idnits 2.17.00 (12 Aug 2021) /tmp/idnits11132/draft-ietf-extra-imap4rev2-20.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 (October 27, 2020) is 570 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 7068, but not defined == Missing Reference: 'IMAP-OBSOLETE' is mentioned on line 7063, but not defined == Missing Reference: 'IMAP-COMPAT' is mentioned on line 7053, but not defined == Missing Reference: 'IMAP-HISTORICAL' is mentioned on line 7058, but not defined == Missing Reference: 'RFC-822' is mentioned on line 7072, but not defined ** Obsolete undefined reference: RFC 822 (Obsoleted by RFC 2822) == Missing Reference: 'IMAP-MODEL' is mentioned on line 7002, but not defined == Missing Reference: 'IMAP-DISC' is mentioned on line 6991, but not defined == Missing Reference: 'RFC3503' is mentioned on line 6964, but not defined == Missing Reference: 'IMAP-KEYWORDS-REG' is mentioned on line 7031, but not defined == Missing Reference: 'SMTP' is mentioned on line 7012, but not defined == Missing Reference: 'RFC7888' is mentioned on line 6987, but not defined -- Looks like a reference, but probably isn't: '1' on line 892 == Missing Reference: 'IMAP-URL' is mentioned on line 7026, but not defined == Missing Reference: 'TLS' is mentioned on line 1197, but not defined == Missing Reference: 'UIDVALIDITY 3857529045' is mentioned on line 5769, but not defined == Missing Reference: 'UIDNEXT 4392' is mentioned on line 1734, but not defined == Missing Reference: 'RFC2193' is mentioned on line 6974, but not defined == Missing Reference: 'RFC3348' is mentioned on line 7320, but not defined ** Obsolete undefined reference: RFC 3348 (Obsoleted by RFC 5258) == Missing Reference: 'RFC4314' is mentioned on line 7019, but not defined == Missing Reference: 'RFC3501' is mentioned on line 7049, but not defined ** Obsolete undefined reference: RFC 3501 (Obsoleted by RFC 9051) == Missing Reference: 'UIDNEXT 2' is mentioned on line 3264, but not defined == Missing Reference: 'UIDVALIDITY 1' is mentioned on line 3336, but not defined == Missing Reference: 'CHARSET-REG' is mentioned on line 7041, but not defined == Missing Reference: 'IMAP-I18N' is mentioned on line 6996, but not defined == Missing Reference: 'HEADER' is mentioned on line 5787, but not defined == Missing Reference: 'BADCHARSET UTF-8' is mentioned on line 3916, but not defined == Missing Reference: 'UID' is mentioned on line 4344, but not defined == Missing Reference: 'RFC2087' is mentioned on line 7023, but not defined ** Obsolete undefined reference: RFC 2087 (Obsoleted by RFC 9208) == Missing Reference: 'IMAP-MAILBOX-NAME-ATTRS-REG' is mentioned on line 7036, but not defined == Missing Reference: 'READ-WRITE' is mentioned on line 5771, but not defined == Missing Reference: 'RFC4422' is mentioned on line 6118, but not defined == Missing Reference: 'IMAP4' is mentioned on line 6203, but not defined == Missing Reference: 'Namespace-Response-Extensions' is mentioned on line 6273, but not defined == Missing Reference: 'IMAP-TLS' is mentioned on line 7076, but not defined == Missing Reference: 'RFCXXXX' is mentioned on line 6804, but not defined == Missing Reference: 'RFC5465' is mentioned on line 6983, but not defined == Missing Reference: 'RFC5256' is mentioned on line 6969, but not defined == Missing Reference: 'IMAP-UTF-8' is mentioned on line 7095, but not defined == Missing Reference: 'RFC3516' is mentioned on line 7187, 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: April 30, 2021 October 27, 2020 8 Internet Message Access Protocol (IMAP) - Version 4rev2 9 draft-ietf-extra-imap4rev2-20 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 April 30, 2021. 49 Copyright Notice 51 Copyright (c) 2020 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) . . . 23 116 6. Client Commands . . . . . . . . . . . . . . . . . . . . . . . 25 117 6.1. Client Commands - Any State . . . . . . . . . . . . . . . 25 118 6.1.1. CAPABILITY Command . . . . . . . . . . . . . . . . . 25 119 6.1.2. NOOP Command . . . . . . . . . . . . . . . . . . . . 26 120 6.1.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . 27 121 6.2. Client Commands - Not Authenticated State . . . . . . . . 27 122 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 . . . . . . . . . . . . . . . . . . . 39 131 6.3.6. RENAME Command . . . . . . . . . . . . . . . . . . . 41 132 6.3.7. SUBSCRIBE Command . . . . . . . . . . . . . . . . . . 43 133 6.3.8. UNSUBSCRIBE Command . . . . . . . . . . . . . . . . . 44 134 6.3.9. LIST Command . . . . . . . . . . . . . . . . . . . . 44 135 6.3.10. NAMESPACE Command . . . . . . . . . . . . . . . . . . 62 136 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 6.5.1. X Command . . . . . . . . . . . . . . . . . . . 97 151 7. Server Responses . . . . . . . . . . . . . . . . . . . . . . 98 152 7.1. Server Responses - Status Responses . . . . . . . . . . . 99 153 7.1.1. OK Response . . . . . . . . . . . . . . . . . . . . . 107 154 7.1.2. NO Response . . . . . . . . . . . . . . . . . . . . . 108 155 7.1.3. BAD Response . . . . . . . . . . . . . . . . . . . . 108 156 7.1.4. PREAUTH Response . . . . . . . . . . . . . . . . . . 108 157 7.1.5. BYE Response . . . . . . . . . . . . . . . . . . . . 109 158 7.2. Server Responses - Server and Mailbox Status . . . . . . 109 159 7.2.1. The ENABLED Response . . . . . . . . . . . . . . . . 110 160 7.2.2. CAPABILITY Response . . . . . . . . . . . . . . . . . 110 161 7.2.3. LIST Response . . . . . . . . . . . . . . . . . . . . 111 162 7.2.4. NAMESPACE Response . . . . . . . . . . . . . . . . . 115 163 7.2.5. STATUS Response . . . . . . . . . . . . . . . . . . . 115 164 7.2.6. ESEARCH Response . . . . . . . . . . . . . . . . . . 115 165 7.2.7. FLAGS Response . . . . . . . . . . . . . . . . . . . 116 166 7.3. Server Responses - Mailbox Size . . . . . . . . . . . . . 116 167 7.3.1. EXISTS Response . . . . . . . . . . . . . . . . . . . 116 168 7.4. Server Responses - Message Status . . . . . . . . . . . . 117 169 7.4.1. EXPUNGE Response . . . . . . . . . . . . . . . . . . 117 170 7.4.2. FETCH Response . . . . . . . . . . . . . . . . . . . 118 171 7.5. Server Responses - Command Continuation Request . . . . . 124 172 8. Sample IMAP4rev2 connection . . . . . . . . . . . . . . . . . 124 173 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 125 174 10. Author's Note . . . . . . . . . . . . . . . . . . . . . . . . 143 175 11. Security Considerations . . . . . . . . . . . . . . . . . . . 143 176 11.1. STARTTLS Security Considerations . . . . . . . . . . . . 143 177 11.2. COPYUID and APPENDUID response codes . . . . . . . . . . 144 178 11.3. LIST command and Other Users' namespace . . . . . . . . 144 179 11.4. Other Security Considerations . . . . . . . . . . . . . 144 180 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 145 181 12.1. Updates to IMAP4 Capabilities registry . . . . . . . . . 146 182 12.2. GSSAPI/SASL service name . . . . . . . . . . . . . . . . 146 183 12.3. LIST Selection Options, LIST Return Options, LIST 184 extended data items . . . . . . . . . . . . . . . . . . 146 185 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 146 186 13.1. Normative References . . . . . . . . . . . . . . . . . . 146 187 13.2. Informative References (related protocols) . . . . . . . 150 188 13.3. Informative References (historical aspects of IMAP and 189 related protocols) . . . . . . . . . . . . . . . . . . . 152 190 Appendix A. Backward compatibility with IMAP4rev1 . . . . . . . 152 191 A.1. Mailbox International Naming Convention for compatibility 192 with IMAP4rev1 . . . . . . . . . . . . . . . . . . . . . 153 194 Appendix B. Backward compatibility with BINARY extension . . . . 154 195 Appendix C. Backward compatibility with LIST-EXTENDED extension 155 196 Appendix D. Changes from RFC 3501 / IMAP4rev1 . . . . . . . . . 155 197 Appendix E. Other Recommended IMAP Extensions . . . . . . . . . 156 198 Appendix F. Acknowledgement . . . . . . . . . . . . . . . . . . 157 199 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 200 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 163 202 1. How to Read This Document 204 1.1. Organization of This Document 206 This document is written from the point of view of the implementor of 207 an IMAP4rev2 client or server. Beyond the protocol overview in 208 section 2, it is not optimized for someone trying to understand the 209 operation of the protocol. The material in sections 3 through 5 210 provides the general context and definitions with which IMAP4rev2 211 operates. 213 Sections 6, 7, and 9 describe the IMAP commands, responses, and 214 syntax, respectively. The relationships among these are such that it 215 is almost impossible to understand any of them separately. In 216 particular, do not attempt to deduce command syntax from the command 217 section alone; instead refer to the Formal Syntax section. 219 1.2. Conventions Used in This Document 221 "Conventions" are basic principles or procedures. Document 222 conventions are noted in this section. 224 In examples, "C:" and "S:" indicate lines sent by the client and 225 server respectively. 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 [IMAP2] and 272 unpublished IMAP2bis protocols. IMAP4rev2 is largely compatible with 273 the IMAP4rev1 protocol described in RFC 3501 and the IMAP4 protocol 274 described in RFC 1730; the exception being in certain facilities 275 added in RFC 1730 and RFC 3501 that proved problematic and were 276 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 D, 281 Appendix A and [IMAP-OBSOLETE]. IMAP4rev2 compatibility with BINARY 282 and LIST-EXTENDED IMAP extensions are described in Appendix B and 283 Appendix C respectively. 285 Other compatibility issues with IMAP2bis, the most common variant of 286 the earlier protocol, are discussed in [IMAP-COMPAT]. A full 287 discussion of compatibility issues with rare (and presumed extinct) 288 variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is 289 primarily of historical interest. 291 IMAP was originally developed for the older [RFC-822] standard, and 292 as a consequence several fetch items in IMAP incorporate "RFC822" in 293 their name. In all cases, "RFC822" should be interpreted as a 294 reference to the updated [RFC-5322] standard. 296 2. Protocol Overview 298 2.1. Link Level 300 The IMAP4rev2 protocol assumes a reliable data stream such as that 301 provided by TCP. When TCP is used, an IMAP4rev2 server listens on 302 port 143 or port 993 (IMAP-over-TLS). 304 2.2. Commands and Responses 306 An IMAP4rev2 connection consists of the establishment of a client/ 307 server network connection, an initial greeting from the server, and 308 client/server interactions. These client/server interactions consist 309 of a client command, server data, and a server completion result 310 response. 312 All interactions transmitted by client and server are in the form of 313 lines, that is, strings that end with a CRLF. The protocol receiver 314 of an IMAP4rev2 client or server is either reading a line, or is 315 reading a sequence of octets with a known count followed by a line. 317 2.2.1. Client Protocol Sender and Server Protocol Receiver 319 The client command begins an operation. Each client command is 320 prefixed with an identifier (typically a short alphanumeric string, 321 e.g., A0001, A0002, etc.) called a "tag". A different tag is 322 generated by the client for each command. (More formally: the client 323 SHOULD generate a unique tag for every command, but a server MUST 324 accept tag reuse.) 326 Clients MUST follow the syntax outlined in this specification 327 strictly. It is a syntax error to send a command with missing or 328 extraneous spaces or arguments. 330 There are two cases in which a line from the client does not 331 represent a complete command. In one case, a command argument is 332 quoted with an octet count (see the description of literal in String 333 under Data Formats); in the other case, the command arguments require 334 server feedback (see the AUTHENTICATE command). In either case, the 335 server sends a command continuation request response if it is ready 336 for the octets (if appropriate) and the remainder of the command. 337 This response is prefixed with the token "+". 339 Note: If instead, the server detected an error in the command, it 340 sends a BAD completion response with a tag matching the command 341 (as described below) to reject the command and prevent the client 342 from sending any more of the command. 344 It is also possible for the server to send a completion response 345 for some other command (if multiple commands are in progress), or 346 untagged data. In either case, the command continuation request 347 is still pending; the client takes the appropriate action for the 348 response, and reads another response from the server. In all 349 cases, the client MUST send a complete command (including 350 receiving all command continuation request responses and command 351 continuations for the command) before initiating a new command. 353 The protocol receiver of an IMAP4rev2 server reads a command line 354 from the client, parses the command and its arguments, and transmits 355 server data and a server command completion result response. 357 2.2.2. Server Protocol Sender and Client Protocol Receiver 359 Data transmitted by the server to the client and status responses 360 that do not indicate command completion are prefixed with the token 361 "*", and are called untagged responses. 363 Server data MAY be sent as a result of a client command, or MAY be 364 sent unilaterally by the server. There is no syntactic difference 365 between server data that resulted from a specific command and server 366 data that were sent unilaterally. 368 The server completion result response indicates the success or 369 failure of the operation. It is tagged with the same tag as the 370 client command which began the operation. Thus, if more than one 371 command is in progress, the tag in a server completion response 372 identifies the command to which the response applies. There are 373 three possible server completion responses: OK (indicating success), 374 NO (indicating failure), or BAD (indicating a protocol error such as 375 unrecognized command or command syntax error). 377 Servers SHOULD enforce the syntax outlined in this specification 378 strictly. Any client command with a protocol syntax error, including 379 (but not limited to) missing or extraneous spaces or arguments, 380 SHOULD be rejected, and the client given a BAD server completion 381 response. 383 The protocol receiver of an IMAP4rev2 client reads a response line 384 from the server. It then takes action on the response based upon the 385 first token of the response, which can be a tag, a "*", or a "+". 387 A client MUST be prepared to accept any server response at all times. 388 This includes server data that was not requested. Server data SHOULD 389 be recorded, so that the client can reference its recorded copy 390 rather than sending a command to the server to request the data. In 391 the case of certain server data, the data MUST be recorded. 393 This topic is discussed in greater detail in the Server Responses 394 section. 396 2.3. Message Attributes 398 In addition to message text, each message has several attributes 399 associated with it. These attributes can be retrieved individually 400 or in conjunction with other attributes or message texts. 402 2.3.1. Message Numbers 404 Messages in IMAP4rev2 are accessed by one of two numbers; the unique 405 identifier or the message sequence number. 407 2.3.1.1. Unique Identifier (UID) Message Attribute 409 An unsigned non-zero 32-bit value assigned to each message, which 410 when used with the unique identifier validity value (see below) forms 411 a 64-bit value that MUST NOT refer to any other message in the 412 mailbox or any subsequent mailbox with the same name forever. Unique 413 identifiers are assigned in a strictly ascending fashion in the 414 mailbox; as each message is added to the mailbox it is assigned a 415 higher UID than the message(s) which were added previously. Unlike 416 message sequence numbers, unique identifiers are not necessarily 417 contiguous. 419 The unique identifier of a message MUST NOT change during the 420 session, and SHOULD NOT change between sessions. Any change of 421 unique identifiers between sessions MUST be detectable using the 422 UIDVALIDITY mechanism discussed below. Persistent unique identifiers 423 are required for a client to resynchronize its state from a previous 424 session with the server (e.g., disconnected or offline access clients 425 [IMAP-MODEL]); this is discussed further in [IMAP-DISC]. 427 Associated with every mailbox are two 32-bit unsigned non-zero values 428 which aid in unique identifier handling: the next unique identifier 429 value (UIDNEXT) and the unique identifier validity value 430 (UIDVALIDITY). 432 The next unique identifier value is the predicted value that will be 433 assigned to a new message in the mailbox. Unless the unique 434 identifier validity also changes (see below), the next unique 435 identifier value MUST have the following two characteristics. First, 436 the next unique identifier value MUST NOT change unless new messages 437 are added to the mailbox; and second, the next unique identifier 438 value MUST change whenever new messages are added to the mailbox, 439 even if those new messages are subsequently expunged. 441 Note: The next unique identifier value is intended to provide a 442 means for a client to determine whether any messages have been 443 delivered to the mailbox since the previous time it checked this 444 value. It is not intended to provide any guarantee that any 445 message will have this unique identifier. A client can only 446 assume, at the time that it obtains the next unique identifier 447 value, that messages arriving after that time will have a UID 448 greater than or equal to that value. 450 The unique identifier validity value is sent in a UIDVALIDITY 451 response code in an OK untagged response at mailbox selection time. 452 If unique identifiers from an earlier session fail to persist in this 453 session, the unique identifier validity value MUST be greater than 454 the one used in the earlier session. A good UIDVALIDITY value to use 455 is a 32-bit representation of the current date/time when the value is 456 assigned: this ensures that the value is unique and always increases. 457 Another possible alternative is a global counter that gets 458 incremented every time a mailbox is created. 460 Note: Ideally, unique identifiers SHOULD persist at all times. 461 Although this specification recognizes that failure to persist can 462 be unavoidable in certain server environments, it STRONGLY 463 ENCOURAGES message store implementation techniques that avoid this 464 problem. For example: 466 1. Unique identifiers MUST be strictly ascending in the mailbox 467 at all times. If the physical message store is re-ordered by 468 a non-IMAP agent, this requires that the unique identifiers in 469 the mailbox be regenerated, since the former unique 470 identifiers are no longer strictly ascending as a result of 471 the re-ordering. 473 2. If the message store has no mechanism to store unique 474 identifiers, it must regenerate unique identifiers at each 475 session, and each session must have a unique UIDVALIDITY 476 value. 478 3. If the mailbox is deleted/renamed and a new mailbox with the 479 same name is created at a later date, the server must either 480 keep track of unique identifiers from the previous instance of 481 the mailbox, or it must assign a new UIDVALIDITY value to the 482 new instance of the mailbox. 484 4. The combination of mailbox name, UIDVALIDITY, and UID must 485 refer to a single immutable (or expunged) message on that 486 server forever. In particular, the internal date, [RFC-5322] 487 size, envelope, body structure, and message texts (all 488 BODY[...] fetch data items) must never change. This does not 489 include message numbers, nor does it include attributes that 490 can be set by a STORE command (e.g., FLAGS). When a message 491 is expunged, its UID MUST NOT be reused under the same 492 UIDVALIDITY value. 494 2.3.1.2. Message Sequence Number Message Attribute 496 A relative position from 1 to the number of messages in the mailbox. 497 This position MUST be ordered by ascending unique identifier. As 498 each new message is added, it is assigned a message sequence number 499 that is 1 higher than the number of messages in the mailbox before 500 that new message was added. 502 Message sequence numbers can be reassigned during the session. For 503 example, when a message is permanently removed (expunged) from the 504 mailbox, the message sequence number for all subsequent messages is 505 decremented. The number of messages in the mailbox is also 506 decremented. Similarly, a new message can be assigned a message 507 sequence number that was once held by some other message prior to an 508 expunge. 510 In addition to accessing messages by relative position in the 511 mailbox, message sequence numbers can be used in mathematical 512 calculations. For example, if an untagged "11 EXISTS" is received, 513 and previously an untagged "8 EXISTS" was received, three new 514 messages have arrived with message sequence numbers of 9, 10, and 11. 515 Another example, if message 287 in a 523 message mailbox has UID 516 12345, there are exactly 286 messages which have lesser UIDs and 236 517 messages which have greater UIDs. 519 2.3.2. Flags Message Attribute 521 A list of zero or more named tokens associated with the message. A 522 flag is set by its addition to this list, and is cleared by its 523 removal. There are two types of flags in IMAP4rev2. A flag of 524 either type can be permanent or session-only. 526 A system flag is a flag name that is pre-defined in this 527 specification and begin with "\". Certain system flags (\Deleted and 528 \Seen) have special semantics described elsewhere in this document. 529 The currently-defined system flags are: 531 \Seen Message has been read 533 \Answered Message has been answered 535 \Flagged Message is "flagged" for urgent/special attention 537 \Deleted Message is "deleted" for removal by later EXPUNGE 539 \Draft Message has not completed composition (marked as a draft). 541 \Recent This flag was in used in IMAP4rev1 and is now deprecated. 543 A keyword is defined by the server implementation. Keywords do not 544 begin with "\". Servers MAY permit the client to define new keywords 545 in the mailbox (see the description of the PERMANENTFLAGS response 546 code for more information). Some keywords that start with "$" are 547 also defined in this specification. 549 This document defines several keywords that were not originally 550 defined in RFC 3501, but which were found to be useful by client 551 implementations. These keywords SHOULD be supported (i.e. allowed in 552 SEARCH, allowed and preserved in APPEND, COPY, MOVE commands) by 553 server implementations: 555 $Forwarded Message has been forwarded to another email address, 556 embedded within or attached to a new message. An email client 557 sets this keyword when it successfully forwards the message to 558 another email address. Typical usage of this keyword is to show a 559 different (or additional) icon for a message that has been 560 forwarded. Once set, the flag SHOULD NOT be cleared. 562 $MDNSent Message Disposition Notification [RFC8098] was generated 563 and sent for this message. See [RFC3503] for more details on how 564 this keyword is used. 566 $Junk The user (or a delivery agent on behalf of the user) may 567 choose to mark a message as definitely containing junk ($Junk; see 568 also the related keyword $NotJunk). The $Junk keyword can be used 569 to mark (and potentially move/delete messages later), group or 570 hide undesirable messages. See [IMAP-KEYWORDS-REG] for more 571 information. 573 $NotJunk The user (or a delivery agent on behalf of the user) may 574 choose to mark a message as definitely not containing junk 575 ($NotJunk; see also the related keyword $Junk). The $NotJunk 576 keyword can be used to mark, group or show messages that the user 577 wants to see. See [IMAP-KEYWORDS-REG] for more information. 579 $Phishing The $Phishing keyword can be used by a delivery agent to 580 mark a message as highly likely to be a phishing email. An email 581 that's determined to be a phishing email by the delivery agent 582 should also be considered a junk email and have the appropriate 583 junk filtering applied, including setting the $Junk flag and 584 placing in the \Junk special-use mailbox (see Section 7.2.3) if 585 available. 