENT (store command data item) 92 7472 FROM (search key) 78 7473 FULL (fetch item) 88 7474 Flags (message attribute) 11 7476 H 7477 HASCHILDREN (response code) 103 7478 HEADER (part specifier) 90 7479 HEADER (search key) 79 7480 HEADER.FIELDS (part specifier) 90 7481 HEADER.FIELDS.NOT (part specifier) 90 7483 I 7484 IDLE (command) 71 7485 INTERNALDATE (fetch item) 90 7486 INTERNALDATE (fetch result) 123 7487 INUSE (response code) 103 7488 Internal Date (message attribute) 13 7490 K 7491 KEYWORD (search key) 79 7492 Keyword (type of flag) 12 7494 L 7495 LARGER (search key) 79 7496 LIMIT (response code) 104 7497 LIST (command) 45 7498 LIST (response) 111 7499 LOGOUT (command) 27 7501 M 7502 MAX (search result option) 76 7503 MAY (specification requirement term) 5 7504 MESSAGES (status item) 68 7505 MIME (part specifier) 91 7506 MIN (search result option) 76 7507 MOVE (command) 94 7508 MUST (specification requirement term) 5 7509 MUST NOT (specification requirement term) 5 7510 Message Sequence Number (message attribute) 11 7512 N 7513 NAMESPACE (command) 63 7514 NAMESPACE (response) 114 7515 NO (response) 107 7516 NONEXISTENT (response code) 104 7517 NOOP (command) 27 7518 NOPERM (response code) 104 7519 NOT (search key) 79 7520 NOT RECOMMENDED (specification requirement term) 5 7522 O 7523 OK (response) 107 7524 ON (search key) 79 7525 OPTIONAL (specification requirement term) 5 7526 OR (search key) 79 7527 OVERQUOTA (response code) 104 7529 P 7530 PARSE (response code) 105 7531 PERMANENTFLAGS (response code) 105 7532 PREAUTH (response) 108 7533 PRIVACYREQUIRED (response code) 105 7534 Permanent Flag (class of flag) 13 7535 Predefined keywords 12 7537 R 7538 READ-ONLY (response code) 105 7539 READ-WRITE (response code) 106 7540 RECOMMENDED (specification requirement term) 5 7541 RENAME (command) 41 7542 REQUIRED (specification requirement term) 5 7543 RFC822.SIZE (fetch item) 90 7544 RFC822.SIZE (fetch result) 123 7546 S 7547 SAVE (search result option) 76 7548 SEARCH (command) 75 7549 SEEN (search key) 79 7550 SELECT (command) 35 7551 SENTBEFORE (search key) 79 7552 SENTON (search key) 79 7553 SENTSINCE (search key) 79 7554 SERVERBUG (response code) 106 7555 SHOULD (specification requirement term) 5 7556 SHOULD NOT (specification requirement term) 5 7557 SINCE (search key) 79 7558 SIZE (status item) 68 7559 SMALLER (search key) 79 7560 STARTTLS (command) 28 7561 STATUS (command) 67 7562 STATUS (response) 115 7563 STORE (command) 92 7564 SUBJECT (search key) 79 7565 SUBSCRIBE (command) 44 7566 Session Flag (class of flag) 13 7567 System Flag (type of flag) 12 7569 T 7570 TEXT (part specifier) 90 7571 TEXT (search key) 80 7572 TO (search key) 80 7573 TRYCREATE (response code) 106 7575 U 7576 UID (command) 96 7577 UID (fetch item) 90 7578 UID (fetch result) 123 7579 UID (search key) 80 7580 UIDNEXT (response code) 106 7581 UIDNEXT (status item) 68 7582 UIDNOTSTICKY (response code) 106 7583 UIDVALIDITY (response code) 106 7584 UIDVALIDITY (status item) 68 7585 UNANSWERED (search key) 80 7586 UNAVAILABLE (response code) 107 7587 UNDELETED (search key) 80 7588 UNDRAFT (search key) 80 7589 UNFLAGGED (search key) 80 7590 UNKEYWORD (search key) 80 7591 UNKNOWN-CTE (response code) 107 7592 UNSEEN (search key) 80 7593 UNSEEN (status item) 68 7594 UNSELECT (command) 74 7595 UNSUBSCRIBE (command) 44 7596 Unique Identifier (UID) (message attribute) 9 7598 [ 7599 [RFC-5322] Size (message attribute) 14 7601 \ 7602 \All (mailbox name attribute) 113 7603 \Answered (system flag) 12 7604 \Archive (mailbox name attribute) 113 7605 \Deleted (system flag) 12 7606 \Draft (system flag) 12 7607 \Drafts (mailbox name attribute) 113 7608 \Flagged (mailbox name attribute) 113 7609 \Flagged (system flag) 12 7610 \HasChildren (mailbox name attribute) 111 7611 \HasNoChildren (mailbox name attribute) 112 7612 \Junk (mailbox name attribute) 113 7613 \Marked (mailbox name attribute) 112 7614 \Noinferiors (mailbox name attribute) 111 7615 \NonExistent (mailbox name attribute) 111 7616 \Noselect (mailbox name attribute) 111 7617 \Recent (system flag) 12 7618 \Remote (mailbox name attribute) 112 7619 \Seen (system flag) 12 7620 \Sent (mailbox name attribute) 113 7621 \Subscribed (mailbox name attribute) 112 7622 \Trash (mailbox name attribute) 113 7623 \Unmarked (mailbox name attribute) 112 7625 Authors' Addresses 7627 Alexey Melnikov (editor) 7628 Isode Ltd 7629 14 Castle Mews 7630 Hampton, Middlesex TW12 2NP 7631 UK 7633 Email: Alexey.Melnikov@isode.com 7634 Barry Leiba (editor) 7635 Futurewei Technologies 7637 Phone: +1 646 827 0648 7638 Email: barryleiba@computer.org 7639 URI: http://internetmessagingtechnology.org/