586 If both the $Phishing flag and the $Junk flag are set, the user 587 agent should display an additional warning message to the user. 588 User agents should not use the term "phishing" in their warning 589 message as most users do not understand this term. Phrasing of 590 the form "this message may be trying to steal your personal 591 information" is recommended. Additionally the user agent may 592 display a warning when clicking on any hyperlinks within the 593 message. 594 The requirement for both $Phishing and $Junk to be set before a 595 user agent displays a warning is for better backwards 596 compatibility with existing clients that understand the $Junk flag 597 but not the $Phishing flag. This so that when an unextended 598 client removes the $Junk flag, an extended client will also show 599 the correct state. See [IMAP-KEYWORDS-REG] for more information. 601 $Junk and $NotJunk are mutually exclusive. If more than one of them 602 is set for a message, the client MUST treat this as if none of them 603 is set and SHOULD unset both of them on the IMAP server. 605 Other registered keywords can be found in the "IMAP and JMAP 606 Keywords" registry [IMAP-KEYWORDS-REG]. New keywords SHOULD be 607 registered in this registry using the procedure specified in 608 [RFC5788]. 610 A flag can be permanent or session-only on a per-flag basis. 611 Permanent flags are those which the client can add or remove from the 612 message flags permanently; that is, concurrent and subsequent 613 sessions will see any change in permanent flags. Changes to session 614 flags are valid only in that session. 616 2.3.3. Internal Date Message Attribute 618 The internal date and time of the message on the server. This is not 619 the date and time in the [RFC-5322] header, but rather a date and 620 time which reflects when the message was received. In the case of 621 messages delivered via [SMTP], this SHOULD be the date and time of 622 final delivery of the message as defined by [SMTP]. In the case of 623 messages delivered by the IMAP4rev2 COPY or MOVE command, this SHOULD 624 be the internal date and time of the source message. In the case of 625 messages delivered by the IMAP4rev2 APPEND command, this SHOULD be 626 the date and time as specified in the APPEND command description. 627 All other cases are implementation defined. 629 2.3.4. [RFC-5322] Size Message Attribute 631 The number of octets in the message, as expressed in [RFC-5322] 632 format. 634 2.3.5. Envelope Structure Message Attribute 636 A parsed representation of the [RFC-5322] header of the message. 637 Note that the IMAP Envelope structure is not the same as an [SMTP] 638 envelope. 640 2.3.6. Body Structure Message Attribute 642 A parsed representation of the [MIME-IMB] body structure information 643 of the message. 645 2.4. Message Texts 647 In addition to being able to fetch the full [RFC-5322] text of a 648 message, IMAP4rev2 permits the fetching of portions of the full 649 message text. Specifically, it is possible to fetch the [RFC-5322] 650 message header, [RFC-5322] message body, a [MIME-IMB] body part, or a 651 [MIME-IMB] header. 653 3. State and Flow Diagram 655 Once the connection between client and server is established, an 656 IMAP4rev2 connection is in one of four states. The initial state is 657 identified in the server greeting. Most commands are only valid in 658 certain states. It is a protocol error for the client to attempt a 659 command while the connection is in an inappropriate state, and the 660 server will respond with a BAD or NO (depending upon server 661 implementation) command completion result. 663 3.1. Not Authenticated State 665 In the not authenticated state, the client MUST supply authentication 666 credentials before most commands will be permitted. This state is 667 entered when a connection starts unless the connection has been pre- 668 authenticated. 670 3.2. Authenticated State 672 In the authenticated state, the client is authenticated and MUST 673 select a mailbox to access before commands that affect messages will 674 be permitted. This state is entered when a pre-authenticated 675 connection starts, when acceptable authentication credentials have 676 been provided, after an error in selecting a mailbox, or after a 677 successful CLOSE command. 679 3.3. Selected State 681 In a selected state, a mailbox has been selected to access. This 682 state is entered when a mailbox has been successfully selected. 684 3.4. Logout State 686 In the logout state, the connection is being terminated. This state 687 can be entered as a result of a client request (via the LOGOUT 688 command) or by unilateral action on the part of either the client or 689 server. 691 If the client requests the logout state, the server MUST send an 692 untagged BYE response and a tagged OK response to the LOGOUT command 693 before the server closes the connection; and the client MUST read the 694 tagged OK response to the LOGOUT command before the client closes the 695 connection. 697 A server SHOULD NOT unilaterally close the connection without sending 698 an untagged BYE response that contains the reason for having done so. 699 A client SHOULD NOT unilaterally close the connection, and instead 700 SHOULD issue a LOGOUT command. If the server detects that the client 701 has unilaterally closed the connection, the server MAY omit the 702 untagged BYE response and simply close its connection. 704 +----------------------+ 705 |connection established| 706 +----------------------+ 707 || 708 \/ 709 +--------------------------------------+ 710 | server greeting | 711 +--------------------------------------+ 712 || (1) || (2) || (3) 713 \/ || || 714 +-----------------+ || || 715 |Not Authenticated| || || 716 +-----------------+ || || 717 || (7) || (4) || || 718 || \/ \/ || 719 || +----------------+ || 720 || | Authenticated |<=++ || 721 || +----------------+ || || 722 || || (7) || (5) || (6) || 723 || || \/ || || 724 || || +--------+ || || 725 || || |Selected|==++ || 726 || || +--------+ || 727 || || || (7) || 728 \/ \/ \/ \/ 729 +--------------------------------------+ 730 | Logout | 731 +--------------------------------------+ 732 || 733 \/ 734 +-------------------------------+ 735 |both sides close the connection| 736 +-------------------------------+ 738 (1) connection without pre-authentication (OK greeting) 739 (2) pre-authenticated connection (PREAUTH greeting) 740 (3) rejected connection (BYE greeting) 741 (4) successful LOGIN or AUTHENTICATE command 742 (5) successful SELECT or EXAMINE command 743 (6) CLOSE command, unsolicited CLOSED response code or 744 failed SELECT or EXAMINE command 745 (7) LOGOUT command, server shutdown, or connection closed 747 4. Data Formats 749 IMAP4rev2 uses textual commands and responses. Data in IMAP4rev2 can 750 be in one of several forms: atom, number, string, parenthesized list, 751 or NIL. Note that a particular data item may take more than one 752 form; for example, a data item defined as using "astring" syntax may 753 be either an atom or a string. 755 4.1. Atom 757 An atom consists of one or more non-special characters. 759 4.1.1. Sequence set and UID set 761 A set of messages can be referenced by a sequence set containing 762 either message sequence numbers or unique identifiers. See Section 9 763 for details. Sequence sets can contain ranges (e.g. "5:50"), an 764 enumeration of specific message/UID numbers, a special symbol "*", or 765 a combination of the above. 767 A "UID set" is similar to the sequence set of unique identifiers; 768 however, the "*" value for a sequence number is not permitted. 770 4.2. Number 772 A number consists of one or more digit characters, and represents a 773 numeric value. 775 4.3. String 777 A string is in one of three forms: synchonizing literal, non- 778 synchronizing literal or quoted string. The synchronizing literal 779 form is the general form of string. The non-synchronizing literal 780 form is also the general form, but has length limitation. The quoted 781 string form is an alternative that avoids the overhead of processing 782 a literal at the cost of limitations of characters which may be used. 784 When the distinction between synchronizing and non-synchronizing 785 literals is not important, this document just uses the term 786 "literal". 788 A synchronizing literal is a sequence of zero or more octets 789 (including CR and LF), prefix-quoted with an octet count in the form 790 of an open brace ("{"), the number of octets, close brace ("}"), and 791 CRLF. In the case of synchronizing literals transmitted from server 792 to client, the CRLF is immediately followed by the octet data. In 793 the case of synchronizing literals transmitted from client to server, 794 the client MUST wait to receive a command continuation request 795 (described later in this document) before sending the octet data (and 796 the remainder of the command). 798 The non-synchronizing literal is an alternate form of synchronizing 799 literal, and it may appear in communication from client to server 800 instead of the synchonizing form of literal. The non-synchronizing 801 literal form MUST NOT be sent from server to client. The non- 802 synchronizing literal is distinguished from the synchronizing literal 803 by having a plus ("+") between the octet count and the closing brace 804 ("}"). The server does not generate a command continuation request 805 in response to a non-synchronizing literal, and clients are not 806 required to wait before sending the octets of a non- synchronizing 807 literal. Non-synchronizing literals MUST NOT be larger than 4096 808 octets. Any literal larger than 4096 bytes MUST be sent as a 809 synchronizing literal. (Non-synchronizing literals defined in this 810 document are the same as non-synchronizing literals defined by the 811 LITERAL- extension from [RFC7888]. See that document for details on 812 how to handle invalid non-synchronizing literals longer than 4096 813 octets and for interaction with other IMAP extensions.) 815 A quoted string is a sequence of zero or more Unicode characters, 816 excluding CR and LF, encoded in UTF-8, with double quote (<">) 817 characters at each end. 819 The empty string is represented as "" (a quoted string with zero 820 characters between double quotes), as {0} followed by CRLF (a 821 synchronizing literal with an octet count of 0) or as {0+} followed 822 by CRLF (a non-synchronizing literal with an octet count of 0). 824 Note: Even if the octet count is 0, a client transmitting a 825 synchronizing literal MUST wait to receive a command continuation 826 request. 828 4.3.1. 8-bit and Binary Strings 830 8-bit textual and binary mail is supported through the use of a 831 [MIME-IMB] content transfer encoding. IMAP4rev2 implementations MAY 832 transmit 8-bit or multi-octet characters in literals, but SHOULD do 833 so only when the [CHARSET] is identified. 835 IMAP4rev2 is compatible with [I18N-HDRS]. As a result, the 836 identified charset for header-field values with 8-bit content is 837 UTF-8 [UTF-8]. IMAP4rev2 implementations MUST accept and MAY 838 transmit [UTF-8] text in quoted-strings as long as the string does 839 not contain NUL, CR, or LF. This differs from IMAP4rev1 840 implementations. 842 Although a BINARY content transfer encoding is defined, unencoded 843 binary strings are not permitted, unless returned in a in 844 response to BINARY.PEEK[]<> or 845 BINARY[]<> FETCH data item. A "binary 846 string" is any string with NUL characters. A string with an 847 excessive amount of CTL characters MAY also be considered to be 848 binary. Unless returned in response to BINARY.PEEK[...]/BINARY[...] 849 FETCH, client and server implementations MUST encode binary data into 850 a textual form, such as BASE64, before transmitting the data. 852 4.4. Parenthesized List 854 Data structures are represented as a "parenthesized list"; a sequence 855 of data items, delimited by space, and bounded at each end by 856 parentheses. A parenthesized list can contain other parenthesized 857 lists, using multiple levels of parentheses to indicate nesting. 859 The empty list is represented as () -- a parenthesized list with no 860 members. 862 4.5. NIL 864 The special form "NIL" represents the non-existence of a particular 865 data item that is represented as a string or parenthesized list, as 866 distinct from the empty string "" or the empty parenthesized list (). 868 Note: NIL is never used for any data item which takes the form of 869 an atom. For example, a mailbox name of "NIL" is a mailbox named 870 NIL as opposed to a non-existent mailbox name. This is because 871 mailbox uses "astring" syntax which is an atom or a string. 872 Conversely, an addr-name of NIL is a non-existent personal name, 873 because addr-name uses "nstring" syntax which is NIL or a string, 874 but never an atom. 876 Examples: 878 The following LIST response: 880 * LIST () "/" NIL 882 is equivalent to: 883 * LIST () "/" "NIL" 885 as LIST response ABNF is using astring for mailbox name. 887 However, the following response 889 * FETCH 1 (BODY[1] NIL) 891 is not equivalent to: 892 * FETCH 1 (BODY[1] "NIL") 893 The former means absence of the body part, while the latter 894 means that it contains literal sequence of characters "NIL". 896 5. Operational Considerations 898 The following rules are listed here to ensure that all IMAP4rev2 899 implementations interoperate properly. 901 5.1. Mailbox Naming 903 In IMAP4rev2, Mailbox names are encoded in Net-Unicode [NET-UNICODE] 904 (this differs from IMAP4rev1). Client implementations MAY attempt to 905 create Net-Unicode mailbox names, and MUST interpret any 8-bit 906 mailbox names returned by LIST as [NET-UNICODE]. Server 907 implementations MUST prohibit the creation of 8-bit mailbox names 908 that do not comply with Net-Unicode. However, servers MAY accept a 909 de-normalized UTF-8 mailbox name and convert it to Unicode 910 normalization form "NFC" (as per Net-Unicode requirements) prior to 911 mailbox creation. Servers that choose to accept such de-normalized 912 UTF-8 mailbox names MUST accept them in all IMAP commands that have a 913 mailbox name parameter. In particular SELECT must open the 914 same mailbox that was successfully created with CREATE , even 915 if is a de-normalized UTF-8 mailbox name. 917 The case-insensitive mailbox name INBOX is a special name reserved to 918 mean "the primary mailbox for this user on this server". (Note that 919 this special name may not exist on some servers for some users, for 920 example if the user has no access to personal namespace.) The 921 interpretation of all other names is implementation-dependent. 923 In particular, this specification takes no position on case 924 sensitivity in non-INBOX mailbox names. Some server implementations 925 are fully case-sensitive in ASCII range; others preserve case of a 926 newly-created name but otherwise are case-insensitive; and yet others 927 coerce names to a particular case. Client implementations must be 928 able to interact with any of these. 930 There are certain client considerations when creating a new mailbox 931 name: 933 1. Any character which is one of the atom-specials (see the Formal 934 Syntax) will require that the mailbox name be represented as a 935 quoted string or literal. 937 2. CTL and other non-graphic characters are difficult to represent 938 in a user interface and are best avoided. Servers MAY refuse to 939 create mailbox names containing Unicode CTL characters. 941 3. Although the list-wildcard characters ("%" and "*") are valid in 942 a mailbox name, it is difficult to use such mailbox names with 943 the LIST command due to the conflict with wildcard 944 interpretation. 946 4. Usually, a character (determined by the server implementation) is 947 reserved to delimit levels of hierarchy. 949 5. Two characters, "#" and "&", have meanings by convention, and 950 should be avoided except when used in that convention. See 951 Section 5.1.2.1 and Appendix A.1 respectively. 953 5.1.1. Mailbox Hierarchy Naming 955 If it is desired to export hierarchical mailbox names, mailbox names 956 MUST be left-to-right hierarchical using a single character to 957 separate levels of hierarchy. The same hierarchy separator character 958 is used for all levels of hierarchy within a single name. 960 5.1.2. Namespaces 962 Personal Namespace: A namespace that the server considers within the 963 personal scope of the authenticated user on a particular connection. 964 Typically, only the authenticated user has access to mailboxes in 965 their Personal Namespace. It is the part of the namespace that 966 belongs to the user that is allocated for mailboxes. If an INBOX 967 exists for a user, it MUST appear within the user's personal 968 namespace. In the typical case, there SHOULD be only one Personal 969 Namespace on a server. 971 Other Users' Namespace: A namespace that consists of mailboxes from 972 the Personal Namespaces of other users. To access mailboxes in the 973 Other Users' Namespace, the currently authenticated user MUST be 974 explicitly granted access rights. For example, it is common for a 975 manager to grant to their secretary access rights to their mailbox. 976 In the typical case, there SHOULD be only one Other Users' Namespace 977 on a server. 979 Shared Namespace: A namespace that consists of mailboxes that are 980 intended to be shared amongst users and do not exist within a user's 981 Personal Namespace. 983 The namespaces a server uses MAY differ on a per-user basis. 985 5.1.2.1. Historic Mailbox Namespace Naming Convention 987 By convention, the first hierarchical element of any mailbox name 988 which begins with "#" identifies the "namespace" of the remainder of 989 the name. This makes it possible to disambiguate between different 990 types of mailbox stores, each of which have their own namespaces. 992 For example, implementations which offer access to USENET 993 newsgroups MAY use the "#news" namespace to partition the USENET 994 newsgroup namespace from that of other mailboxes. Thus, the 995 comp.mail.misc newsgroup would have a mailbox name of 996 "#news.comp.mail.misc", and the name "comp.mail.misc" can refer to 997 a different object (e.g., a user's private mailbox). 999 Namespaces that include the "#" character are not IMAP URL [IMAP-URL] 1000 friendly requiring the "#" character to be represented as %23 when 1001 within URLs. As such, server implementers MAY instead consider using 1002 namespace prefixes that do not contain the "#" character. 1004 5.1.2.2. Common namespace models 1006 Previous version of this protocol does not define a default server 1007 namespace. Two common namespace models have evolved: 1009 The "Personal Mailbox" model, in which the default namespace that is 1010 presented consists of only the user's personal mailboxes. To access 1011 shared mailboxes, the user must use an escape mechanism to reach 1012 another namespace. 1014 The "Complete Hierarchy" model, in which the default namespace that 1015 is presented includes the user's personal mailboxes along with any 1016 other mailboxes they have access to. 1018 5.2. Mailbox Size and Message Status Updates 1020 At any time, a server can send data that the client did not request. 1021 Sometimes, such behavior is REQUIRED. For example, agents other than 1022 the server MAY add messages to the mailbox (e.g., new message 1023 delivery), change the flags of the messages in the mailbox (e.g., 1024 simultaneous access to the same mailbox by multiple agents), or even 1025 remove messages from the mailbox. A server MUST send mailbox size 1026 updates automatically if a mailbox size change is observed during the 1027 processing of a command. A server SHOULD send message flag updates 1028 automatically, without requiring the client to request such updates 1029 explicitly. 1031 Special rules exist for server notification of a client about the 1032 removal of messages to prevent synchronization errors; see the 1033 description of the EXPUNGE response for more detail. In particular, 1034 it is NOT permitted to send an EXISTS response that would reduce the 1035 number of messages in the mailbox; only the EXPUNGE response can do 1036 this. 1038 Regardless of what implementation decisions a client makes on 1039 remembering data from the server, a client implementation MUST record 1040 mailbox size updates. It MUST NOT assume that any command after the 1041 initial mailbox selection will return the size of the mailbox. 1043 5.3. Response when no Command in Progress 1045 Server implementations are permitted to send an untagged response 1046 (except for EXPUNGE) while there is no command in progress. Server 1047 implementations that send such responses MUST deal with flow control 1048 considerations. Specifically, they MUST either (1) verify that the 1049 size of the data does not exceed the underlying transport's available 1050 window size, or (2) use non-blocking writes. 1052 5.4. Autologout Timer 1054 If a server has an inactivity autologout timer that applies to 1055 sessions after authentication, the duration of that timer MUST be at 1056 least 30 minutes. The receipt of ANY command from the client during 1057 that interval SHOULD suffice to reset the autologout timer. 1059 5.5. Multiple Commands in Progress (Command Pipelining) 1061 The client MAY send another command without waiting for the 1062 completion result response of a command, subject to ambiguity rules 1063 (see below) and flow control constraints on the underlying data 1064 stream. Similarly, a server MAY begin processing another command 1065 before processing the current command to completion, subject to 1066 ambiguity rules. However, any command continuation request responses 1067 and command continuations MUST be negotiated before any subsequent 1068 command is initiated. 1070 The exception is if an ambiguity would result because of a command 1071 that would affect the results of other commands. If the server 1072 detects a possible ambiguity, it MUST execute commands to completion 1073 in the order given by the client. 1075 The most obvious example of ambiguity is when a command would affect 1076 the results of another command, e.g., a FETCH of a message's flags 1077 and a STORE of that same message's flags. 1079 A non-obvious ambiguity occurs with commands that permit an untagged 1080 EXPUNGE response (commands other than FETCH, STORE, and SEARCH), 1081 since an untagged EXPUNGE response can invalidate sequence numbers in 1082 a subsequent command. This is not a problem for FETCH, STORE, or 1083 SEARCH commands because servers are prohibited from sending EXPUNGE 1084 responses while any of those commands are in progress. Therefore, if 1085 the client sends any command other than FETCH, STORE, or SEARCH, it 1086 MUST wait for the completion result response before sending a command 1087 with message sequence numbers. 1089 Note: EXPUNGE responses are permitted while UID FETCH, UID STORE, 1090 and UID SEARCH are in progress. If the client sends a UID 1091 command, it MUST wait for a completion result response before 1092 sending a command which uses message sequence numbers (this may 1093 include UID SEARCH). Any message sequence numbers in an argument 1094 to UID SEARCH are associated with messages prior to the effect of 1095 any untagged EXPUNGE returned by the UID SEARCH. 1097 For example, the following non-waiting command sequences are invalid: 1099 FETCH + NOOP + STORE 1101 STORE + COPY + FETCH 1103 COPY + COPY 1105 The following are examples of valid non-waiting command sequences: 1107 FETCH + STORE + SEARCH + NOOP 1109 STORE + COPY + EXPUNGE 1111 UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting 1112 command sequence, depending upon whether or not the second UID 1113 SEARCH contains message sequence numbers. 1115 Use of SEARCH result variable (see Section 6.4.4.1) creates direct 1116 dependency between two commands. See Section 6.4.4.2 for more 1117 considerations about pipelining such dependent commands. 1119 6. Client Commands 1121 IMAP4rev2 commands are described in this section. Commands are 1122 organized by the state in which the command is permitted. Commands 1123 which are permitted in multiple states are listed in the minimum 1124 permitted state (for example, commands valid in authenticated and 1125 selected state are listed in the authenticated state commands). 1127 Command arguments, identified by "Arguments:" in the command 1128 descriptions below, are described by function, not by syntax. The 1129 precise syntax of command arguments is described in the Formal Syntax 1130 (Section 9). 1132 Some commands cause specific server responses to be returned; these 1133 are identified by "Responses:" in the command descriptions below. 1134 See the response descriptions in the Responses section for 1135 information on these responses, and the Formal Syntax section for the 1136 precise syntax of these responses. It is possible for server data to 1137 be transmitted as a result of any command. Thus, commands that do 1138 not specifically require server data specify "no specific responses 1139 for this command" instead of "none". 1141 The "Result:" in the command description refers to the possible 1142 tagged status responses to a command, and any special interpretation 1143 of these status responses. 1145 The state of a connection is only changed by successful commands 1146 which are documented as changing state. A rejected command (BAD 1147 response) never changes the state of the connection or of the 1148 selected mailbox. A failed command (NO response) generally does not 1149 change the state of the connection or of the selected mailbox; the 1150 exception being the SELECT and EXAMINE commands. 1152 6.1. Client Commands - Any State 1154 The following commands are valid in any state: CAPABILITY, NOOP, and 1155 LOGOUT. 1157 6.1.1. CAPABILITY Command 1159 Arguments: none 1161 Responses: REQUIRED untagged response: CAPABILITY 1162 Result: OK - capability completed 1163 BAD - command unknown or arguments invalid 1165 The CAPABILITY command requests a listing of capabilities that the 1166 server supports. The server MUST send a single untagged CAPABILITY 1167 response with "IMAP4rev2" as one of the listed capabilities before 1168 the (tagged) OK response. 1170 A capability name which begins with "AUTH=" indicates that the server 1171 supports that particular authentication mechanism. All such names 1172 are, by definition, part of this specification. For example, the 1173 authorization capability for an experimental "blurdybloop" 1174 authenticator would be "AUTH=XBLURDYBLOOP" and not 1175 "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP". 1177 Other capability names refer to extensions, revisions, or amendments 1178 to this specification. See the documentation of the CAPABILITY 1179 response for additional information. No capabilities, beyond the 1180 base IMAP4rev2 set defined in this specification, are enabled without 1181 explicit client action to invoke the capability. 1183 Client and server implementations MUST implement the STARTTLS, 1184 LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) capabilities. 1185 See the Security Considerations section for important information. 1187 See the section entitled "Client Commands - Experimental/Expansion" 1188 for information about the form of site or implementation-specific 1189 capabilities. 1191 Example: C: abcd CAPABILITY 1192 S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI 1193 LOGINDISABLED 1194 S: abcd OK CAPABILITY completed 1195 C: efgh STARTTLS 1196 S: efgh OK STARTLS completed 1197 1198 C: ijkl CAPABILITY 1199 S: * CAPABILITY IMAP4rev2 AUTH=GSSAPI AUTH=PLAIN 1200 S: ijkl OK CAPABILITY completed 1202 6.1.2. NOOP Command 1204 Arguments: none 1206 Responses: no specific responses for this command (but see below) 1208 Result: OK - noop completed 1209 BAD - command unknown or arguments invalid 1211 The NOOP command always succeeds. It does nothing. 1213 Since any command can return a status update as untagged data, the 1214 NOOP command can be used as a periodic poll for new messages or 1215 message status updates during a period of inactivity (the IDLE 1216 command Section 6.3.13 should be used instead of NOOP if real-time 1217 updates to mailbox state are desirable). The NOOP command can also 1218 be used to reset any inactivity autologout timer on the server. 1220 Example: C: a002 NOOP 1221 S: a002 OK NOOP completed 1222 . . . 1223 C: a047 NOOP 1224 S: * 22 EXPUNGE 1225 S: * 23 EXISTS 1226 S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted)) 1227 S: a047 OK NOOP completed 1229 6.1.3. LOGOUT Command 1231 Arguments: none 1233 Responses: REQUIRED untagged response: BYE 1235 Result: OK - logout completed 1236 BAD - command unknown or arguments invalid 1238 The LOGOUT command informs the server that the client is done with 1239 the connection. The server MUST send a BYE untagged response before 1240 the (tagged) OK response, and then close the network connection. 1242 Example: C: A023 LOGOUT 1243 S: * BYE IMAP4rev2 Server logging out 1244 S: A023 OK LOGOUT completed 1245 (Server and client then close the connection) 1247 6.2. Client Commands - Not Authenticated State 1249 In the not authenticated state, the AUTHENTICATE or LOGIN command 1250 establishes authentication and enters the authenticated state. The 1251 AUTHENTICATE command provides a general mechanism for a variety of 1252 authentication techniques, privacy protection, and integrity 1253 checking; whereas the LOGIN command uses a traditional user name and 1254 plaintext password pair and has no means of establishing privacy 1255 protection or integrity checking. 1257 The STARTTLS command is an alternate form of establishing session 1258 privacy protection and integrity checking, but does not by itself 1259 establish authentication or enter the authenticated state. 1261 Server implementations MAY allow access to certain mailboxes without 1262 establishing authentication. This can be done by means of the 1263 ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older 1264 convention is a LOGIN command using the userid "anonymous"; in this 1265 case, a password is required although the server may choose to accept 1266 any password. The restrictions placed on anonymous users are 1267 implementation-dependent. 1269 Once authenticated (including as anonymous), it is not possible to 1270 re-enter not authenticated state. 1272 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1273 the following commands are valid in the not authenticated state: 1274 STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations 1275 section for important information about these commands. 1277 6.2.1. STARTTLS Command 1279 Arguments: none 1281 Responses: no specific response for this command 1283 Result: OK - starttls completed, begin TLS negotiation 1284 BAD - STARTTLS received after a successful TLS 1285 negotiation or arguments invalid 1287 A TLS [TLS-1.3] negotiation begins immediately after the CRLF at the 1288 end of the tagged OK response from the server. Once a client issues 1289 a STARTTLS command, it MUST NOT issue further commands until a server 1290 response is seen and the TLS negotiation is complete. 1292 The server remains in the non-authenticated state, even if client 1293 credentials are supplied during the TLS negotiation. This does not 1294 preclude an authentication mechanism such as EXTERNAL (defined in 1295 [SASL]) from using client identity determined by the TLS negotiation. 1297 Once TLS has been started, the client MUST discard cached information 1298 about server capabilities and SHOULD re-issue the CAPABILITY command. 1299 This is necessary to protect against man-in- the-middle attacks which 1300 alter the capabilities list prior to STARTTLS. The server MAY 1301 advertise different capabilities, and in particular SHOULD NOT 1302 advertise the STARTTLS capability, after a successful STARTTLS 1303 command. 1305 Example: C: a001 CAPABILITY 1306 S: * CAPABILITY IMAP4rev2 STARTTLS LOGINDISABLED 1307 S: a001 OK CAPABILITY completed 1308 C: a002 STARTTLS 1309 S: a002 OK Begin TLS negotiation now 1310 1311 C: a003 CAPABILITY 1312 S: * CAPABILITY IMAP4rev2 AUTH=PLAIN 1313 S: a003 OK CAPABILITY completed 1314 C: a004 LOGIN joe password 1315 S: a004 OK LOGIN completed 1317 6.2.2. AUTHENTICATE Command 1319 Arguments: SASL authentication mechanism name 1320 OPTIONAL initial response 1322 Responses: continuation data can be requested 1324 Result: OK - authenticate completed, now in authenticated state 1325 NO - authenticate failure: unsupported authentication 1326 mechanism, credentials rejected 1327 BAD - command unknown or arguments invalid, 1328 authentication exchange cancelled 1330 The AUTHENTICATE command indicates a [SASL] authentication mechanism 1331 to the server. If the server supports the requested authentication 1332 mechanism, it performs an authentication protocol exchange to 1333 authenticate and identify the client. It MAY also negotiate an 1334 OPTIONAL security layer for subsequent protocol interactions. If the 1335 requested authentication mechanism is not supported, the server 1336 SHOULD reject the AUTHENTICATE command by sending a tagged NO 1337 response. 1339 The AUTHENTICATE command supports the optional "initial response" 1340 feature defined in Section 5.1 of [SASL]. The client doesn't need to 1341 use it. If a SASL mechanism supports "initial response", but it is 1342 not specified by the client, the server handles this as specified in 1343 Section 3 of [SASL]. 1345 The service name specified by this protocol's profile of [SASL] is 1346 "imap". 1348 The authentication protocol exchange consists of a series of server 1349 challenges and client responses that are specific to the 1350 authentication mechanism. A server challenge consists of a command 1351 continuation request response with the "+" token followed by a BASE64 1352 encoded (see Section 4 of [RFC4648]) string. The client response 1353 consists of a single line consisting of a BASE64 encoded string. If 1354 the client wishes to cancel an authentication exchange, it issues a 1355 line consisting of a single "*". If the server receives such a 1356 response, or if it receives an invalid BASE64 string (e.g. 1357 characters outside the BASE64 alphabet, or non-terminal "="), it MUST 1358 reject the AUTHENTICATE command by sending a tagged BAD response. 1360 As with any other client response, this initial response MUST be 1361 encoded as BASE64. It also MUST be transmitted outside of a quoted 1362 string or literal. To send a zero-length initial response, the 1363 client MUST send a single pad character ("="). This indicates that 1364 the response is present, but is a zero-length string. 1366 When decoding the BASE64 data in the initial response, decoding 1367 errors MUST be treated as in any normal SASL client response, i.e. 1368 with a tagged BAD response. In particular, the server should check 1369 for any characters not explicitly allowed by the BASE64 alphabet, as 1370 well as any sequence of BASE64 characters that contains the pad 1371 character ('=') anywhere other than the end of the string (e.g., 1372 "=AAA" and "AAA=BBB" are not allowed). 1374 If the client uses an initial response with a SASL mechanism that 1375 does not support an initial response, the server MUST reject the 1376 command with a tagged BAD response. 1378 If a security layer is negotiated through the [SASL] authentication 1379 exchange, it takes effect immediately following the CRLF that 1380 concludes the authentication exchange for the client, and the CRLF of 1381 the tagged OK response for the server. 1383 While client and server implementations MUST implement the 1384 AUTHENTICATE command itself, it is not required to implement any 1385 authentication mechanisms other than the PLAIN mechanism described in 1386 [PLAIN]. Also, an authentication mechanism is not required to 1387 support any security layers. 1389 Note: a server implementation MUST implement a configuration in 1390 which it does NOT permit any plaintext password mechanisms, unless 1391 either the STARTTLS command has been negotiated or some other 1392 mechanism that protects the session from password snooping has 1393 been provided. Server sites SHOULD NOT use any configuration 1394 which permits a plaintext password mechanism without such a 1395 protection mechanism against password snooping. Client and server 1396 implementations SHOULD implement additional [SASL] mechanisms that 1397 do not use plaintext passwords, such the GSSAPI mechanism 1398 described in [SASL] and/or the SCRAM-SHA-256/SCRAM-SHA-256-PLUS 1399 [SCRAM-SHA-256] mechanisms. 1401 Servers and clients can support multiple authentication mechanisms. 1402 The server SHOULD list its supported authentication mechanisms in the 1403 response to the CAPABILITY command so that the client knows which 1404 authentication mechanisms to use. 1406 A server MAY include a CAPABILITY response code in the tagged OK 1407 response of a successful AUTHENTICATE command in order to send 1408 capabilities automatically. It is unnecessary for a client to send a 1409 separate CAPABILITY command if it recognizes these automatic 1410 capabilities. This should only be done if a security layer was not 1411 negotiated by the AUTHENTICATE command, because the tagged OK 1412 response as part of an AUTHENTICATE command is not protected by 1413 encryption/integrity checking. [SASL] requires the client to re- 1414 issue a CAPABILITY command in this case. The server MAY advertise 1415 different capabilities after a successful AUTHENTICATE command. 1417 If an AUTHENTICATE command fails with a NO response, the client MAY 1418 try another authentication mechanism by issuing another AUTHENTICATE 1419 command. It MAY also attempt to authenticate by using the LOGIN 1420 command (see Section 6.2.3 for more detail). In other words, the 1421 client MAY request authentication types in decreasing order of 1422 preference, with the LOGIN command as a last resort. 1424 The authorization identity passed from the client to the server 1425 during the authentication exchange is interpreted by the server as 1426 the user name whose privileges the client is requesting. 1428 Example: S: * OK IMAP4rev2 Server 1429 C: A001 AUTHENTICATE GSSAPI 1430 S: + 1431 C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw 1432 MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0 1433 b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW 1434 Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA 1435 cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX 1436 AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y 1437 C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb 1438 I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi 1439 vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL 1440 pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n 1441 FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE 1442 NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx 1443 O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB 1444 vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg== 1445 S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC 1446 AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0 1447 uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg== 1448 C: 1449 S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe 1450 ceP2CWY0SR0fAQAgAAQEBAQ= 1451 C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP 1452 wkhbfa2QteAQAgAG1yYwE= 1453 S: A001 OK GSSAPI authentication successful 1455 Note: The line breaks within server challenges and client responses 1456 are for editorial clarity and are not in real authenticators. 1458 6.2.3. LOGIN Command 1460 Arguments: user name 1461 password 1463 Responses: no specific responses for this command 1465 Result: OK - login completed, now in authenticated state 1466 NO - login failure: user name or password rejected 1467 BAD - command unknown or arguments invalid 1469 The LOGIN command identifies the client to the server and carries the 1470 plaintext password authenticating this user. 1472 A server MAY include a CAPABILITY response code in the tagged OK 1473 response to a successful LOGIN command in order to send capabilities 1474 automatically. It is unnecessary for a client to send a separate 1475 CAPABILITY command if it recognizes these automatic capabilities. 1477 Example: C: a001 LOGIN SMITH SESAME 1478 S: a001 OK LOGIN completed 1480 Note: Use of the LOGIN command over an insecure network (such as the 1481 Internet) is a security risk, because anyone monitoring network 1482 traffic can obtain plaintext passwords. The LOGIN command SHOULD NOT 1483 be used except as a last resort, and it is recommended that client 1484 implementations have a means to disable any automatic use of the 1485 LOGIN command. 1487 Unless either the client is accessing IMAP service on IMAPS port 1488 [RFC8314], the STARTTLS command has been negotiated or some other 1489 mechanism that protects the session from password snooping has been 1490 provided, a server implementation MUST implement a configuration in 1491 which it advertises the LOGINDISABLED capability and does NOT permit 1492 the LOGIN command. Server sites SHOULD NOT use any configuration 1493 which permits the LOGIN command without such a protection mechanism 1494 against password snooping. A client implementation MUST NOT send a 1495 LOGIN command if the LOGINDISABLED capability is advertised. 1497 6.3. Client Commands - Authenticated State 1499 In the authenticated state, commands that manipulate mailboxes as 1500 atomic entities are permitted. Of these commands, the SELECT and 1501 EXAMINE commands will select a mailbox for access and enter the 1502 selected state. 1504 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1505 the following commands are valid in the authenticated state: ENABLE, 1506 SELECT, EXAMINE, NAMESPACE, CREATE, DELETE, RENAME, SUBSCRIBE, 1507 UNSUBSCRIBE, LIST, STATUS, APPEND and IDLE. 1509 6.3.1. ENABLE Command 1511 Arguments: capability names 1513 Responses: no specific responses for this command 1515 Result: OK - Relevant capabilities enabled 1516 BAD - No arguments, or syntax error in an argument 1518 Several IMAP extensions allow the server to return unsolicited 1519 responses specific to these extensions in certain circumstances. 1520 However, servers cannot send those unsolicited responses (with the 1521 exception of response codes (see Section 7.1) included in tagged or 1522 untagged OK/NO/BAD responses, which can always be sent) until they 1523 know that the clients support such extensions and thus won't choke on 1524 the extension response data. 1526 The ENABLE command provides an explicit indication from the client 1527 that it supports particular extensions. It is designed such that the 1528 client can send a simple constant string with the extensions it 1529 supports, and the server will enable the shared subset that both 1530 support. 1532 The ENABLE command takes a list of capability names, and requests the 1533 server to enable the named extensions. Once enabled using ENABLE, 1534 each extension remains active until the IMAP connection is closed. 1535 For each argument, the server does the following: 1537 o If the argument is not an extension known to the server, the 1538 server MUST ignore the argument. 1540 o If the argument is an extension known to the server, and it is not 1541 specifically permitted to be enabled using ENABLE, the server MUST 1542 ignore the argument. (Note that knowing about an extension 1543 doesn't necessarily imply supporting that extension.) 1545 o If the argument is an extension that is supported by the server 1546 and that needs to be enabled, the server MUST enable the extension 1547 for the duration of the connection. Note that once an extension 1548 is enabled, there is no way to disable it. 1550 If the ENABLE command is successful, the server MUST send an untagged 1551 ENABLED response Section 7.2.1. 1553 Clients SHOULD only include extensions that need to be enabled by the 1554 server. For example, a client can enable IMAP4rev2 specific 1555 behaviour when both IMAP4rev1 and IMAP4rev2 are advertised in the 1556 CAPABILITY response. Future RFCs may add to this list. 1558 The ENABLE command is only valid in the authenticated state, before 1559 any mailbox is selected. Clients MUST NOT issue ENABLE once they 1560 SELECT/EXAMINE a mailbox; however, server implementations don't have 1561 to check that no mailbox is selected or was previously selected 1562 during the duration of a connection. 1564 The ENABLE command can be issued multiple times in a session. It is 1565 additive; i.e., "ENABLE a b", followed by "ENABLE c" is the same as a 1566 single command "ENABLE a b c". When multiple ENABLE commands are 1567 issued, each corresponding ENABLED response SHOULD only contain 1568 extensions enabled by the corresponding ENABLE command, i.e. for the 1569 above example, the ENABLED response to "ENABLE c" should not contain 1570 "a" or "b". 1572 There are no limitations on pipelining ENABLE. For example, it is 1573 possible to send ENABLE and then immediately SELECT, or a LOGIN 1574 immediately followed by ENABLE. 1576 The server MUST NOT change the CAPABILITY list as a result of 1577 executing ENABLE; i.e., a CAPABILITY command issued right after an 1578 ENABLE command MUST list the same capabilities as a CAPABILITY 1579 command issued before the ENABLE command. This is demonstrated in 1580 the following example: 1582 C: t1 CAPABILITY 1583 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1584 S: t1 OK foo 1585 C: t2 ENABLE CONDSTORE X-GOOD-IDEA 1586 S: * ENABLED X-GOOD-IDEA 1587 S: t2 OK foo 1588 C: t3 CAPABILITY 1589 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1590 S: t3 OK foo again 1592 In the following example, the client enables CONDSTORE: 1594 C: a1 ENABLE CONDSTORE 1595 S: * ENABLED CONDSTORE 1596 S: a1 OK Conditional Store enabled 1598 6.3.1.1. Note to Designers of Extensions That May Use the ENABLE 1599 Command 1601 Designers of IMAP extensions are discouraged from creating extensions 1602 that require ENABLE unless there is no good alternative design. 1603 Specifically, extensions that cause potentially incompatible behavior 1604 changes to deployed server responses (and thus benefit from ENABLE) 1605 have a higher complexity cost than extensions that do not. 1607 6.3.2. SELECT Command 1609 Arguments: mailbox name 1611 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1612 REQUIRED OK untagged responses: PERMANENTFLAGS, 1613 UIDNEXT, UIDVALIDITY 1614 REQUIRED untagged response: LIST 1616 Result: OK - select completed, now in selected state 1617 NO - select failure, now in authenticated state: no 1618 such mailbox, can't access mailbox 1619 BAD - command unknown or arguments invalid 1621 The SELECT command selects a mailbox so that messages in the mailbox 1622 can be accessed. Before returning an OK to the client, the server 1623 MUST send the following untagged data to the client. (The order of 1624 individual responses is not important.) Note that earlier versions 1625 of this protocol (e.g. IMAP2bis) only required the FLAGS and EXISTS 1626 untagged data; consequently, client implementations SHOULD implement 1627 default behavior for missing data as discussed with the individual 1628 item. 1630 FLAGS Defined flags in the mailbox. See the description of the 1631 FLAGS response for more detail. 1633 EXISTS The number of messages in the mailbox. See the 1634 description of the EXISTS response for more detail. 1636 LIST The server MUST return a LIST response with the mailbox name. 1637 If the server allows de-normalized UTF-8 mailbox names (see 1638 Section 5.1) and the supplied mailbox name differs from the 1639 normalized version, the server MUST return LIST with the OLDNAME 1640 extended data item. See Section 6.3.9.7 for more details. 1642 OK [PERMANENTFLAGS ()] A list of message flags that 1643 the client can change permanently. If this is missing, the client 1644 should assume that all flags can be changed permanently. 1646 OK [UIDNEXT ] The next unique identifier value. Refer to 1647 Section 2.3.1.1 for more information. 1649 OK [UIDVALIDITY ] The unique identifier validity value. Refer to 1650 Section 2.3.1.1 for more information. 1652 Only one mailbox can be selected at a time in a connection; 1653 simultaneous access to multiple mailboxes requires multiple 1654 connections. The SELECT command automatically deselects any 1655 currently selected mailbox before attempting the new selection. 1656 Consequently, if a mailbox is selected and a SELECT command that 1657 fails is attempted, no mailbox is selected. When deselecting a 1658 selected mailbox, the server MUST return an untagged OK response with 1659 the "[CLOSED]" response code when the currently selected mailbox is 1660 closed (see Paragraph 10). 1662 If the client is permitted to modify the mailbox, the server SHOULD 1663 prefix the text of the tagged OK response with the "[READ-WRITE]" 1664 response code. 1666 If the client is not permitted to modify the mailbox but is permitted 1667 read access, the mailbox is selected as read-only, and the server 1668 MUST prefix the text of the tagged OK response to SELECT with the 1669 "[READ-ONLY]" response code. Read-only access through SELECT differs 1670 from the EXAMINE command in that certain read-only mailboxes MAY 1671 permit the change of permanent state on a per-user (as opposed to 1672 global) basis. Netnews messages marked in a server-based .newsrc 1673 file are an example of such per-user permanent state that can be 1674 modified with read-only mailboxes. 1676 Example: C: A142 SELECT INBOX 1677 S: * 172 EXISTS 1678 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1679 S: * OK [UIDNEXT 4392] Predicted next UID 1680 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1681 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1682 S: * LIST () "/" INBOX 1683 S: A142 OK [READ-WRITE] SELECT completed 1685 Example: C: A142 SELECT INBOX 1686 S: * 172 EXISTS 1687 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1688 S: * OK [UIDNEXT 4392] Predicted next UID 1689 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1690 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1691 S: A142 OK [READ-WRITE] SELECT completed 1692 [...some time later...] 1693 C: A143 SELECT Drafts 1694 S: * OK [CLOSED] Previous mailbox is now closed 1695 S: * 5 EXISTS 1696 S: * OK [UIDVALIDITY 9877410381] UIDs valid 1697 S: * OK [UIDNEXT 102] Predicted next UID 1698 S: * LIST () "/" Drafts 1699 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1700 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Answered 1701 \Flagged \Draft \*)] System flags and keywords allowed 1702 S: A143 OK [READ-WRITE] SELECT completed 1704 Note that IMAP4rev1 compliant servers can also send the untagged 1705 RECENT response which was deprecated in IMAP4rev2. E.g. "* 0 1706 RECENT". Pure IMAP4rev2 clients are advised to ignore the untagged 1707 RECENT response. 1709 6.3.3. EXAMINE Command 1711 Arguments: mailbox name 1713 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1714 REQUIRED OK untagged responses: PERMANENTFLAGS, 1715 UIDNEXT, UIDVALIDITY 1716 REQUIRED untagged response: LIST 1718 Result: OK - examine completed, now in selected state 1719 NO - examine failure, now in authenticated state: no 1720 such mailbox, can't access mailbox BAD - command unknown 1721 or arguments invalid 1723 The EXAMINE command is identical to SELECT and returns the same 1724 output; however, the selected mailbox is identified as read-only. No 1725 changes to the permanent state of the mailbox, including per-user 1726 state, are permitted. 1728 The text of the tagged OK response to the EXAMINE command MUST begin 1729 with the "[READ-ONLY]" response code. 1731 Example: C: A932 EXAMINE blurdybloop 1732 S: * 17 EXISTS 1733 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1734 S: * OK [UIDNEXT 4392] Predicted next UID 1735 S: * LIST () "/" blurdybloop 1736 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1737 S: * OK [PERMANENTFLAGS ()] No permanent flags permitted 1738 S: A932 OK [READ-ONLY] EXAMINE completed 1740 6.3.4. CREATE Command 1742 Arguments: mailbox name 1744 Responses: OPTIONAL untagged response: LIST 1746 Result: OK - create completed 1747 NO - create failure: can't create mailbox with that name 1748 BAD - command unknown or arguments invalid 1750 The CREATE command creates a mailbox with the given name. An OK 1751 response is returned only if a new mailbox with that name has been 1752 created. It is an error to attempt to create INBOX or a mailbox with 1753 a name that refers to an extant mailbox. Any error in creation will 1754 return a tagged NO response. If a client attempts to create a UTF-8 1755 mailbox name that is not a valid Net-Unicode name, the server MUST 1756 reject the creation or convert the name to Net-Unicode prior to 1757 creating the mailbox. If the server decides to convert (normalize) 1758 the name, it SHOULD return an untagged LIST with OLDNAME extended 1759 data item, with the OLDNAME value being the supplied mailbox name and 1760 the name parameter being the normalized mailbox name. (See 1761 Section 6.3.9.7 for more details.) 1763 Mailboxes created in one IMAP session MAY be announced to other IMAP 1764 sessions using unsolicited LIST response. If the server 1765 automatically subscribes a mailbox when it is created, then the 1766 unsolicited LIST response for each affected subscribed mailbox name 1767 MUST include the \Subscribed attribute. 1769 If the mailbox name is suffixed with the server's hierarchy separator 1770 character (as returned from the server by a LIST command), this is a 1771 declaration that the client intends to create mailbox names under 1772 this name in the hierarchy. Server implementations that do not 1773 require this declaration MUST ignore the declaration. In any case, 1774 the name created is without the trailing hierarchy delimiter. 1776 If the server's hierarchy separator character appears elsewhere in 1777 the name, the server SHOULD create any superior hierarchical names 1778 that are needed for the CREATE command to be successfully completed. 1779 In other words, an attempt to create "foo/bar/zap" on a server in 1780 which "/" is the hierarchy separator character SHOULD create foo/ and 1781 foo/bar/ if they do not already exist. 1783 If a new mailbox is created with the same name as a mailbox which was 1784 deleted, its unique identifiers MUST be greater than any unique 1785 identifiers used in the previous incarnation of the mailbox UNLESS 1786 the new incarnation has a different unique identifier validity value. 1787 See the description of the UID command for more detail. 1789 Example: C: A003 CREATE owatagusiam/ 1790 S: A003 OK CREATE completed 1791 C: A004 CREATE owatagusiam/blurdybloop 1792 S: A004 OK CREATE completed 1793 C: A005 CREATE NonNormalized 1794 S: * LIST () "/" "Normalized" ("OLDNAME" ("NonNormalized")) 1795 S: A005 OK CREATE completed 1797 (in the last example imagine that "NonNormalized" is 1798 a non NFC normalized Unicode mailbox name and that 1799 "Normalized" is its NFC normalized version.) 1801 Note: The interpretation of this example depends on whether "/" 1802 was returned as the hierarchy separator from LIST. If "/" is the 1803 hierarchy separator, a new level of hierarchy named "owatagusiam" 1804 with a member called "blurdybloop" is created. Otherwise, two 1805 mailboxes at the same hierarchy level are created. 1807 6.3.5. DELETE Command 1809 Arguments: mailbox name 1811 Responses: OPTIONAL untagged response: LIST 1813 Result: OK - delete completed 1814 NO - delete failure: can't delete mailbox with that name 1815 BAD - command unknown or arguments invalid 1817 The DELETE command permanently removes the mailbox with the given 1818 name. A tagged OK response is returned only if the mailbox has been 1819 deleted. It is an error to attempt to delete INBOX or a mailbox name 1820 that does not exist. 1822 The DELETE command MUST NOT remove inferior hierarchical names. For 1823 example, if a mailbox "foo" has an inferior "foo.bar" (assuming "." 1824 is the hierarchy delimiter character), removing "foo" MUST NOT remove 1825 "foo.bar". It is an error to attempt to delete a name that has 1826 inferior hierarchical names and also has the \Noselect mailbox name 1827 attribute (see the description of the LIST response for more 1828 details). 1830 It is permitted to delete a name that has inferior hierarchical names 1831 and does not have the \Noselect mailbox name attribute. If the 1832 server implementation does not permit deleting the name while 1833 inferior hierarchical names exists then it SHOULD disallow the DELETE 1834 command by returning a tagged NO response. The NO response SHOULD 1835 include the HASCHILDREN response code. Alternatively the server MAY 1836 allow the DELETE command, but sets the \Noselect mailbox name 1837 attribute for that name. 1839 If the server returns OK response, all messages in that mailbox are 1840 removed by the DELETE command. 1842 The value of the highest-used unique identifier of the deleted 1843 mailbox MUST be preserved so that a new mailbox created with the same 1844 name will not reuse the identifiers of the former incarnation, UNLESS 1845 the new incarnation has a different unique identifier validity value. 1846 See the description of the UID command for more detail. 1848 If the server decides to convert (normalize) the mailbox name, it 1849 SHOULD return an untagged LIST with the "\NonExistent" attribute and 1850 OLDNAME extended data item, with the OLDNAME value being the supplied 1851 mailbox name and the name parameter being the normalized mailbox 1852 name. (See Section 6.3.9.7 for more details.) 1854 Mailboxes deleted in one IMAP session MAY be announced to other IMAP 1855 sessions using unsolicited LIST response, containing the 1856 "\NonExistent" attribute. 1858 Examples: C: A682 LIST "" * 1859 S: * LIST () "/" blurdybloop 1860 S: * LIST (\Noselect) "/" foo 1861 S: * LIST () "/" foo/bar 1862 S: A682 OK LIST completed 1863 C: A683 DELETE blurdybloop 1864 S: A683 OK DELETE completed 1865 C: A684 DELETE foo 1866 S: A684 NO Name "foo" has inferior hierarchical names 1867 C: A685 DELETE foo/bar 1868 S: A685 OK DELETE Completed 1869 C: A686 LIST "" * 1870 S: * LIST (\Noselect) "/" foo 1871 S: A686 OK LIST completed 1872 C: A687 DELETE foo 1873 S: A687 OK DELETE Completed 1874 C: A82 LIST "" * 1875 S: * LIST () "." blurdybloop 1876 S: * LIST () "." foo 1877 S: * LIST () "." foo.bar 1878 S: A82 OK LIST completed 1879 C: A83 DELETE blurdybloop 1880 S: A83 OK DELETE completed 1881 C: A84 DELETE foo 1882 S: A84 OK DELETE Completed 1883 C: A85 LIST "" * 1884 S: * LIST () "." foo.bar 1885 S: A85 OK LIST completed 1886 C: A86 LIST "" % 1887 S: * LIST (\Noselect) "." foo 1888 S: A86 OK LIST completed 1890 6.3.6. RENAME Command 1892 Arguments: existing mailbox name 1893 new mailbox name 1895 Responses: OPTIONAL untagged response: LIST 1897 Result: OK - rename completed 1898 NO - rename failure: can't rename mailbox with that name, 1899 can't rename to mailbox with that name 1900 BAD - command unknown or arguments invalid 1902 The RENAME command changes the name of a mailbox. A tagged OK 1903 response is returned only if the mailbox has been renamed. It is an 1904 error to attempt to rename from a mailbox name that does not exist or 1905 to a mailbox name that already exists. Any error in renaming will 1906 return a tagged NO response. 1908 If the name has inferior hierarchical names, then the inferior 1909 hierarchical names MUST also be renamed. For example, a rename of 1910 "foo" to "zap" will rename "foo/bar" (assuming "/" is the hierarchy 1911 delimiter character) to "zap/bar". 1913 If the server's hierarchy separator character appears in the name, 1914 the server SHOULD create any superior hierarchical names that are 1915 needed for the RENAME command to complete successfully. In other 1916 words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a 1917 server in which "/" is the hierarchy separator character in the 1918 corresponding namespace SHOULD create baz/ and baz/rag/ if they do 1919 not already exist. 1921 The value of the highest-used unique identifier of the old mailbox 1922 name MUST be preserved so that a new mailbox created with the same 1923 name will not reuse the identifiers of the former incarnation, UNLESS 1924 the new incarnation has a different unique identifier validity value. 1925 See the description of the UID command for more detail. 1927 Renaming INBOX is permitted, and has special behavior. (Note that 1928 some servers disallow renaming INBOX, so clients need to be able to 1929 handle such RENAME failing). It moves all messages in INBOX to a new 1930 mailbox with the given name, leaving INBOX empty. If the server 1931 implementation supports inferior hierarchical names of INBOX, these 1932 are unaffected by a rename of INBOX. 1934 If the server allows creation of mailboxes with names that are not 1935 valid Net-Unicode names, the server normalizes both the existing 1936 mailbox name parameter and the new mailbox name parameter. If the 1937 normalized version of any of these 2 parameters differs from the 1938 corresponding supplied version, the server SHOULD return an untagged 1939 LIST response with OLDNAME extended data item, with the OLDNAME value 1940 being the supplied existing mailbox name and the name parameter being 1941 the normalized new mailbox name (see Section 6.3.9.7). This would 1942 allow the client to correlate supplied name with the normalized name. 1944 Mailboxes renamed in one IMAP session MAY be announced to other IMAP 1945 sessions using unsolicited LIST response with OLDNAME extended data 1946 item. 1948 In both of the above cases: if the server automatically subscribes a 1949 mailbox when it is renamed, then the unsolicited LIST response for 1950 each affected subscribed mailbox name MUST include the \Subscribed 1951 attribute. No unsolicited LIST responses need to be sent for 1952 children mailboxes, if any. When INBOX is successfully renamed, a 1953 new INBOX is assumed to be created. No unsolicited LIST responses 1954 need to be sent for INBOX in this case. 1956 Examples: C: A682 LIST "" * 1957 S: * LIST () "/" blurdybloop 1958 S: * LIST (\Noselect) "/" foo 1959 S: * LIST () "/" foo/bar 1960 S: A682 OK LIST completed 1961 C: A683 RENAME blurdybloop sarasoop 1962 S: A683 OK RENAME completed 1963 C: A684 RENAME foo zowie 1964 S: A684 OK RENAME Completed 1965 C: A685 LIST "" * 1966 S: * LIST () "/" sarasoop 1967 S: * LIST (\Noselect) "/" zowie 1968 S: * LIST () "/" zowie/bar 1969 S: A685 OK LIST completed 1971 C: Z432 LIST "" * 1972 S: * LIST () "." INBOX 1973 S: * LIST () "." INBOX.bar 1974 S: Z432 OK LIST completed 1975 C: Z433 RENAME INBOX old-mail 1976 S: Z433 OK RENAME completed 1977 C: Z434 LIST "" * 1978 S: * LIST () "." INBOX 1979 S: * LIST () "." INBOX.bar 1980 S: * LIST () "." old-mail 1981 S: Z434 OK LIST completed 1983 Note that renaming a mailbox doesn't update subscription information 1984 on the original name. To keep subscription information in sync, the 1985 following sequence of commands can be used: 1987 C: 1001 RENAME X Y 1988 C: 1002 SUBSCRIBE Y 1989 C: 1003 UNSUBSCRIBE X 1991 Note that the above sequence of commands doesn't account for updating 1992 subscription for any children mailboxes of mailbox X. 1994 6.3.7. SUBSCRIBE Command 1996 Arguments: mailbox 1998 Responses: no specific responses for this command 2000 Result: OK - subscribe completed 2001 NO - subscribe failure: can't subscribe to that name 2002 BAD - command unknown or arguments invalid 2004 The SUBSCRIBE command adds the specified mailbox name to the server's 2005 set of "active" or "subscribed" mailboxes as returned by the LIST 2006 (SUBSCRIBED) command. This command returns a tagged OK response if 2007 the subscription is successful or if the mailbox is already 2008 subscribed. 2010 A server MAY validate the mailbox argument to SUBSCRIBE to verify 2011 that it exists. However, it SHOULD NOT unilaterally remove an 2012 existing mailbox name from the subscription list even if a mailbox by 2013 that name no longer exists. 2015 Note: This requirement is because a server site can choose to 2016 routinely remove a mailbox with a well-known name (e.g., "system- 2017 alerts") after its contents expire, with the intention of 2018 recreating it when new contents are appropriate. 2020 Example: C: A002 SUBSCRIBE #news.comp.mail.mime 2021 S: A002 OK SUBSCRIBE completed 2023 6.3.8. UNSUBSCRIBE Command 2025 Arguments: mailbox name 2027 Responses: no specific responses for this command 2029 Result: OK - unsubscribe completed 2030 NO - unsubscribe failure: can't unsubscribe that name 2031 BAD - command unknown or arguments invalid 2033 The UNSUBSCRIBE command removes the specified mailbox name from the 2034 server's set of "active" or "subscribed" mailboxes as returned by the 2035 LIST (SUBSCRIBED) command. This command returns a tagged OK response 2036 if the unsubscription is successful or if the mailbox is not 2037 subscribed. 2039 Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime 2040 S: A002 OK UNSUBSCRIBE completed 2042 6.3.9. LIST Command 2044 Arguments (basic): reference name 2045 mailbox name with possible wildcards 2047 Arguments (extended): selection options (OPTIONAL) 2048 reference name 2049 mailbox patterns 2050 return options (OPTIONAL) 2052 Responses: untagged responses: LIST 2054 Result: OK - list completed 2055 NO - list failure: can't list that reference or name 2056 BAD - command unknown or arguments invalid 2058 The LIST command returns a subset of names from the complete set of 2059 all names available to the client. Zero or more untagged LIST 2060 replies are returned, containing the name attributes, hierarchy 2061 delimiter, name, and possible extension information; see the 2062 description of the LIST reply for more detail. 2064 The LIST command SHOULD return its data quickly, without undue delay. 2065 For example, it SHOULD NOT go to excess trouble to calculate the 2066 \Marked or \Unmarked status or perform other processing; if each name 2067 requires 1 second of processing, then a list of 1200 names would take 2068 20 minutes! 2070 The extended LIST command, originally introduced in [RFC5258], 2071 provides capabilities beyond that of the original IMAP LIST command. 2072 The extended syntax is being used if one or more of the following 2073 conditions is true: 2075 1. if the first word after the command name begins with a 2076 parenthesis ("LIST selection options"); 2078 2. if the second word after the command name begins with a 2079 parenthesis; 2081 3. if the LIST command has more than 2 parameters ("LIST return 2082 options") 2084 An empty ("" string) reference name argument indicates that the 2085 mailbox name is interpreted as by SELECT. The returned mailbox names 2086 MUST match the supplied mailbox name pattern(s). A non-empty 2087 reference name argument is the name of a mailbox or a level of 2088 mailbox hierarchy, and indicates the context in which the mailbox 2089 name is interpreted. Clients SHOULD use the empty reference 2090 argument. 2092 In the basic syntax only, an empty ("" string) mailbox name argument 2093 is a special request to return the hierarchy delimiter and the root 2094 name of the name given in the reference. The value returned as the 2095 root MAY be the empty string if the reference is non-rooted or is an 2096 empty string. In all cases, a hierarchy delimiter (or NIL if there 2097 is no hierarchy) is returned. This permits a client to get the 2098 hierarchy delimiter (or find out that the mailbox names are flat) 2099 even when no mailboxes by that name currently exist. 2101 In the extended syntax, any mailbox name arguments that are empty 2102 strings are ignored. There is no special meaning for empty mailbox 2103 names when the extended syntax is used. 2105 The reference and mailbox name arguments are interpreted into a 2106 canonical form that represents an unambiguous left-to-right 2107 hierarchy. The returned mailbox names will be in the interpreted 2108 form, that we call "canonical LIST pattern" later in this document. 2109 To define the term "canonical LIST pattern" formally: it refers to 2110 the canonical pattern constructed internally by the server from the 2111 reference and mailbox name arguments. 2113 Note: The interpretation of the reference argument is 2114 implementation-defined. It depends upon whether the server 2115 implementation has a concept of the "current working directory" 2116 and leading "break out characters", which override the current 2117 working directory. 2119 For example, on a server which exports a UNIX or NT filesystem, 2120 the reference argument contains the current working directory, and 2121 the mailbox name argument would contain the name as interpreted in 2122 the current working directory. 2124 If a server implementation has no concept of break out characters, 2125 the canonical form is normally the reference name appended with 2126 the mailbox name. Note that if the server implements the 2127 namespace convention (Section 5.1.2.1), "#" is a break out 2128 character and must be treated as such. 2130 If the reference argument is not a level of mailbox hierarchy 2131 (that is, it is a \NoInferiors name), and/or the reference 2132 argument does not end with the hierarchy delimiter, it is 2133 implementation-dependent how this is interpreted. For example, a 2134 reference of "foo/bar" and mailbox name of "rag/baz" could be 2135 interpreted as "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/ 2136 baz". A client SHOULD NOT use such a reference argument except at 2137 the explicit request of the user. A hierarchical browser MUST NOT 2138 make any assumptions about server interpretation of the reference 2139 unless the reference is a level of mailbox hierarchy AND ends with 2140 the hierarchy delimiter. 2142 Any part of the reference argument that is included in the 2143 interpreted form SHOULD prefix the interpreted form. It SHOULD also 2144 be in the same form as the reference name argument. This rule 2145 permits the client to determine if the returned mailbox name is in 2146 the context of the reference argument, or if something about the 2147 mailbox argument overrode the reference argument. Without this rule, 2148 the client would have to have knowledge of the server's naming 2149 semantics including what characters are "breakouts" that override a 2150 naming context. 2152 For example, here are some examples of how references 2153 and mailbox names might be interpreted on a UNIX-based 2154 server: 2156 Reference Mailbox Name Interpretation 2157 ------------ ------------ -------------- 2158 ~smith/Mail/ foo.* ~smith/Mail/foo.* 2159 archive/ % archive/% 2160 #news. comp.mail.* #news.comp.mail.* 2161 ~smith/Mail/ /usr/doc/foo /usr/doc/foo 2162 archive/ ~fred/Mail/* ~fred/Mail/* 2164 The first three examples demonstrate interpretations in 2165 the context of the reference argument. Note that 2166 "~smith/Mail" SHOULD NOT be transformed into something 2167 like "/u2/users/smith/Mail", or it would be impossible 2168 for the client to determine that the interpretation was 2169 in the context of the reference. 2171 The character "*" is a wildcard, and matches zero or more characters 2172 at this position. The character "%" is similar to "*", but it does 2173 not match a hierarchy delimiter. If the "%" wildcard is the last 2174 character of a mailbox name argument, matching levels of hierarchy 2175 are also returned. If these levels of hierarchy are not also 2176 selectable mailboxes, they are returned with the \Noselect mailbox 2177 name attribute (see the description of the LIST response for more 2178 details). 2180 Any syntactically valid pattern that is not accepted by a server for 2181 any reason MUST be silently ignored. I.e. it results in no LIST 2182 responses and the LIST command still returns tagged OK response. 2184 Selection options tell the server to limit the mailbox names that are 2185 selected by the LIST operation. If selection options are used, the 2186 mailboxes returned are those that match both the list of canonical 2187 LIST patterns and the selection options. Unless a particular 2188 selection option provides special rules, the selection options are 2189 cumulative: a mailbox that matches the mailbox patterns is selected 2190 only if it also matches all of the selection options. (An example of 2191 a selection option with special rules is the RECURSIVEMATCH option.) 2192 Return options control what information is returned for each matched 2193 mailbox. Return options MUST NOT cause the server to report 2194 information about additional mailbox names other than those that 2195 match the canonical LIST patterns and selection options. If no 2196 return options are specified, the client is only expecting 2197 information about mailbox attributes. The server MAY return other 2198 information about the matched mailboxes, and clients MUST be able to 2199 handle that situation. 2201 Initial selection options and return options are defined in the 2202 following subsections, and new ones will also be defined in 2203 extensions. Initial options defined in this document MUST be 2204 supported. Each non-initial option will be enabled by a capability 2205 string (one capability may enable multiple options), and a client 2206 MUST NOT send an option for which the server has not advertised 2207 support. A server MUST respond to options it does not recognize with 2208 a BAD response. The client SHOULD NOT specify any option more than 2209 once; however, if the client does this, the server MUST act as if it 2210 received the option only once. The order in which options are 2211 specified by the client is not significant. 2213 In general, each selection option except RECURSIVEMATCH will have a 2214 corresponding return option with the same name. The REMOTE selection 2215 option is an anomaly in this regard, and does not have a 2216 corresponding return option. That is because it expands, rather than 2217 restricts, the set of mailboxes that are returned. Future extensions 2218 to this specification should keep this parallelism in mind and define 2219 a pair of corresponding selection and return options. 2221 Server implementations are permitted to "hide" otherwise accessible 2222 mailboxes from the wildcard characters, by preventing certain 2223 characters or names from matching a wildcard in certain situations. 2224 For example, a UNIX-based server might restrict the interpretation of 2225 "*" so that an initial "/" character does not match. 2227 The special name INBOX is included in the output from LIST, if INBOX 2228 is supported by this server for this user and if the uppercase string 2229 "INBOX" matches the interpreted reference and mailbox name arguments 2230 with wildcards as described above. The criteria for omitting INBOX 2231 is whether SELECT INBOX will return failure; it is not relevant 2232 whether the user's real INBOX resides on this or some other server. 2234 6.3.9.1. LIST Selection Options 2236 The selection options defined in this specification are as follows: 2238 SUBSCRIBED - causes the LIST command to list subscribed names, 2239 rather than the existing mailboxes. This will often be a subset 2240 of the actual mailboxes. It's also possible for this list to 2241 contain the names of mailboxes that don't exist. In any case, the 2242 list MUST include exactly those mailbox names that match the 2243 canonical list pattern and are subscribed to. 2245 This option defines a mailbox attribute, "\Subscribed", that 2246 indicates that a mailbox name is subscribed to. The "\Subscribed" 2247 attribute MUST be supported and MUST be accurately computed when 2248 the SUBSCRIBED selection option is specified. 2250 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 2251 return option (see below). 2253 REMOTE - causes the LIST command to show remote mailboxes as well as 2254 local ones, as described in [RFC2193]. This option is intended to 2255 replace the RLIST command and, in conjunction with the SUBSCRIBED 2256 selection option, the RLSUB command. Servers that don't support 2257 remote mailboxes just ignore this option. 2259 This option defines a mailbox attribute, "\Remote", that indicates 2260 that a mailbox is a remote mailbox. The "\Remote" attribute MUST 2261 be accurately computed when the REMOTE option is specified. 2263 The REMOTE selection option has no interaction with other options. 2264 Its effect is to tell the server to apply the other options, if 2265 any, to remote mailboxes, in addition to local ones. In 2266 particular, it has no interaction with RECURSIVEMATCH (see below). 2267 A request for (REMOTE RECURSIVEMATCH) is invalid, because a 2268 request for (RECURSIVEMATCH) is also invalid. A request for 2269 (REMOTE RECURSIVEMATCH SUBSCRIBED) is asking for all subscribed 2270 mailboxes, both local and remote. 2272 RECURSIVEMATCH - this option forces the server to return information 2273 about parent mailboxes that don't match other selection options, 2274 but have some submailboxes that do. Information about children is 2275 returned in the CHILDINFO extended data item, as described in 2276 Section 6.3.9.6. 2278 Note 1: In order for a parent mailbox to be returned, it still has 2279 to match the canonical LIST pattern. 2281 Note 2: When returning the CHILDINFO extended data item, it 2282 doesn't matter whether or not the submailbox matches the canonical 2283 LIST pattern. See also example 9 in Section 6.3.9.8. 2285 The RECURSIVEMATCH option MUST NOT occur as the only selection 2286 option (or only with REMOTE), as it only makes sense when other 2287 selection options are also used. The server MUST return BAD 2288 tagged response in such case. 2290 Note that even if the RECURSIVEMATCH option is specified, the 2291 client MUST still be able to handle a case when a CHILDINFO 2292 extended data item is returned and there are no submailboxes that 2293 meet the selection criteria of the subsequent LIST command, as 2294 they can be deleted/renamed after the LIST response was sent, but 2295 before the client had a chance to access them. 2297 6.3.9.2. LIST Return Options 2299 The return options defined in this specification are as follows: 2301 SUBSCRIBED - causes the LIST command to return subscription state 2302 for all matching mailbox names. The "\Subscribed" attribute MUST 2303 be supported and MUST be accurately computed when the SUBSCRIBED 2304 return option is specified. Further, all mailbox flags MUST be 2305 accurately computed (this differs from the behavior of the 2306 obsolete LSUB command from IMAP4rev1). 2308 CHILDREN - requests mailbox child information as originally proposed 2309 in [RFC3348]. See Section 6.3.9.5, below, for details. This 2310 option MUST be supported by all servers. 2312 STATUS - requests STATUS response for each matching mailbox. 2314 This option takes STATUS data items as parameters. For each 2315 selectable mailbox matching the list pattern and selection 2316 options, the server MUST return an untagged LIST response 2317 followed by an untagged STATUS response containing the 2318 information requested in the STATUS return option, except for 2319 some cases described below. 2321 If an attempted STATUS for a listed mailbox fails because the 2322 mailbox can't be selected (e.g., if the "l" ACL right [RFC4314] 2323 is granted to the mailbox and the "r" right is not granted, or 2324 due to a race condition between LIST and STATUS changing the 2325 mailbox to \NoSelect), the STATUS response MUST NOT be returned 2326 and the LIST response MUST include the \NoSelect attribute. 2327 This means the server may have to buffer the LIST reply until 2328 it has successfully looked up the necessary STATUS information. 2330 If the server runs into unexpected problems while trying to 2331 look up the STATUS information, it MAY drop the corresponding 2332 STATUS reply. In such a situation, the LIST command would 2333 still return a tagged OK reply. 2335 6.3.9.3. General Principles for Returning LIST Responses 2337 This section outlines several principles that can be used by server 2338 implementations of this document to decide whether a LIST response 2339 should be returned, as well as how many responses and what kind of 2340 information they may contain. 2342 1. At most one LIST response should be returned for each mailbox 2343 name that matches the canonical LIST pattern. Server 2344 implementors must not assume that clients will be able to 2345 assemble mailbox attributes and other information returned in 2346 multiple LIST responses. 2348 2. There are only two reasons for including a matching mailbox name 2349 in the responses to the LIST command (note that the server is 2350 allowed to return unsolicited responses at any time, and such 2351 responses are not governed by this rule): 2353 A. The mailbox name also satisfies the selection criteria. 2355 B. The mailbox name doesn't satisfy the selection criteria, but 2356 it has at least one descendant mailbox name that satisfies 2357 the selection criteria and that doesn't match the canonical 2358 LIST pattern. 2360 For more information on this case, see the CHILDINFO extended 2361 data item described in Section 6.3.9.6. Note that the 2362 CHILDINFO extended data item can only be returned when the 2363 RECURSIVEMATCH selection option is specified. 2365 3. Attributes returned in the same LIST response must be treated 2366 additively. For example, the following response 2368 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2370 means that the "Fruit/Peach" mailbox doesn't exist, but it is 2371 subscribed. 2373 6.3.9.4. Additional LIST-related Requirements on Clients 2375 All clients MUST treat a LIST attribute with a stronger meaning as 2376 implying any attribute that can be inferred from it. (See 2377 Section 7.2.3 for the list of currently defined attributes). For 2378 example, the client must treat the presence of the \NoInferiors 2379 attribute as if the \HasNoChildren attribute was also sent by the 2380 server. 2382 The following table summarizes inference rules. 2384 +--------------------+-------------------+ 2385 | returned attribute | implied attribute | 2386 +--------------------+-------------------+ 2387 | \NoInferiors | \HasNoChildren | 2388 | \NonExistent | \NoSelect | 2389 +--------------------+-------------------+ 2391 6.3.9.5. The CHILDREN Return Option 2393 The CHILDREN return option is simply an indication that the client 2394 wants information about whether or not mailboxes contain children 2395 mailboxes; a server MAY provide it even if the option is not 2396 specified. 2398 Many IMAP4 clients present to the user a hierarchical view of the 2399 mailboxes that a user has access to. Rather than initially 2400 presenting to the user the entire mailbox hierarchy, it is often 2401 preferable to show to the user a collapsed outline list of the 2402 mailbox hierarchy (particularly if there is a large number of 2403 mailboxes). The user can then expand the collapsed outline hierarchy 2404 as needed. It is common to include within the collapsed hierarchy a 2405 visual clue (such as a ''+'') to indicate that there are child 2406 mailboxes under a particular mailbox. When the visual clue is 2407 clicked, the hierarchy list is expanded to show the child mailboxes. 2408 The CHILDREN return option provides a mechanism for a client to 2409 efficiently determine whether a particular mailbox has children, 2410 without issuing a LIST "" * or a LIST "" % for each mailbox name. 2411 The CHILDREN return option defines two new attributes that MUST be 2412 returned within a LIST response: \HasChildren and \HasNoChildren. 2413 Although these attributes MAY be returned in response to any LIST 2414 command, the CHILDREN return option is provided to indicate that the 2415 client particularly wants this information. If the CHILDREN return 2416 option is present, the server MUST return these attributes even if 2417 their computation is expensive. 2419 \HasChildren 2421 The presence of this attribute indicates that the mailbox has 2422 child mailboxes. A server SHOULD NOT set this attribute if 2423 there are child mailboxes and the user does not have permission 2424 to access any of them. In this case, \HasNoChildren SHOULD be 2425 used. In many cases, however, a server may not be able to 2426 efficiently compute whether a user has access to any child 2427 mailbox. Note that even though the \HasChildren attribute for a 2428 mailbox must be correct at the time of processing of the 2429 mailbox, a client must be prepared to deal with a situation when 2430 a mailbox is marked with the \HasChildren attribute, but no 2431 child mailbox appears in the response to the LIST command. This 2432 might happen, for example, due to children mailboxes being 2433 deleted or made inaccessible to the user (using access control) 2434 by another client before the server is able to list them. 2436 \HasNoChildren 2438 The presence of this attribute indicates that the mailbox has NO 2439 child mailboxes that are accessible to the currently 2440 authenticated user. 2442 It is an error for the server to return both a \HasChildren and a 2443 \HasNoChildren attribute in the same LIST response. 2445 Note: the \HasNoChildren attribute should not be confused with the 2446 the \NoInferiors attribute, which indicates that no child mailboxes 2447 exist now and none can be created in the future. 2449 6.3.9.6. CHILDINFO Extended Data Item 2451 The CHILDINFO extended data item MUST NOT be returned unless the 2452 client has specified the RECURSIVEMATCH selection option. 2454 The CHILDINFO extended data item in a LIST response describes the 2455 selection criteria that has caused it to be returned and indicates 2456 that the mailbox has at least one descendant mailbox that matches the 2457 selection criteria. 2459 Note: Some servers allow for mailboxes to exist without requiring 2460 their parent to exist. For example, a mailbox "Customers/ABC" can 2461 exist while the mailbox "Customers" does not. As CHILDINFO extended 2462 data item is not allowed if the RECURSIVEMATCH selection option is 2463 not specified, such servers SHOULD use the "\NonExistent 2464 \HasChildren" attribute pair to signal to the client that there is a 2465 descendant mailbox that matches the selection criteria. See example 2466 11 in Section 6.3.9.8. 2468 The returned selection criteria allow the client to distinguish a 2469 solicited response from an unsolicited one, as well as to distinguish 2470 among solicited responses caused by multiple pipelined LIST commands 2471 that specify different criteria. 2473 Servers SHOULD ONLY return a non-matching mailbox name along with 2474 CHILDINFO if at least one matching child is not also being returned. 2475 That is, servers SHOULD suppress redundant CHILDINFO responses. 2477 Examples 8 and 10 in Section 6.3.9.8 demonstrate the difference 2478 between present CHILDINFO extended data item and the "\HasChildren" 2479 attribute. 2481 The following table summarizes interaction between the "\NonExistent" 2482 attribute and CHILDINFO (the first column indicates whether the 2483 parent mailbox exists): 2485 +--------+-------------+------------------+-------------------------+ 2486 | exists | meets the | has a child that | returned | 2487 | | selection | meets the | IMAP4rev2/LIST-EXTENDED | 2488 | | criteria | selection | attributes and | 2489 | | | criteria | CHILDINFO | 2490 +--------+-------------+------------------+-------------------------+ 2491 | no | no | no | no LIST response | 2492 | | | | returned | 2493 | yes | no | no | no LIST response | 2494 | | | | returned | 2495 | no | yes | no | (\NonExistent ) | 2496 | yes | yes | no | () | 2497 | no | no | yes | (\NonExistent) + | 2498 | | | | CHILDINFO | 2499 | yes | no | yes | () + CHILDINFO | 2500 | no | yes | yes | (\NonExistent ) + | 2501 | | | | CHILDINFO | 2502 | yes | yes | yes | () + CHILDINFO | 2503 +--------+-------------+------------------+-------------------------+ 2505 where is one or more attributes that correspond to the 2506 selection criteria; for example, for the SUBSCRIBED option the 2507 is \Subscribed. 2509 6.3.9.7. OLDNAME Extended Data Item 2511 The OLDNAME extended data item is included when a mailbox name is 2512 created (with CREATE command), renamed (with RENAME command) or 2513 deleted (with DELETE command). (When a mailbox is deleted the 2514 "\NonExistent" attribute is also included.) IMAP extensions can 2515 specify other conditions when OLDNAME extended data item should be 2516 included. 2518 If the server allows de-normalized mailbox names (see Section 5.1) in 2519 SELECT/EXAMINE, CREATE, RENAME or DELETE, it SHOULD return an 2520 unsolicited LIST response that includes OLDNAME extended data item, 2521 whenever the supplied mailbox name differs from the resulting 2522 normalized mailbox name. From the client point of view this is 2523 indistinguishable from another user renaming of deleting the mailbox, 2524 as specified in the previous paragraph. 2526 A deleted mailbox can be announced like this: 2528 S: * LIST (\NonExistent) "." "INBOX.DeletedMailbox" 2530 Example of a renamed mailbox: 2532 S: * LIST () "/" "NewMailbox" ("OLDNAME" ("OldMailbox")) 2534 6.3.9.8. LIST Command Examples 2536 This example shows some uses of the basic LIST command: 2538 Example: C: A101 LIST "" "" 2539 S: * LIST (\Noselect) "/" "" 2540 S: A101 OK LIST Completed 2541 C: A102 LIST #news.comp.mail.misc "" 2542 S: * LIST (\Noselect) "." #news. 2543 S: A102 OK LIST Completed 2544 C: A103 LIST /usr/staff/jones "" 2545 S: * LIST (\Noselect) "/" / 2546 S: A103 OK LIST Completed 2547 C: A202 LIST ~/Mail/ % 2548 S: * LIST (\Noselect) "/" ~/Mail/foo 2549 S: * LIST () "/" ~/Mail/meetings 2550 S: A202 OK LIST completed 2552 Extended examples: 2554 1: The first example shows the complete local hierarchy that will 2555 be used for the other examples. 2557 C: A01 LIST "" "*" 2558 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2559 S: * LIST () "/" "Fruit" 2560 S: * LIST () "/" "Fruit/Apple" 2561 S: * LIST () "/" "Fruit/Banana" 2562 S: * LIST () "/" "Tofu" 2563 S: * LIST () "/" "Vegetable" 2564 S: * LIST () "/" "Vegetable/Broccoli" 2565 S: * LIST () "/" "Vegetable/Corn" 2566 S: A01 OK done 2568 2: In the next example, we will see the subscribed mailboxes. This 2569 is similar to, but not equivalent with now deprecated, (see [RFC3501] for more details on LSUB command). Note 2571 that the mailbox called "Fruit/Peach" is subscribed to, but does 2572 not actually exist (perhaps it was deleted while still 2573 subscribed). The "Fruit" mailbox is not subscribed to, but it 2574 has two subscribed children. The "Vegetable" mailbox is 2575 subscribed and has two children; one of them is subscribed as 2576 well. 2578 C: A02 LIST (SUBSCRIBED) "" "*" 2579 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2580 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2581 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2582 S: * LIST (\Subscribed) "/" "Vegetable" 2583 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2584 S: A02 OK done 2586 3: The next example shows the use of the CHILDREN option. The 2587 client, without having to list the second level of hierarchy, 2588 now knows which of the top-level mailboxes have submailboxes 2589 (children) and which do not. Note that it's not necessary for 2590 the server to return the \HasNoChildren attribute for the inbox, 2591 because the \NoInferiors attribute already implies that, and has 2592 a stronger meaning. 2594 C: A03 LIST () "" "%" RETURN (CHILDREN) 2595 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2596 S: * LIST (\HasChildren) "/" "Fruit" 2597 S: * LIST (\HasNoChildren) "/" "Tofu" 2598 S: * LIST (\HasChildren) "/" "Vegetable" 2599 S: A03 OK done 2601 4: In this example, we see more mailboxes that reside on another 2602 server. This is similar to the command . 2604 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 2605 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2606 S: * LIST (\HasChildren) "/" "Fruit" 2607 S: * LIST (\HasNoChildren) "/" "Tofu" 2608 S: * LIST (\HasChildren) "/" "Vegetable" 2609 S: * LIST (\Remote) "/" "Bread" 2610 S: * LIST (\HasChildren \Remote) "/" "Meat" 2611 S: A04 OK done 2613 5: The following example also requests the server to include 2614 mailboxes that reside on another server. The server returns 2615 information about all mailboxes that are subscribed. This is 2616 similar to the command (see [RFC2193] for more 2617 details on RLSUB). We also see the use of two selection 2618 options. 2620 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 2621 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2622 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2623 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2624 S: * LIST (\Subscribed) "/" "Vegetable" 2625 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2626 S: * LIST (\Remote \Subscribed) "/" "Bread" 2627 S: A05 OK done 2629 6: The following example requests the server to include mailboxes 2630 that reside on another server. The server is asked to return 2631 subscription information for all returned mailboxes. This is 2632 different from the example above. 2634 Note that the output of this command is not a superset of the 2635 output in the previous example, as it doesn't include LIST 2636 response for the non-existent "Fruit/Peach". 2638 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 2639 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2640 S: * LIST () "/" "Fruit" 2641 S: * LIST () "/" "Fruit/Apple" 2642 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2643 S: * LIST () "/" "Tofu" 2644 S: * LIST (\Subscribed) "/" "Vegetable" 2645 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2646 S: * LIST () "/" "Vegetable/Corn" 2647 S: * LIST (\Remote \Subscribed) "/" "Bread" 2648 S: * LIST (\Remote) "/" "Meat" 2649 S: A06 OK done 2651 7: The following example demonstrates the difference between the 2652 \HasChildren attribute and the CHILDINFO extended data item. 2654 Let's assume there is the following hierarchy: 2656 C: C01 LIST "" "*" 2657 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2658 S: * LIST () "/" "Foo" 2659 S: * LIST () "/" "Foo/Bar" 2660 S: * LIST () "/" "Foo/Baz" 2661 S: * LIST () "/" "Moo" 2662 S: C01 OK done 2664 If the client asks RETURN (CHILDREN), it will get this: 2666 C: CA3 LIST "" "%" RETURN (CHILDREN) 2667 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2668 S: * LIST (\HasChildren) "/" "Foo" 2669 S: * LIST (\HasNoChildren) "/" "Moo" 2670 S: CA3 OK done 2672 A) Let's also assume that the mailbox "Foo/Baz" is the only 2673 subscribed mailbox. Then we get this result: 2675 C: C02 LIST (SUBSCRIBED) "" "*" 2676 S: * LIST (\Subscribed) "/" "Foo/Baz" 2677 S: C02 OK done 2679 Now, if the client issues , the server 2680 will return no mailboxes (as the mailboxes "Moo", "Foo", and 2681 "Inbox" are NOT subscribed). However, if the client issues 2682 this: 2684 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2685 S: * LIST () "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2686 S: C04 OK done 2688 (i.e., the mailbox "Foo" is not subscribed, but it has a child 2689 that is.) 2691 A1) If the mailbox "Foo" had also been subscribed, the last 2692 command would return this: 2694 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2695 S: * LIST (\Subscribed) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2696 S: C04 OK done 2698 or even this: 2700 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2701 S: * LIST (\Subscribed \HasChildren) "/" "Foo" ("CHILDINFO" 2702 ("SUBSCRIBED")) 2703 S: C04 OK done 2705 A2) If we assume instead that the mailbox "Foo" is not part of 2706 the original hierarchy and is not subscribed, the last command 2707 will give this result: 2709 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2710 S: * LIST (\NonExistent) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2711 S: C04 OK done 2712 B) Now, let's assume that no mailbox is subscribed. In this 2713 case, the command will 2714 return no responses, as there are no subscribed children (even 2715 though "Foo" has children). 2717 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 2718 are subscribed. In that case, we see this result: 2720 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 2721 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 2722 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 2723 S: C04 OK done 2725 (which means that the mailbox "Foo" has children, but none of 2726 them is subscribed). 2728 8: The following example demonstrates that the CHILDINFO extended 2729 data item is returned whether or not children mailboxes match 2730 the canonical LIST pattern. 2732 Let's assume there is the following hierarchy: 2734 C: D01 LIST "" "*" 2735 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2736 S: * LIST () "/" "foo2" 2737 S: * LIST () "/" "foo2/bar1" 2738 S: * LIST () "/" "foo2/bar2" 2739 S: * LIST () "/" "baz2" 2740 S: * LIST () "/" "baz2/bar2" 2741 S: * LIST () "/" "baz2/bar22" 2742 S: * LIST () "/" "baz2/bar222" 2743 S: * LIST () "/" "eps2" 2744 S: * LIST () "/" "eps2/mamba" 2745 S: * LIST () "/" "qux2/bar2" 2746 S: D01 OK done 2748 And that the following mailboxes are subscribed: 2750 C: D02 LIST (SUBSCRIBED) "" "*" 2751 S: * LIST (\Subscribed) "/" "foo2/bar1" 2752 S: * LIST (\Subscribed) "/" "foo2/bar2" 2753 S: * LIST (\Subscribed) "/" "baz2/bar2" 2754 S: * LIST (\Subscribed) "/" "baz2/bar22" 2755 S: * LIST (\Subscribed) "/" "baz2/bar222" 2756 S: * LIST (\Subscribed) "/" "eps2" 2757 S: * LIST (\Subscribed) "/" "eps2/mamba" 2758 S: * LIST (\Subscribed) "/" "qux2/bar2" 2759 S: D02 OK done 2760 The client issues the following command first: 2762 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 2763 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2764 S: * LIST (\Subscribed) "/" "foo2/bar2" 2765 S: * LIST (\Subscribed) "/" "baz2/bar2" 2766 S: * LIST (\Subscribed) "/" "baz2/bar22" 2767 S: * LIST (\Subscribed) "/" "baz2/bar222" 2768 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2769 S: * LIST (\Subscribed) "/" "qux2/bar2" 2770 S: D03 OK done 2772 and the server may also include (but this would violate a SHOULD 2773 NOT in Section 3.5, because CHILDINFO is redundant) 2775 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2776 S: * LIST (\NonExistent) "/" "qux2" ("CHILDINFO" ("SUBSCRIBED")) 2778 The CHILDINFO extended data item is returned for mailboxes 2779 "foo2", "baz2", and "eps2", because all of them have subscribed 2780 children, even though for the mailbox "foo2" only one of the two 2781 subscribed children matches the pattern, for the mailbox "baz2" 2782 all the subscribed children match the pattern, and for the 2783 mailbox "eps2" none of the subscribed children matches the 2784 pattern. 2786 Note that if the client issues 2788 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 2789 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2790 S: * LIST (\Subscribed) "/" "foo2/bar1" 2791 S: * LIST (\Subscribed) "/" "foo2/bar2" 2792 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2793 S: * LIST (\Subscribed) "/" "baz2/bar2" 2794 S: * LIST (\Subscribed) "/" "baz2/bar22" 2795 S: * LIST (\Subscribed) "/" "baz2/bar222" 2796 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2797 S: * LIST (\Subscribed) "/" "eps2/mamba" 2798 S: * LIST (\Subscribed) "/" "qux2/bar2" 2799 S: D03 OK done 2801 The LIST responses for mailboxes "foo2", "baz2", and "eps2" 2802 still have the CHILDINFO extended data item, even though this 2803 information is redundant and the client can determine it by 2804 itself. 2806 9: The following example shows usage of extended syntax for mailbox 2807 pattern. It also demonstrates that the presence of the 2808 CHILDINFO extended data item doesn't necessarily imply 2809 \HasChildren. 2811 C: a1 LIST "" ("foo") 2812 S: * LIST () "/" foo 2813 S: a1 OK done 2815 C: a2 LIST (SUBSCRIBED) "" "foo/*" 2816 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 2817 S: a2 OK done 2819 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN (CHILDREN) 2820 S: * LIST (\HasNoChildren) "/" foo ("CHILDINFO" ("SUBSCRIBED")) 2821 S: a3 OK done 2823 10: The following example shows how a server that supports missing 2824 mailbox hierarchy elements can signal to a client that didn't 2825 specify the RECURSIVEMATCH selection option that there is a 2826 child mailbox that matches the selection criteria. 2828 C: a1 LIST (REMOTE) "" * 2829 S: * LIST () "/" music/rock 2830 S: * LIST (\Remote) "/" also/jazz 2831 S: a1 OK done 2833 C: a2 LIST () "" % 2834 S: * LIST (\NonExistent \HasChildren) "/" music 2835 S: a2 OK done 2837 C: a3 LIST (REMOTE) "" % 2838 S: * LIST (\NonExistent \HasChildren) "/" music 2839 S: * LIST (\NonExistent \HasChildren) "/" also 2840 S: a3 OK done 2842 C: a3.1 LIST "" (% music/rock) 2843 S: * LIST () "/" music/rock 2844 S: a3.1 OK done 2846 Because "music/rock" is the only mailbox under "music", there's 2847 no need for the server to also return "music". However clients 2848 must handle both cases. 2850 11: The following examples show use of STATUS return option. 2852 C: A01 LIST "" % RETURN (STATUS (MESSAGES UNSEEN)) 2853 S: * LIST () "." "INBOX" 2854 S: * STATUS "INBOX" (MESSAGES 17 UNSEEN 16) 2855 S: * LIST () "." "foo" 2856 S: * STATUS "foo" (MESSAGES 30 UNSEEN 29) 2857 S: * LIST (\NoSelect) "." "bar" 2858 S: A01 OK List completed. 2860 The "bar" mailbox isn't selectable, so it has no STATUS reply. 2862 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (STATUS 2863 (MESSAGES)) 2864 S: * LIST (\Subscribed) "." "INBOX" 2865 S: * STATUS "INBOX" (MESSAGES 17) 2866 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED")) 2867 S: A02 OK List completed. 2869 The LIST reply for "foo" is returned because it has matching 2870 children, but no STATUS reply is returned because "foo" itself 2871 doesn't match the selection criteria. 2873 6.3.10. NAMESPACE Command 2875 Arguments: none 2877 Responses: REQUIRED untagged responses: NAMESPACE 2879 Result: OK - command completed 2880 NO - Can't complete the command 2881 BAD - arguments invalid 2883 The NAMESPACE command causes a single ungagged NAMESPACE response to 2884 be returned. The untagged NAMESPACE response contains the prefix and 2885 hierarchy delimiter to the server's Personal Namespace(s), Other 2886 Users' Namespace(s), and Shared Namespace(s) that the server wishes 2887 to expose. The response will contain a NIL for any namespace class 2888 that is not available. The Namespace-Response-Extensions ABNF non 2889 terminal is defined for extensibility and MAY be included in the 2890 NAMESPACE response. 2892 Example 1: 2894 In this example a server supports a single personal namespace. No 2895 leading prefix is used on personal mailboxes and "/" is the hierarchy 2896 delimiter. 2898 C: A001 NAMESPACE 2899 S: * NAMESPACE (("" "/")) NIL NIL 2900 S: A001 OK NAMESPACE command completed 2902 Example 2: 2904 A user logged on anonymously to a server. No personal mailboxes are 2905 associated with the anonymous user and the user does not have access 2906 to the Other Users' Namespace. No prefix is required to access 2907 shared mailboxes and the hierarchy delimiter is "." 2909 C: A001 NAMESPACE 2910 S: * NAMESPACE NIL NIL (("" ".")) 2911 S: A001 OK NAMESPACE command completed 2913 Example 3: 2915 A server that contains a Personal Namespace and a single Shared 2916 Namespace. 2918 C: A001 NAMESPACE 2919 S: * NAMESPACE (("" "/")) NIL (("Public Folders/" "/")) 2920 S: A001 OK NAMESPACE command completed 2922 Example 4: 2924 A server that contains a Personal Namespace, Other Users' Namespace 2925 and multiple Shared Namespaces. Note that the hierarchy delimiter 2926 used within each namespace can be different. 2928 C: A001 NAMESPACE 2929 S: * NAMESPACE (("" "/")) (("~" "/")) (("#shared/" "/") 2930 ("#public/" "/")("#ftp/" "/")("#news." ".")) 2931 S: A001 OK NAMESPACE command completed 2933 The prefix string allows a client to do things such as automatically 2934 creating personal mailboxes or LISTing all available mailboxes within 2935 a namespace. 2937 Example 5: 2939 A server that supports only the Personal Namespace, with a leading 2940 prefix of INBOX to personal mailboxes and a hierarchy delimiter of 2941 "." 2942 C: A001 NAMESPACE 2943 S: * NAMESPACE (("INBOX." ".")) NIL NIL 2944 S: A001 OK NAMESPACE command completed 2946 < Automatically create a mailbox to store sent items.> 2948 C: A002 CREATE "INBOX.Sent Mail" 2949 S: A002 OK CREATE command completed 2951 Although typically a server will support only a single Personal 2952 Namespace, and a single Other User's Namespace, circumstances exist 2953 where there MAY be multiples of these, and a client MUST be prepared 2954 for them. If a client is configured such that it is required to 2955 create a certain mailbox, there can be circumstances where it is 2956 unclear which Personal Namespaces it should create the mailbox in. 2957 In these situations a client SHOULD let the user select which 2958 namespaces to create the mailbox in or just use the first personal 2959 namespace. 2961 Example 6: 2963 In this example, a server supports 2 Personal Namespaces. In 2964 addition to the regular Personal Namespace, the user has an 2965 additional personal namespace to allow access to mailboxes in an MH 2966 format mailstore. 2968 The client is configured to save a copy of all mail sent by the user 2969 into a mailbox called 'Sent Mail'. Furthermore, after a message is 2970 deleted from a mailbox, the client is configured to move that message 2971 to a mailbox called 'Deleted Items'. 2973 Note that this example demonstrates how some extension flags can be 2974 passed to further describe the #mh namespace. 2976 C: A001 NAMESPACE 2977 S: * NAMESPACE (("" "/")("#mh/" "/" "X-PARAM" 2978 ("FLAG1" "FLAG2"))) NIL NIL 2979 S: A001 OK NAMESPACE command completed 2981 < It is desired to keep only one copy of sent mail. 2982 It is unclear which Personal Namespace the client 2983 should use to create the 'Sent Mail' mailbox. 2984 The user is prompted to select a namespace and only 2985 one 'Sent Mail' mailbox is created. > 2987 C: A002 CREATE "Sent Mail" 2988 S: A002 OK CREATE command completed 2990 < The client is designed so that it keeps two 2991 'Deleted Items' mailboxes, one for each namespace. > 2993 C: A003 CREATE "Delete Items" 2994 S: A003 OK CREATE command completed 2996 C: A004 CREATE "#mh/Deleted Items" 2997 S: A004 OK CREATE command completed 2999 The next level of hierarchy following the Other Users' Namespace 3000 prefix SHOULD consist of , where is a user name 3001 as per the LOGIN or AUTHENTICATE command. 3003 A client can construct a LIST command by appending a "%" to the Other 3004 Users' Namespace prefix to discover the Personal Namespaces of other 3005 users that are available to the currently authenticated user. 3007 In response to such a LIST command, a server SHOULD NOT return user 3008 names that have not granted access to their personal mailboxes to the 3009 user in question. 3011 A server MAY return a LIST response containing only the names of 3012 users that have explicitly granted access to the user in question. 3014 Alternatively, a server MAY return NO to such a LIST command, 3015 requiring that a user name be included with the Other Users' 3016 Namespace prefix before listing any other user's mailboxes. 3018 Example 7: 3020 A server that supports providing a list of other user's mailboxes 3021 that are accessible to the currently logged on user. 3023 C: A001 NAMESPACE 3024 S: * NAMESPACE (("" "/")) (("Other Users/" "/")) NIL 3025 S: A001 OK NAMESPACE command completed 3027 C: A002 LIST "" "Other Users/%" 3028 S: * LIST () "/" "Other Users/Mike" 3029 S: * LIST () "/" "Other Users/Karen" 3030 S: * LIST () "/" "Other Users/Matthew" 3031 S: * LIST () "/" "Other Users/Tesa" 3032 S: A002 OK LIST command completed 3034 Example 8: 3036 A server that does not support providing a list of other user's 3037 mailboxes that are accessible to the currently logged on user. The 3038 mailboxes are listable if the client includes the name of the other 3039 user with the Other Users' Namespace prefix. 3041 C: A001 NAMESPACE 3042 S: * NAMESPACE (("" "/")) (("#Users/" "/")) NIL 3043 S: A001 OK NAMESPACE command completed 3045 < In this example, the currently logged on user has access to 3046 the Personal Namespace of user Mike, but the server chose to 3047 suppress this information in the LIST response. However, 3048 by appending the user name Mike (received through user input) 3049 to the Other Users' Namespace prefix, the client is able 3050 to get a listing of the personal mailboxes of user Mike. > 3052 C: A002 LIST "" "#Users/%" 3053 S: A002 NO The requested item could not be found. 3055 C: A003 LIST "" "#Users/Mike/%" 3056 S: * LIST () "/" "#Users/Mike/INBOX" 3057 S: * LIST () "/" "#Users/Mike/Foo" 3058 S: A003 OK LIST command completed. 3060 A prefix string might not contain a hierarchy delimiter, because in 3061 some cases it is not needed as part of the prefix. 3063 Example 9: 3065 A server that allows access to the Other Users' Namespace by 3066 prefixing the others' mailboxes with a '~' followed by , 3067 where is a user name as per the LOGIN or AUTHENTICATE 3068 command. 3070 C: A001 NAMESPACE 3071 S: * NAMESPACE (("" "/")) (("~" "/")) NIL 3072 S: A001 OK NAMESPACE command completed 3074 < List the mailboxes for user mark > 3076 C: A002 LIST "" "~mark/%" 3077 S: * LIST () "/" "~mark/INBOX" 3078 S: * LIST () "/" "~mark/foo" 3079 S: A002 OK LIST command completed 3081 6.3.11. STATUS Command 3083 Arguments: mailbox name 3084 status data item names 3086 Responses: REQUIRED untagged responses: STATUS 3088 Result: OK - status completed 3089 NO - status failure: no status for that name 3090 BAD - command unknown or arguments invalid 3092 The STATUS command requests the status of the indicated mailbox. It 3093 does not change the currently selected mailbox, nor does it affect 3094 the state of any messages in the queried mailbox. 3096 The STATUS command provides an alternative to opening a second 3097 IMAP4rev2 connection and doing an EXAMINE command on a mailbox to 3098 query that mailbox's status without deselecting the current mailbox 3099 in the first IMAP4rev2 connection. 3101 Unlike the LIST command, the STATUS command is not guaranteed to be 3102 fast in its response. Under certain circumstances, it can be quite 3103 slow. In some implementations, the server is obliged to open the 3104 mailbox read-only internally to obtain certain status information. 3105 Also unlike the LIST command, the STATUS command does not accept 3106 wildcards. 3108 Note: The STATUS command is intended to access the status of 3109 mailboxes other than the currently selected mailbox. Because the 3110 STATUS command can cause the mailbox to be opened internally, and 3111 because this information is available by other means on the 3112 selected mailbox, the STATUS command SHOULD NOT be used on the 3113 currently selected mailbox. However, servers MUST be able to 3114 execute STATUS command on the selected mailbox. (This might also 3115 implicitly happen when STATUS return option is used in a LIST 3116 command). 3118 The STATUS command MUST NOT be used as a "check for new messages 3119 in the selected mailbox" operation (refer to sections Section 7, 3120 Section 7.3.1 for more information about the proper method for new 3121 message checking). 3123 STATUS SIZE (see below) can take a significant amount of time, 3124 depending upon server implementation. Clients should use STATUS 3125 SIZE cautiously. 3127 The currently defined status data items that can be requested are: 3129 MESSAGES The number of messages in the mailbox. 3131 UIDNEXT The next unique identifier value of the mailbox. Refer to 3132 Section 2.3.1.1 for more information. 3134 UIDVALIDITY The unique identifier validity value of the mailbox. 3135 Refer to Section 2.3.1.1 for more information. 3137 UNSEEN The number of messages which do not have the \Seen flag set. 3139 DELETED The number of messages which have the \Deleted flag set. 3141 SIZE The total size of the mailbox in octets. This is not strictly 3142 required to be an exact value, but it MUST be equal to or greater 3143 than the sum of the values of the RFC822.SIZE FETCH message data 3144 items (see Section 6.4.5) of all messages in the mailbox. 3146 Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES) 3147 S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 3148 S: A042 OK STATUS completed 3150 6.3.12. APPEND Command 3152 Arguments: mailbox name 3153 OPTIONAL flag parenthesized list 3154 OPTIONAL date/time string 3155 message literal 3157 Responses: OPTIONAL untagged response: LIST 3159 Result: OK - append completed 3160 NO - append error: can't append to that mailbox, error 3161 in flags or date/time or message text 3162 BAD - command unknown or arguments invalid 3164 The APPEND command appends the literal argument as a new message to 3165 the end of the specified destination mailbox. This argument SHOULD 3166 be in the format of an [RFC-5322] or [I18N-HDRS] message. 8-bit 3167 characters are permitted in the message. A server implementation 3168 that is unable to preserve 8-bit data properly MUST be able to 3169 reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB] 3170 content transfer encoding. 3172 Note: There may be exceptions, e.g., draft messages, in which 3173 required [RFC-5322] header lines are omitted in the message 3174 literal argument to APPEND. The full implications of doing so 3175 must be understood and carefully weighed. 3177 If a flag parenthesized list is specified, the flags SHOULD be set in 3178 the resulting message; otherwise, the flag list of the resulting 3179 message is set to empty by default. 3181 If a date-time is specified, the internal date SHOULD be set in the 3182 resulting message; otherwise, the internal date of the resulting 3183 message is set to the current date and time by default. 3185 If the append is unsuccessful for any reason, the mailbox MUST be 3186 restored to its state before the APPEND attempt (other than possibly 3187 keeping the changed mailbox's UIDNEXT value); no partial appending is 3188 permitted. 3190 If the destination mailbox does not exist, a server MUST return an 3191 error, and MUST NOT automatically create the mailbox. Unless it is 3192 certain that the destination mailbox can not be created, the server 3193 MUST send the response code "[TRYCREATE]" as the prefix of the text 3194 of the tagged NO response. This gives a hint to the client that it 3195 can attempt a CREATE command and retry the APPEND if the CREATE is 3196 successful. 3198 On successful completion of an APPEND, the server SHOULD return an 3199 APPENDUID response code (see Section 7.1). 3201 In the case of a mailbox that has permissions set so that the client 3202 can APPEND to the mailbox, but not SELECT or EXAMINE it, the server 3203 SHOULD NOT send an APPENDUID response code as it would disclose 3204 information about the mailbox. 3206 In the case of a mailbox that has UIDNOTSTICKY status (see 3207 Section 7.1), the server MAY omit the APPENDUID response code as it 3208 is not meaningful. 3210 If the server does not return the APPENDUID response codes, the 3211 client can discover this information by selecting the destination 3212 mailbox. The location of messages placed in the destination mailbox 3213 by APPEND can be determined by using FETCH and/or SEARCH commands 3214 (e.g., for Message-ID or some unique marker placed in the message in 3215 an APPEND). 3217 If the mailbox is currently selected, the normal new message actions 3218 SHOULD occur. Specifically, the server SHOULD notify the client 3219 immediately via an untagged EXISTS response. If the server does not 3220 do so, the client MAY issue a NOOP command after one or more APPEND 3221 commands. 3223 If the server decides to convert (normalize) the mailbox name, it 3224 SHOULD return an untagged LIST with OLDNAME extended data item, with 3225 the OLDNAME value being the supplied mailbox name and the name 3226 parameter being the normalized mailbox name. (See Section 6.3.9.7 3227 for more details.) 3229 Example: C: A003 APPEND saved-messages (\Seen) {310} 3230 S: + Ready for literal data 3231 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3232 C: From: Fred Foobar 3233 C: Subject: afternoon meeting 3234 C: To: mooch@owatagu.siam.edu 3235 C: Message-Id: 3236 C: MIME-Version: 1.0 3237 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3238 C: 3239 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3240 C: 3241 S: A003 OK APPEND completed 3243 Example: C: A003 APPEND saved-messages (\Seen) {297} 3244 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3245 C: From: Fred Foobar 3246 C: Subject: afternoon meeting 3247 C: To: mooch@example.com 3248 C: Message-Id: 3249 C: MIME-Version: 1.0 3250 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3251 C: 3252 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3253 C: 3254 S: A003 OK [APPENDUID 38505 3955] APPEND completed 3255 C: A004 COPY 2:4 meeting 3256 S: A004 OK [COPYUID 38505 304,319:320 3956:3958] Done 3257 C: A005 UID COPY 305:310 meeting 3258 S: A005 OK No matching messages, so nothing copied 3259 C: A006 COPY 2 funny 3260 S: A006 OK Done 3261 C: A007 SELECT funny 3262 S: * 1 EXISTS 3263 S: * OK [UIDVALIDITY 3857529045] Validity session-only 3264 S: * OK [UIDNEXT 2] Predicted next UID 3265 S: * NO [UIDNOTSTICKY] Non-persistent UIDs 3266 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 3267 S: * OK [PERMANENTFLAGS (\Deleted \Seen)] Limited 3268 S: * LIST () "." funny 3269 S: A007 OK [READ-WRITE] SELECT completed 3271 In this example, A003 and A004 demonstrate successful appending and 3272 copying to a mailbox that returns the UIDs assigned to the messages. 3273 A005 is an example in which no messages were copied; this is because 3274 in A003, we see that message 2 had UID 304, and message 3 had UID 3275 319; therefore, UIDs 305 through 310 do not exist (refer to 3276 Section 2.3.1.1 for further explanation). A006 is an example of a 3277 message being copied that did not return a COPYUID; and, as expected, 3278 A007 shows that the mail store containing that mailbox does not 3279 support persistent UIDs. 3281 Note: The APPEND command is not used for message delivery, because 3282 it does not provide a mechanism to transfer [SMTP] envelope 3283 information. 3285 6.3.13. IDLE Command 3287 Arguments: none 3289 Responses: continuation data will be requested; the client sends the 3290 continuation data "DONE" to end the command 3292 Result: OK - IDLE completed after client sent "DONE" 3293 NO - failure: the server will not allow the IDLE command 3294 at this time 3295 BAD - command unknown or arguments invalid 3297 Without the IDLE command a client requires to poll the server for 3298 changes to the selected mailbox (new mail, deletions, flag changes). 3299 It's often more desirable to have the server transmit updates to the 3300 client in real time. This allows a user to see new mail immediately. 3301 The IDLE command allows a client to tell the server that it's ready 3302 to accept such real-time updates. 3304 The IDLE command is sent from the client to the server when the 3305 client is ready to accept unsolicited update messages. The server 3306 requests a response to the IDLE command using the continuation ("+") 3307 response. The IDLE command remains active until the client responds 3308 to the continuation, and as long as an IDLE command is active, the 3309 server is now free to send untagged EXISTS, EXPUNGE, FETCH, and other 3310 responses at any time. If the server choose to send unsolicited 3311 FETCH responses, they MUST include UID FETCH item. 3313 The IDLE command is terminated by the receipt of a "DONE" 3314 continuation from the client; such response satisfies the server's 3315 continuation request. At that point, the server MAY send any 3316 remaining queued untagged responses and then MUST immediately send 3317 the tagged response to the IDLE command and prepare to process other 3318 commands. As for other commands, the processing of any new command 3319 may cause the sending of unsolicited untagged responses, subject to 3320 the ambiguity limitations. The client MUST NOT send a command while 3321 the server is waiting for the DONE, since the server will not be able 3322 to distinguish a command from a continuation. 3324 The server MAY consider a client inactive if it has an IDLE command 3325 running, and if such a server has an inactivity timeout it MAY log 3326 the client off implicitly at the end of its timeout period. Because 3327 of that, clients using IDLE are advised to terminate the IDLE and re- 3328 issue it at least every 29 minutes to avoid being logged off. This 3329 still allows a client to receive immediate mailbox updates even 3330 though it need only "poll" at half hour intervals. 3332 Example: C: A001 SELECT INBOX 3333 S: * FLAGS (\Deleted \Seen \Flagged) 3334 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Flagged)] Limited 3335 S: * 3 EXISTS 3336 S: * OK [UIDVALIDITY 1] 3337 S: * LIST () "/" INBOX 3338 S: A001 OK [READ-WRITE] SELECT completed 3339 C: A002 IDLE 3340 S: + idling 3341 ...time passes; new mail arrives... 3342 S: * 4 EXISTS 3343 C: DONE 3344 S: A002 OK IDLE terminated 3345 ...another client expunges message 2 now... 3346 C: A003 FETCH 4 ALL 3347 S: * 4 FETCH (...) 3348 S: A003 OK FETCH completed 3349 C: A004 IDLE 3350 S: * 2 EXPUNGE 3351 S: * 3 EXISTS 3352 S: + idling 3353 ...time passes; another client expunges message 3... 3354 S: * 3 EXPUNGE 3355 S: * 2 EXISTS 3356 ...time passes; new mail arrives... 3357 S: * 3 EXISTS 3358 C: DONE 3359 S: A004 OK IDLE terminated 3360 C: A005 FETCH 3 ALL 3361 S: * 3 FETCH (...) 3362 S: A005 OK FETCH completed 3363 C: A006 IDLE 3365 6.4. Client Commands - Selected State 3367 In the selected state, commands that manipulate messages in a mailbox 3368 are permitted. 3370 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 3371 and the authenticated state commands (SELECT, EXAMINE, NAMESPACE, 3372 CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, STATUS, and 3373 APPEND), the following commands are valid in the selected state: 3374 CLOSE, UNSELECT, EXPUNGE, SEARCH, FETCH, STORE, COPY, MOVE, and UID. 3376 6.4.1. CLOSE Command 3378 Arguments: none 3380 Responses: no specific responses for this command 3382 Result: OK - close completed, now in authenticated state 3383 BAD - command unknown or arguments invalid 3385 The CLOSE command permanently removes all messages that have the 3386 \Deleted flag set from the currently selected mailbox, and returns to 3387 the authenticated state from the selected state. No untagged EXPUNGE 3388 responses are sent. 3390 No messages are removed, and no error is given, if the mailbox is 3391 selected by an EXAMINE command or is otherwise selected read-only. 3393 Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT command 3394 MAY be issued without previously issuing a CLOSE command. The 3395 SELECT, EXAMINE, and LOGOUT commands implicitly close the currently 3396 selected mailbox without doing an expunge. However, when many 3397 messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT sequence is 3398 considerably faster than an EXPUNGE-LOGOUT or EXPUNGE-SELECT because 3399 no untagged EXPUNGE responses (which the client would probably 3400 ignore) are sent. 3402 Example: C: A341 CLOSE 3403 S: A341 OK CLOSE completed 3405 6.4.2. UNSELECT Command 3407 Arguments: none 3409 Responses: no specific responses for this command 3411 Result: OK - unselect completed, now in authenticated state 3412 BAD - no mailbox selected, or argument supplied but none 3413 permitted 3415 The UNSELECT command frees server's resources associated with the 3416 selected mailbox and returns the server to the authenticated state. 3417 This command performs the same actions as CLOSE, except that no 3418 messages are permanently removed from the currently selected mailbox. 3420 Example: C: A342 UNSELECT 3421 S: A342 OK Unselect completed 3423 6.4.3. EXPUNGE Command 3425 Arguments: none 3427 Responses: untagged responses: EXPUNGE 3429 Result: OK - expunge completed 3430 NO - expunge failure: can't expunge (e.g., permission 3431 denied) 3432 BAD - command unknown or arguments invalid 3434 The EXPUNGE command permanently removes all messages that have the 3435 \Deleted flag set from the currently selected mailbox. Before 3436 returning an OK to the client, an untagged EXPUNGE response is sent 3437 for each message that is removed. 3439 Example: C: A202 EXPUNGE 3440 S: * 3 EXPUNGE 3441 S: * 3 EXPUNGE 3442 S: * 5 EXPUNGE 3443 S: * 8 EXPUNGE 3444 S: A202 OK EXPUNGE completed 3446 Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag 3447 set. See the description of the EXPUNGE response for further 3448 explanation. 3450 6.4.4. SEARCH Command 3452 Arguments: OPTIONAL result specifier 3453 OPTIONAL [CHARSET] specification 3454 searching criteria (one or more) 3456 Responses: OPTIONAL untagged response: ESEARCH 3458 Result: OK - search completed 3459 NO - search error: can't search that [CHARSET] or 3460 criteria 3461 BAD - command unknown or arguments invalid 3463 The SEARCH command searches the mailbox for messages that match the 3464 given searching criteria. 3466 The SEARCH command may contain result options. Result options 3467 control what kind of information is returned about messages matching 3468 the search criteria in an untagged ESEARCH response. If no result 3469 option is specified or empty list of options is specified "()", ALL 3470 is assumed (see below). The order of individual options is 3471 arbitrary. Individual options may contain parameters enclosed in 3472 parentheses (*). If an option has parameters, they consist of atoms 3473 and/or strings and/or lists in a specific order. Any options not 3474 defined by extensions that the server supports must be rejected with 3475 a BAD response. 3477 (*) - if an option has a mandatory parameter, which can always be 3478 represented as a number or a sequence-set, the option parameter does 3479 not need the enclosing (). See the ABNF for more details. 3481 This document specifies the following result options: 3483 MIN 3485 Return the lowest message number/UID that satisfies the SEARCH 3486 criteria. 3488 If the SEARCH results in no matches, the server MUST NOT 3489 include the MIN result option in the ESEARCH response; however, 3490 it still MUST send the ESEARCH response. 3492 MAX 3494 Return the highest message number/UID that satisfies the SEARCH 3495 criteria. 3497 If the SEARCH results in no matches, the server MUST NOT 3498 include the MAX result option in the ESEARCH response; however, 3499 it still MUST send the ESEARCH response. 3501 ALL 3503 Return all message numbers/UIDs that satisfy the SEARCH 3504 criteria using the sequence-set syntax. Note, the client MUST 3505 NOT assume that messages/UIDs will be listed in any particular 3506 order. 3508 If the SEARCH results in no matches, the server MUST NOT 3509 include the ALL result option in the ESEARCH response; however, 3510 it still MUST send the ESEARCH response. 3512 COUNT Return number of the messages that satisfy the SEARCH 3513 criteria. This result option MUST always be included in the 3514 ESEARCH response. 3516 SAVE 3517 This option tells the server to remember the result of the 3518 SEARCH or UID SEARCH command (as well as any command based on 3519 SEARCH, e.g., SORT and THREAD [RFC5256]>) and store it in an 3520 internal variable that we will reference as the "search result 3521 variable". The client can use the "$" marker to reference the 3522 content of this internal variable. The "$" marker can be used 3523 instead of message sequence or UID sequence in order to 3524 indicate that the server should substitute it with the list of 3525 messages from the search result variable. Thus, the client can 3526 use the result of the latest remembered SEARCH command as a 3527 parameter to another command. See Section 6.4.4.1 for details 3528 on how the value of the search result variable is determined, 3529 how it is affected by other commands executed, and how SAVE 3530 return option interacts with other return options. 3532 In absence of any other SEARCH result option, the SAVE result 3533 option also suppresses any ESEARCH response that would have 3534 been otherwise returned by the SEARCH command. 3536 Note: future extensions to this document can allow servers to return 3537 multiple ESEARCH responses for a single extended SEARCH command. 3538 However all options specified above MUST result in a single ESEARCH 3539 response if used by themselves or in a combination. This guaranty 3540 simplifies processing in IMAP4rev2 clients. Future SEARCH extensions 3541 that relax this restriction will have to describe how results from 3542 multiple ESEARCH responses are to be amalgamated. 3544 Searching criteria consist of one or more search keys. 3546 When multiple keys are specified, the result is the intersection (AND 3547 function) of all the messages that match those keys. For example, 3548 the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers to all 3549 deleted messages from Smith with INTERNALDATE greater than February 3550 1, 1994. A search key can also be a parenthesized list of one or 3551 more search keys (e.g., for use with the OR and NOT keys). 3553 Server implementations MAY exclude [MIME-IMB] body parts with 3554 terminal content media types other than TEXT and MESSAGE from 3555 consideration in SEARCH matching. 3557 The OPTIONAL [CHARSET] specification consists of the word "CHARSET" 3558 followed by a registered [CHARSET] [CHARSET-REG]. It indicates the 3559 [CHARSET] of the strings that appear in the search criteria. 3560 [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in 3561 [RFC-5322]/[MIME-IMB] headers, MUST be decoded before comparing text. 3562 Servers MUST support US-ASCII and UTF-8 charsets; other [CHARSET]s 3563 MAY be supported. Clients SHOULD use UTF-8. Note that if "CHARSET" 3564 is not provided IMAP4rev2 server MUST assume UTF-8, so selecting 3565 CHARSET UTF-8 is redundant. It is permitted for improved 3566 compatibility with existing IMAP4rev1 clients. 3568 If the server does not support the specified [CHARSET], it MUST 3569 return a tagged NO response (not a BAD). This response SHOULD 3570 contain the BADCHARSET response code, which MAY list the [CHARSET]s 3571 supported by the server. 3573 In all search keys that use strings and unless specified otherwise, a 3574 message matches the key if the string is a substring of the 3575 associated text. The matching SHOULD be case-insensitive for 3576 characters within ASCII range. Consider using [IMAP-I18N] for 3577 language-sensitive case-insensitive searching. Note that the empty 3578 string is a substring; this is useful when doing a HEADER search in 3579 order to test for a header field presence in the message. 3581 The defined search keys are as follows. Refer to the Formal Syntax 3582 section for the precise syntactic definitions of the arguments. 3584 Messages with message sequence numbers corresponding 3585 to the specified message sequence number set. 3587 ALL All messages in the mailbox; the default initial key for ANDing. 3589 ANSWERED Messages with the \Answered flag set. 3591 BCC Messages that contain the specified string in the 3592 envelope structure's BCC field. 3594 BEFORE Messages whose internal date (disregarding time and 3595 timezone) is earlier than the specified date. 3597 BODY Messages that contain the specified string in the body 3598 of the message. Unlike TEXT (see below), this doesn't match any 3599 header fields. Servers are allowed to implement flexible matching 3600 for this search key, for example matching "swim" to both "swam" 3601 and "swum" in English language text or only doing full word 3602 matching (where "swim" will not match "swimming"). 3604 CC Messages that contain the specified string in the 3605 envelope structure's CC field. 3607 DELETED Messages with the \Deleted flag set. 3609 DRAFT Messages with the \Draft flag set. 3611 FLAGGED Messages with the \Flagged flag set. 3613 FROM Messages that contain the specified string in the 3614 envelope structure's FROM field. 3616 HEADER Messages that have a header with the 3617 specified field-name (as defined in [RFC-5322]) and that contains 3618 the specified string in the text of the header (what comes after 3619 the colon). If the string to search is zero-length, this matches 3620 all messages that have a header line with the specified field-name 3621 regardless of the contents. Servers should use substring search 3622 for this SEARCH item, as clients can use it for automatic 3623 processing not initiated by end users. For example this can be 3624 used for searching for Message-ID or Content-Type header field 3625 values that need to be exact, or for searches in header fields 3626 that the IMAP server might not know anything about. 3628 KEYWORD Messages with the specified keyword flag set. 3630 LARGER Messages with an [RFC-5322] size larger than the 3631 specified number of octets. 3633 NOT Messages that do not match the specified search 3634 key. 3636 ON Messages whose internal date (disregarding time and 3637 timezone) is within the specified date. 3639 OR Messages that match either search 3640 key. 3642 SEEN Messages that have the \Seen flag set. 3644 SENTBEFORE Messages whose [RFC-5322] Date: header 3645 (disregarding time and timezone) is earlier than the specified 3646 date. 3648 SENTON Messages whose [RFC-5322] Date: header (disregarding 3649 time and timezone) is within the specified date. 3651 SENTSINCE Messages whose [RFC-5322] Date: header 3652 (disregarding time and timezone) is within or later than the 3653 specified date. 3655 SINCE Messages whose internal date (disregarding time and 3656 timezone) is within or later than the specified date. 3658 SMALLER Messages with an [RFC-5322] size smaller than the 3659 specified number of octets. 3661 SUBJECT Messages that contain the specified string in the 3662 envelope structure's SUBJECT field. 3664 TEXT Messages that contain the specified string in the 3665 header (including MIME header fields) or body of the message. 3666 Servers are allowed to implement flexible matching for this search 3667 key, for example matching "swim" to both "swam" and "swum" in 3668 English language text or only doing full word matching (where 3669 "swim" will not match "swimming"). 3671 TO Messages that contain the specified string in the 3672 envelope structure's TO field. 3674 UID Messages with unique identifiers corresponding to 3675 the specified unique identifier set. Sequence set ranges are 3676 permitted. 3678 UNANSWERED Messages that do not have the \Answered flag set. 3680 UNDELETED Messages that do not have the \Deleted flag set. 3682 UNDRAFT Messages that do not have the \Draft flag set. 3684 UNFLAGGED Messages that do not have the \Flagged flag set. 3686 UNKEYWORD Messages that do not have the specified keyword 3687 flag set. 3689 UNSEEN Messages that do not have the \Seen flag set. 3691 Example: C: A282 SEARCH RETURN (MIN COUNT) FLAGGED 3692 SINCE 1-Feb-1994 NOT FROM "Smith" 3693 S: * ESEARCH (TAG "A282") MIN 2 COUNT 3 3694 S: A282 OK SEARCH completed 3696 Example: C: A283 SEARCH RETURN () FLAGGED 3697 SINCE 1-Feb-1994 NOT FROM "Smith" 3698 S: * ESEARCH (TAG "A283") ALL 2,10:11 3699 S: A283 OK SEARCH completed 3701 Example: C: A284 SEARCH TEXT "string not in mailbox" 3702 S: * ESEARCH (TAG "A284") 3703 S: A284 OK SEARCH completed 3704 C: A285 SEARCH CHARSET UTF-8 TEXT {6} 3705 S: + Ready for literal text 3706 C: XXXXXX 3707 S: * ESEARCH (TAG "A285") ALL 43 3708 S: A285 OK SEARCH completed 3710 Note: Since this document is restricted to 7-bit ASCII text, it is 3711 not possible to show actual UTF-8 data. The "XXXXXX" is a 3712 placeholder for what would be 6 octets of 8-bit data in an actual 3713 transaction. 3715 The following example demonstrates finding the first unseen message 3716 in the mailbox: 3718 Example: C: A284 SEARCH RETURN (MIN) UNSEEN 3719 S: * ESEARCH (TAG "A284") MIN 4 3720 S: A284 OK SEARCH completed 3722 The following example demonstrates that if the ESEARCH UID indicator 3723 is present, all data in the ESEARCH response is referring to UIDs; 3724 for example, the MIN result specifier will be followed by a UID. 3726 Example: C: A285 UID SEARCH RETURN (MIN MAX) 1:5000 3727 S: * ESEARCH (TAG "A285") UID MIN 7 MAX 3800 3728 S: A285 OK SEARCH completed 3730 The following example demonstrates returning the number of deleted 3731 messages: 3733 Example: C: A286 SEARCH RETURN (COUNT) DELETED 3734 S: * ESEARCH (TAG "A286") COUNT 15 3735 S: A286 OK SEARCH completed 3737 6.4.4.1. SAVE result option and SEARCH result variable 3739 Upon successful completion of a SELECT or an EXAMINE command (after 3740 the tagged OK response), the current search result variable is reset 3741 to the empty sequence. 3743 A successful SEARCH command with the SAVE result option sets the 3744 value of the search result variable to the list of messages found in 3745 the SEARCH command. For example, if no messages were found, the 3746 search result variable will contain the empty sequence. 3748 Any of the following SEARCH commands MUST NOT change the search 3749 result variable: 3751 a SEARCH command that caused the server to return the BAD tagged 3752 response, 3754 a SEARCH command with no SAVE result option that caused the server 3755 to return NO tagged response, 3757 a successful SEARCH command with no SAVE result option. 3759 A SEARCH command with the SAVE result option that caused the server 3760 to return the NO tagged response sets the value of the search result 3761 variable to the empty sequence. 3763 When a message listed in the search result variable is EXPUNGEd, it 3764 is automatically removed from the list. Implementors are reminded 3765 that if the server stores the list as a list of message numbers, it 3766 MUST automatically adjust them when notifying the client about 3767 expunged messages, as described in Section 7.4.1. 3769 If the server decides to send a new UIDVALIDITY value while the 3770 mailbox is opened, this causes resetting of the search variable to 3771 the empty sequence. 3773 Note that even if the "$" marker contains the empty sequence of 3774 messages, it must be treated by all commands accepting message sets 3775 as parameters as a valid, but non-matching list of messages. For 3776 example, the "FETCH $" command would return a tagged OK response and 3777 no FETCH responses. See also the Example 5 in Section 6.4.4.4. 3779 The SAVE result option doesn't change whether the server would return 3780 items corresponding to MIN, MAX, ALL, or COUNT result options. 3782 When the SAVE result option is combined with the MIN or MAX result 3783 option, and both ALL and COUNT result options are absent, the 3784 corresponding MIN/MAX is returned (if the search result is not 3785 empty), but the "$" marker would contain a single message as returned 3786 in the MIN/MAX return item. 3788 If the SAVE result option is combined with both MIN and MAX result 3789 options, and both ALL and COUNT result options are absent, the "$" 3790 marker would contain zero, one or two messages as returned in the 3791 MIN/MAX return items. 3793 If the SAVE result option is combined with the ALL and/or COUNT 3794 result option(s), the "$" marker would always contain all messages 3795 found by the SEARCH or UID SEARCH command. 3797 The following table summarizes the additional requirement on ESEARCH 3798 server implementations described in this section. 3800 +------------------------------+--------------------+ 3801 | Combination of Result option | "$" marker value | 3802 +------------------------------+--------------------+ 3803 | SAVE MIN | MIN | 3804 | SAVE MAX | MAX | 3805 | SAVE MIN MAX | MIN & MAX | 3806 | SAVE * [m] | all found messages | 3807 +------------------------------+--------------------+ 3809 where '*' means "ALL" and/or "COUNT", and '[m]' means optional "MIN" 3810 and/or "MAX" 3812 Implementation note: server implementors should note that "$" can 3813 reference IMAP message sequences or UID sequences, depending on the 3814 context where it is used. For example, the "$" marker can be set as 3815 a result of a SEARCH (SAVE) command and used as a parameter to a UID 3816 FETCH command (which accepts a UID sequence, not a message sequence), 3817 or the "$" marker can be set as a result of a UID SEARCH (SAVE) 3818 command and used as a parameter to a FETCH command (which accepts a 3819 message sequence, not a UID sequence). Server implementations need 3820 to automatically map the "$" marker value to message numbers or UIDs, 3821 depending on context where the "$" marker is used. 3823 6.4.4.2. Multiple Commands in Progress 3825 Use of a SEARCH RETURN (SAVE) command followed by a command using the 3826 "$" marker creates direct dependency between the two commands. As 3827 directed by Section 5.5, a server MUST execute the two commands in 3828 the order they were received. 3830 A client MAY pipeline a SEARCH RETURN (SAVE) command with one or more 3831 command using the "$" marker, as long as this doesn't create an 3832 ambiguity, as described in by Section 5.5. Examples 7-9 in 3833 Section 6.4.4.4 explain this in more details. 3835 6.4.4.3. Refusing to Save Search Results 3837 In some cases, the server MAY refuse to save a SEARCH (SAVE) result, 3838 for example, if an internal limit on the number of saved results is 3839 reached. In this case, the server MUST return a tagged NO response 3840 containing the NOTSAVED response code and set the search result 3841 variable to the empty sequence, as described in Section 6.4.4.1. 3843 6.4.4.4. Examples showing use of SAVE result option 3845 Only in this section: explanatory comments in examples that start 3846 with // are not part of the protocol. 3848 1) The following example demonstrates how the client can use the 3849 result of a SEARCH command to FETCH headers of interesting messages: 3851 Example 1: 3852 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3853 NOT FROM "Smith" 3854 S: A282 OK SEARCH completed, result saved 3855 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3856 S: * 2 FETCH (UID 14 ... 3857 S: * 84 FETCH (UID 100 ... 3858 S: * 882 FETCH (UID 1115 ... 3859 S: A283 OK completed 3861 The client can also pipeline the two commands: 3863 Example 2: 3864 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3865 NOT FROM "Smith" 3866 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3867 S: A282 OK SEARCH completed 3868 S: * 2 FETCH (UID 14 ... 3869 S: * 84 FETCH (UID 100 ... 3870 S: * 882 FETCH (UID 1115 ... 3871 S: A283 OK completed 3873 2) The following example demonstrates that the result of one SEARCH 3874 command can be used as input to another SEARCH command: 3876 Example 3: 3877 C: A300 SEARCH RETURN (SAVE) SINCE 1-Jan-2004 3878 NOT FROM "Smith" 3879 S: A300 OK SEARCH completed 3880 C: A301 UID SEARCH UID $ SMALLER 4096 3881 S: * ESEARCH (TAG "A301") UID ALL 17,900,901 3882 S: A301 OK completed 3884 Note that the second command in Example 3 can be replaced with: 3885 C: A301 UID SEARCH $ SMALLER 4096 3886 and the result of the command would be the same. 3888 3) The following example shows that the "$" marker can be combined 3889 with other message numbers using the OR SEARCH criterion. 3891 Example 4: 3892 C: P282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3893 NOT FROM "Smith" 3894 S: P282 OK SEARCH completed 3895 C: P283 SEARCH CHARSET UTF-8 (OR $ 1,3000:3021) TEXT {8} 3896 C: YYYYYYYY 3897 S: * ESEARCH (TAG "P283") ALL 882,1102,3003,3005:3006 3898 S: P283 OK completed 3900 Note: Since this document format is restricted to 7-bit ASCII text, 3901 it is not possible to show actual UTF-8 data. The "YYYYYYYY" is a 3902 placeholder for what would be 8 octets of 8-bit data in an actual 3903 transaction. 3905 4) The following example demonstrates that a failed SEARCH sets the 3906 search result variable to the empty list. The server doesn't 3907 implement the KOI8-R charset. 3909 Example 5: 3910 C: B282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3911 NOT FROM "Smith" 3912 S: B282 OK SEARCH completed 3913 C: B283 SEARCH RETURN (SAVE) CHARSET KOI8-R 3914 (OR $ 1,3000:3021) TEXT {4} 3915 C: XXXX 3916 S: B283 NO [BADCHARSET UTF-8] KOI8-R is not supported 3917 //After this command the saved result variable contains 3918 //no messages. A client that wants to reissue the B283 3919 //SEARCH command with another CHARSET would have to reissue 3920 //the B282 command as well. One possible workaround for 3921 //this is to include the desired CHARSET parameter 3922 //in the earliest SEARCH RETURN (SAVE) command in a 3923 //sequence of related SEARCH commands, to cause 3924 //the earliest SEARCH in the sequence to fail. 3925 //A better approach might be to always use CHARSET UTF-8 3926 //instead. 3928 Note: Since this document format is restricted to 7-bit ASCII text, 3929 it is not possible to show actual KOI8-R data. The "XXXX" is a 3930 placeholder for what would be 4 octets of 8-bit data in an actual 3931 transaction. 3933 5) The following example demonstrates that it is not an error to use 3934 the "$" marker when it contains no messages. 3936 Example 6: 3937 C: E282 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3938 NOT FROM "Eric" 3939 C: E283 COPY $ "Other Messages" 3940 //The "$" contains no messages 3941 S: E282 OK SEARCH completed 3942 S: E283 OK COPY completed, nothing copied 3944 Example 7: 3945 C: F282 SEARCH RETURN (SAVE) KEYWORD $Junk 3946 C: F283 COPY $ "Junk" 3947 C: F284 STORE $ +FLAGS.Silent (\Deleted) 3948 S: F282 OK SEARCH completed 3949 S: F283 OK COPY completed 3950 S: F284 OK STORE completed 3952 Example 8: 3953 C: G282 SEARCH RETURN (SAVE) KEYWORD $Junk 3954 C: G283 SEARCH RETURN (ALL) SINCE 28-Oct-2006 3955 FROM "Eric" 3956 // The server can execute the two SEARCH commands 3957 // in any order, as they don't have any dependency. 3958 // For example, it may return: 3959 S: * ESEARCH (TAG "G283") ALL 3:15,27,29:103 3960 S: G283 OK SEARCH completed 3961 S: G282 OK SEARCH completed 3963 The following example demonstrates that the result of the second 3964 SEARCH RETURN (SAVE) always overrides the result of the first. 3966 Example 9: 3967 C: H282 SEARCH RETURN (SAVE) KEYWORD $Junk 3968 C: H283 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3969 FROM "Eric" 3970 S: H282 OK SEARCH completed 3971 S: H283 OK SEARCH completed 3972 // At this point "$" would contain results of H283 3974 The following example demonstrates behavioral difference for 3975 different combinations of ESEARCH result options. 3977 Example 10: 3978 C: C282 SEARCH RETURN (ALL) SINCE 12-Feb-2006 3979 NOT FROM "Smith" 3980 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3981 //$ value hasn't changed 3982 S: C282 OK SEARCH completed 3984 C: C283 SEARCH RETURN (ALL SAVE) SINCE 12-Feb-2006 3985 NOT FROM "Smith" 3986 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3987 //$ value is 2,10:15,21 3988 S: C283 OK SEARCH completed 3990 C: C284 SEARCH RETURN (SAVE MIN) SINCE 12-Feb-2006 3991 NOT FROM "Smith" 3992 S: * ESEARCH (TAG "C284") MIN 2 3993 //$ value is 2 3994 S: C284 OK SEARCH completed 3996 C: C285 SEARCH RETURN (MAX SAVE MIN) SINCE 3997 12-Feb-2006 NOT FROM "Smith" 3998 S: * ESEARCH (TAG "C285") MIN 2 MAX 21 3999 //$ value is 2,21 4000 S: C285 OK SEARCH completed 4002 C: C286 SEARCH RETURN (MAX SAVE MIN COUNT) 4003 SINCE 12-Feb-2006 NOT FROM "Smith" 4004 S: * ESEARCH (TAG "C286") MIN 2 MAX 21 COUNT 8 4005 //$ value is 2,10:15,21 4006 S: C286 OK SEARCH completed 4008 C: C286 SEARCH RETURN (ALL SAVE MIN) SINCE 4009 12-Feb-2006 NOT FROM "Smith" 4010 S: * ESEARCH (TAG "C286") MIN 2 ALL 2,10:15,21 4011 //$ value is 2,10:15,21 4012 S: C286 OK SEARCH completed 4014 6.4.5. FETCH Command 4016 Arguments: sequence set 4017 message data item names or macro 4019 Responses: untagged responses: FETCH 4021 Result: OK - fetch completed 4022 NO - fetch error: can't fetch that data 4023 BAD - command unknown or arguments invalid 4025 The FETCH command retrieves data associated with a message in the 4026 mailbox. The data items to be fetched can be either a single atom or 4027 a parenthesized list. 4029 Most data items, identified in the formal syntax under the msg-att- 4030 static rule, are static and MUST NOT change for any particular 4031 message. Other data items, identified in the formal syntax under the 4032 msg-att-dynamic rule, MAY change, either as a result of a STORE 4033 command or due to external events. 4035 For example, if a client receives an ENVELOPE for a message when 4036 it already knows the envelope, it can safely ignore the newly 4037 transmitted envelope. 4039 There are three macros which specify commonly-used sets of data 4040 items, and can be used instead of data items. A macro must be used 4041 by itself, and not in conjunction with other macros or data items. 4043 ALL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE) 4045 FAST Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE) 4047 FULL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE 4048 BODY) 4050 Several data items reference "section" or "section-binary". See 4051 Section 6.4.5.1 for their detailed definition. 4053 The currently defined data items that can be fetched are: 4055 BINARY[]<> 4057 Requests that the specified section be transmitted after 4058 performing Content-Transfer-Encoding-related decoding. 4060 The argument, if present, requests that a subset of 4061 the data be returned. The semantics of a partial FETCH BINARY 4062 command are the same as for a partial FETCH BODY command, with 4063 the exception that the arguments refer to the DECODED 4064 section data. 4066 Note that this data item can only be requested for leaf (i.e. 4067 non multipart/*, non message/rfc822 and non message/global) 4068 body parts. 4070 BINARY.PEEK[]<> An alternate form of 4071 BINARY[] that does not implicitly set the \Seen 4072 flag. 4074 BINARY.SIZE[] 4076 Requests the decoded size of the section (i.e., the size to 4077 expect in response to the corresponding FETCH BINARY request). 4079 Note: client authors are cautioned that this might be an 4080 expensive operation for some server implementations. 4081 Needlessly issuing this request could result in degraded 4082 performance due to servers having to calculate the value every 4083 time the request is issued. 4085 Note that this data item can only be requested for leaf (i.e. 4086 non multipart/*, non message/rfc822 and non message/global) 4087 body parts. 4089 BODY Non-extensible form of BODYSTRUCTURE. 4091 BODY[
]<> 4093 The text of a particular body section. 4095 It is possible to fetch a substring of the designated text. 4096 This is done by appending an open angle bracket ("<"), the 4097 octet position of the first desired octet, a period, the 4098 maximum number of octets desired, and a close angle bracket 4099 (">") to the part specifier. If the starting octet is beyond 4100 the end of the text, an empty string is returned. 4102 Any partial fetch that attempts to read beyond the end of the 4103 text is truncated as appropriate. A partial fetch that starts 4104 at octet 0 is returned as a partial fetch, even if this 4105 truncation happened. 4107 Note: This means that BODY[]<0.2048> of a 1500-octet message 4108 will return BODY[]<0> with a literal of size 1500, not 4109 BODY[]. 4111 Note: A substring fetch of a HEADER.FIELDS or 4112 HEADER.FIELDS.NOT part specifier is calculated after 4113 subsetting the header. 4115 The \Seen flag is implicitly set; if this causes the flags to 4116 change, they SHOULD be included as part of the FETCH responses. 4118 BODY.PEEK[
]<> An alternate form of BODY[
] 4119 that does not implicitly set the \Seen flag. 4121 BODYSTRUCTURE The [MIME-IMB] body structure of the message. This is 4122 computed by the server by parsing the [MIME-IMB] header fields in 4123 the [RFC-5322] header and [MIME-IMB] headers. See Section 7.4.2 4124 for more details. 4126 ENVELOPE The envelope structure of the message. This is computed by 4127 the server by parsing the [RFC-5322] header into the component 4128 parts, defaulting various fields as necessary. See Section 7.4.2 4129 for more details. 4131 FLAGS The flags that are set for this message. 4133 INTERNALDATE The internal date of the message. 4135 RFC822.SIZE The [RFC-5322] size of the message. 4137 UID The unique identifier for the message. 4139 Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)]) 4140 S: * 2 FETCH .... 4141 S: * 3 FETCH .... 4142 S: * 4 FETCH .... 4143 S: A654 OK FETCH completed 4145 6.4.5.1. FETCH section specification 4147 Several FETCH data items reference "section" or "section-binary". 4148 The section specification is a set of zero or more part specifiers 4149 delimited by periods. A part specifier is either a part number or 4150 one of the following: HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, 4151 and TEXT. (Non numeric part specifiers have to be the last specifier 4152 in a section specification.) An empty section specification refers 4153 to the entire message, including the header. 4155 Every message has at least one part number. Non-[MIME-IMB] messages, 4156 and non-multipart [MIME-IMB] messages with no encapsulated message, 4157 only have a part 1. 4159 Multipart messages are assigned consecutive part numbers, as they 4160 occur in the message. If a particular part is of type message or 4161 multipart, its parts MUST be indicated by a period followed by the 4162 part number within that nested multipart part. 4164 A part of type MESSAGE/RFC822 or MESSAGE/GLOBAL also has nested part 4165 numbers, referring to parts of the MESSAGE part's body. 4167 The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part 4168 specifiers can be the sole part specifier or can be prefixed by one 4169 or more numeric part specifiers, provided that the numeric part 4170 specifier refers to a part of type MESSAGE/RFC822 or MESSAGE/GLOBAL. 4171 The MIME part specifier MUST be prefixed by one or more numeric part 4172 specifiers. 4174 The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part specifiers 4175 refer to the [RFC-5322] header of the message or of an encapsulated 4176 [MIME-IMT] MESSAGE/RFC822 or MESSAGE/GLOBAL message. HEADER.FIELDS 4177 and HEADER.FIELDS.NOT are followed by a list of field-name (as 4178 defined in [RFC-5322]) names, and return a subset of the header. The 4179 subset returned by HEADER.FIELDS contains only those header fields 4180 with a field-name that matches one of the names in the list; 4181 similarly, the subset returned by HEADER.FIELDS.NOT contains only the 4182 header fields with a non-matching field-name. The field-matching is 4183 ASCII range case-insensitive but otherwise exact. Subsetting does 4184 not exclude the [RFC-5322] delimiting blank line between the header 4185 and the body; the blank line is included in all header fetches, 4186 except in the case of a message which has no body and no blank line. 4188 The MIME part specifier refers to the [MIME-IMB] header for this 4189 part. 4191 The TEXT part specifier refers to the text body of the message, 4192 omitting the [RFC-5322] header. 4194 Here is an example of a complex message with some of its part 4195 specifiers: 4197 HEADER ([RFC-5322] header of the message) 4198 TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4199 1 TEXT/PLAIN 4200 2 APPLICATION/OCTET-STREAM 4201 3 MESSAGE/RFC822 4202 3.HEADER ([RFC-5322] header of the message) 4203 3.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4204 3.1 TEXT/PLAIN 4205 3.2 APPLICATION/OCTET-STREAM 4206 4 MULTIPART/MIXED 4207 4.1 IMAGE/GIF 4208 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF) 4209 4.2 MESSAGE/RFC822 4210 4.2.HEADER ([RFC-5322] header of the message) 4211 4.2.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4212 4.2.1 TEXT/PLAIN 4213 4.2.2 MULTIPART/ALTERNATIVE 4214 4.2.2.1 TEXT/PLAIN 4215 4.2.2.2 TEXT/RICHTEXT 4217 6.4.6. STORE Command 4219 Arguments: sequence set 4220 message data item name 4221 value for message data item 4223 Responses: untagged responses: FETCH 4225 Result: OK - store completed 4226 NO - store error: can't store that data 4227 BAD - command unknown or arguments invalid 4229 The STORE command alters data associated with a message in the 4230 mailbox. Normally, STORE will return the updated value of the data 4231 with an untagged FETCH response. A suffix of ".SILENT" in the data 4232 item name prevents the untagged FETCH, and the server SHOULD assume 4233 that the client has determined the updated value itself or does not 4234 care about the updated value. 4236 Note: Regardless of whether or not the ".SILENT" suffix was used, 4237 the server SHOULD send an untagged FETCH response if a change to a 4238 message's flags from an external source is observed. The intent 4239 is that the status of the flags is determinate without a race 4240 condition. 4242 The currently defined data items that can be stored are: 4244 FLAGS Replace the flags for the message with the 4245 argument. The new value of the flags is returned as if a FETCH of 4246 those flags was done. 4248 FLAGS.SILENT Equivalent to FLAGS, but without returning 4249 a new value. 4251 +FLAGS Add the argument to the flags for the message. 4252 The new value of the flags is returned as if a FETCH of those 4253 flags was done. 4255 +FLAGS.SILENT Equivalent to +FLAGS, but without 4256 returning a new value. 4258 -FLAGS Remove the argument from the flags for the 4259 message. The new value of the flags is returned as if a FETCH of 4260 those flags was done. 4262 -FLAGS.SILENT Equivalent to -FLAGS, but without 4263 returning a new value. 4265 Example: C: A003 STORE 2:4 +FLAGS (\Deleted) 4266 S: * 2 FETCH (FLAGS (\Deleted \Seen)) 4267 S: * 3 FETCH (FLAGS (\Deleted)) 4268 S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen)) 4269 S: A003 OK STORE completed 4271 6.4.7. COPY Command 4273 Arguments: sequence set 4274 mailbox name 4276 Responses: no specific responses for this command 4278 Result: OK - copy completed 4279 NO - copy error: can't copy those messages or to that 4280 name 4281 BAD - command unknown or arguments invalid 4283 The COPY command copies the specified message(s) to the end of the 4284 specified destination mailbox. The flags and internal date of the 4285 message(s) SHOULD be preserved in the copy. 4287 If the destination mailbox does not exist, a server SHOULD return an 4288 error. It SHOULD NOT automatically create the mailbox. Unless it is 4289 certain that the destination mailbox can not be created, the server 4290 MUST send the response code "[TRYCREATE]" as the prefix of the text 4291 of the tagged NO response. This gives a hint to the client that it 4292 can attempt a CREATE command and retry the COPY if the CREATE is 4293 successful. 4295 If the COPY command is unsuccessful for any reason, server 4296 implementations MUST restore the destination mailbox to its state 4297 before the COPY attempt. 4299 On successful completion of a COPY, the server SHOULD return a 4300 COPYUID response code (see Section 7.1). 4302 In the case of a mailbox that has permissions set so that the client 4303 can COPY to the mailbox, but not SELECT or EXAMINE it, the server 4304 SHOULD NOT send an COPYUID response code as it would disclose 4305 information about the mailbox. 4307 In the case of a mailbox that has UIDNOTSTICKY status (see 4308 Section 7.1), the server MAY omit the COPYUID response code as it is 4309 not meaningful. 4311 If the server does not return the COPYUID response code, the client 4312 can discover this information by selecting the destination mailbox. 4314 The location of messages placed in the destination mailbox by COPY 4315 can be determined by using FETCH and/or SEARCH commands (e.g., for 4316 Message-ID). 4318 Example: C: A003 COPY 2:4 MEETING 4319 S: A003 OK COPY completed 4321 6.4.8. MOVE Command 4323 Arguments: sequence set 4324 mailbox name 4326 Responses: no specific responses for this command 4328 Result: OK - move completed 4329 NO - move error: can't move those messages or to that 4330 name 4331 BAD - command unknown or arguments invalid 4333 The MOVE command moves the specified message(s) to the end of the 4334 specified destination mailbox. The flags and internal date of the 4335 message(s) SHOULD be preserved. 4337 This means that a new message is created in the target mailbox with a 4338 new UID, the original message is removed from the source mailbox, and 4339 it appears to the client as a single action. This has the same 4340 effect for each message as this sequence: 4342 1. [UID] COPY 4344 2. [UID] STORE +FLAGS.SILENT \DELETED 4346 3. UID EXPUNGE 4348 Although the effect of the MOVE is the same as the preceding steps, 4349 the semantics are not identical: The intermediate states produced by 4350 those steps do not occur, and the response codes are different. In 4351 particular, though the COPY and EXPUNGE response codes will be 4352 returned, response codes for a STORE MUST NOT be generated and the 4353 \Deleted flag MUST NOT be set for any message. 4355 Because a MOVE applies to a set of messages, it might fail partway 4356 through the set. Regardless of whether the command is successful in 4357 moving the entire set, each individual message SHOULD either be moved 4358 or unaffected. The server MUST leave each message in a state where 4359 it is in at least one of the source or target mailboxes (no message 4360 can be lost or orphaned). The server SHOULD NOT leave any message in 4361 both mailboxes (it would be bad for a partial failure to result in a 4362 bunch of duplicate messages). This is true even if the server 4363 returns a tagged NO response to the command. 4365 Because of the similarity of MOVE to COPY, extensions that affect 4366 COPY affect MOVE in the same way. Response codes such as TRYCREATE 4367 (see Section 7.1), as well as those defined by extensions, are sent 4368 as appropriate. 4370 Servers SHOULD send COPYUID in response to a UID MOVE (see 4371 Section 6.4.9) command. For additional information see Section 7.1. 4373 Servers are also advised to send the COPYUID response code in an 4374 untagged OK before sending EXPUNGE or moved responses. (Sending 4375 COPYUID in the tagged OK, as described in the UIDPLUS specification, 4376 means that clients first receive an EXPUNGE for a message and 4377 afterwards COPYUID for the same message. It can be unnecessarily 4378 difficult to process that sequence usefully.) 4380 An example: 4381 C: a UID MOVE 42:69 foo 4382 S: * OK [COPYUID 432432 42:69 1202:1229] 4383 S: * 22 EXPUNGE 4384 S: (more expunges) 4385 S: a OK Done 4387 Note that the server may send unrelated EXPUNGE responses as well, if 4388 any happen to have been expunged at the same time; this is normal 4389 IMAP operation. 4391 Note that moving a message to the currently selected mailbox (that 4392 is, where the source and target mailboxes are the same) is allowed 4393 when copying the message to the currently selected mailbox is 4394 allowed. 4396 The server may send EXPUNGE responses before the tagged response, so 4397 the client cannot safely send more commands with message sequence 4398 number arguments while the server is processing MOVE. 4400 MOVE and UID MOVE can be pipelined with other commands, but care has 4401 to be taken. Both commands modify sequence numbers and also allow 4402 unrelated EXPUNGE responses. The renumbering of other messages in 4403 the source mailbox following any EXPUNGE response can be surprising 4404 and makes it unsafe to pipeline any command that relies on message 4405 sequence numbers after a MOVE or UID MOVE. Similarly, MOVE cannot be 4406 pipelined with a command that might cause message renumbering. See 4407 Section 5.5, for more information about ambiguities as well as 4408 handling requirements for both clients and servers. 4410 6.4.9. UID Command 4412 Arguments: command name 4413 command arguments 4415 Responses: untagged responses: FETCH, ESEARCH, EXPUNGE 4417 Result: OK - UID command completed 4418 NO - UID command error 4419 BAD - command unknown or arguments invalid 4421 The UID command has three forms. In the first form, it takes as its 4422 arguments a COPY, MOVE, FETCH, or STORE command with arguments 4423 appropriate for the associated command. However, the numbers in the 4424 sequence set argument are unique identifiers instead of message 4425 sequence numbers. Sequence set ranges are permitted, but there is no 4426 guarantee that unique identifiers will be contiguous. 4428 A non-existent unique identifier is ignored without any error message 4429 generated. Thus, it is possible for a UID FETCH command to return an 4430 OK without any data or a UID COPY, UID MOVE or UID STORE to return an 4431 OK without performing any operations. 4433 In the second form, the UID command takes an EXPUNGE command with an 4434 extra parameter the specified a sequence set of UIDs to operate on. 4435 The UID EXPUNGE command permanently removes all messages that both 4436 have the \Deleted flag set and have a UID that is included in the 4437 specified sequence set from the currently selected mailbox. If a 4438 message either does not have the \Deleted flag set or has a UID that 4439 is not included in the specified sequence set, it is not affected. 4441 UID EXPUNGE is particularly useful for disconnected use clients. 4442 By using UID EXPUNGE instead of EXPUNGE when resynchronizing with 4443 the server, the client can ensure that it does not inadvertantly 4444 remove any messages that have been marked as \Deleted by other 4445 clients between the time that the client was last connected and 4446 the time the client resynchronizes. 4448 Example: C: A003 UID EXPUNGE 3000:3002 4449 S: * 3 EXPUNGE 4450 S: * 3 EXPUNGE 4451 S: * 3 EXPUNGE 4452 S: A003 OK UID EXPUNGE completed 4454 In the third form, the UID command takes a SEARCH command with SEARCH 4455 command arguments. The interpretation of the arguments is the same 4456 as with SEARCH; however, the numbers returned in a ESEARCH response 4457 for a UID SEARCH command are unique identifiers instead of message 4458 sequence numbers. Also, the corresponding ESEARCH response MUST 4459 include the UID indicator. For example, the command UID SEARCH 1:100 4460 UID 443:557 returns the unique identifiers corresponding to the 4461 intersection of two sequence sets, the message sequence number range 4462 1:100 and the UID range 443:557. 4464 Note: in the above example, the UID range 443:557 appears. The 4465 same comment about a non-existent unique identifier being ignored 4466 without any error message also applies here. Hence, even if 4467 neither UID 443 or 557 exist, this range is valid and would 4468 include an existing UID 495. 4470 Also note that a UID range of 559:* always includes the UID of the 4471 last message in the mailbox, even if 559 is higher than any 4472 assigned UID value. This is because the contents of a range are 4473 independent of the order of the range endpoints. Thus, any UID 4474 range with * as one of the endpoints indicates at least one 4475 message (the message with the highest numbered UID), unless the 4476 mailbox is empty. 4478 The number after the "*" in an untagged FETCH or EXPUNGE response is 4479 always a message sequence number, not a unique identifier, even for a 4480 UID command response. However, server implementations MUST 4481 implicitly include the UID message data item as part of any FETCH 4482 response caused by a UID command, regardless of whether a UID was 4483 specified as a message data item to the FETCH. 4485 Note: The rule about including the UID message data item as part of a 4486 FETCH response primarily applies to the UID FETCH and UID STORE 4487 commands, including a UID FETCH command that does not include UID as 4488 a message data item. Although it is unlikely that the other UID 4489 commands will cause an untagged FETCH, this rule applies to these 4490 commands as well. 4492 Example: C: A999 UID FETCH 4827313:4828442 FLAGS 4493 S: * 23 FETCH (FLAGS (\Seen) UID 4827313) 4494 S: * 24 FETCH (FLAGS (\Seen) UID 4827943) 4495 S: * 25 FETCH (FLAGS (\Seen) UID 4828442) 4496 S: A999 OK UID FETCH completed 4498 6.5. Client Commands - Experimental/Expansion 4500 6.5.1. X Command 4502 Arguments: implementation defined 4504 Responses: implementation defined 4505 Result: OK - command completed 4506 NO - failure 4507 BAD - command unknown or arguments invalid 4509 Any command prefixed with an X is an experimental command. Commands 4510 which are not part of this specification, a standard or standards- 4511 track revision of this specification, or an IESG-approved 4512 experimental protocol, MUST use the X prefix. 4514 Any added untagged responses issued by an experimental command MUST 4515 also be prefixed with an X. Server implementations MUST NOT send any 4516 such untagged responses, unless the client requested it by issuing 4517 the associated experimental command. 4519 Example: C: a441 CAPABILITY 4520 S: * CAPABILITY IMAP4rev2 XPIG-LATIN 4521 S: a441 OK CAPABILITY completed 4522 C: A442 XPIG-LATIN 4523 S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay 4524 S: A442 OK XPIG-LATIN ompleted-cay 4526 7. Server Responses 4528 Server responses are in three forms: status responses, server data, 4529 and command continuation request. The information contained in a 4530 server response, identified by "Contents:" in the response 4531 descriptions below, is described by function, not by syntax. The 4532 precise syntax of server responses is described in the Formal Syntax 4533 section. 4535 The client MUST be prepared to accept any response at all times. 4537 Status responses can be tagged or untagged. Tagged status responses 4538 indicate the completion result (OK, NO, or BAD status) of a client 4539 command, and have a tag matching the command. 4541 Some status responses, and all server data, are untagged. An 4542 untagged response is indicated by the token "*" instead of a tag. 4543 Untagged status responses indicate server greeting, or server status 4544 that does not indicate the completion of a command (for example, an 4545 impending system shutdown alert). For historical reasons, untagged 4546 server data responses are also called "unsolicited data", although 4547 strictly speaking, only unilateral server data is truly 4548 "unsolicited". 4550 Certain server data MUST be recorded by the client when it is 4551 received; this is noted in the description of that data. Such data 4552 conveys critical information which affects the interpretation of all 4553 subsequent commands and responses (e.g., updates reflecting the 4554 creation or destruction of messages). 4556 Other server data SHOULD be recorded for later reference; if the 4557 client does not need to record the data, or if recording the data has 4558 no obvious purpose (e.g., a SEARCH response when no SEARCH command is 4559 in progress), the data SHOULD be ignored. 4561 An example of unilateral untagged server data occurs when the IMAP 4562 connection is in the selected state. In the selected state, the 4563 server checks the mailbox for new messages as part of command 4564 execution. Normally, this is part of the execution of every command; 4565 hence, a NOOP command suffices to check for new messages. If new 4566 messages are found, the server sends untagged EXISTS response 4567 reflecting the new size of the mailbox. Server implementations that 4568 offer multiple simultaneous access to the same mailbox SHOULD also 4569 send appropriate unilateral untagged FETCH and EXPUNGE responses if 4570 another agent changes the state of any message flags or expunges any 4571 messages. 4573 Command continuation request responses use the token "+" instead of a 4574 tag. These responses are sent by the server to indicate acceptance 4575 of an incomplete client command and readiness for the remainder of 4576 the command. 4578 7.1. Server Responses - Status Responses 4580 Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD 4581 can be tagged or untagged. PREAUTH and BYE are always untagged. 4583 Status responses MAY include an OPTIONAL "response code". A response 4584 code consists of data inside square brackets in the form of an atom, 4585 possibly followed by a space and arguments. The response code 4586 contains additional information or status codes for client software 4587 beyond the OK/NO/BAD condition, and are defined when there is a 4588 specific action that a client can take based upon the additional 4589 information. 4591 The currently defined response codes are: 4593 ALERT 4595 The human-readable text contains a special alert that MUST be 4596 presented to the user in a fashion that calls the user's 4597 attention to the message. 4599 ALREADYEXISTS 4600 The operation attempts to create something that already exists, 4601 such as when the CREATE or RENAME directories attempt to create 4602 a mailbox and there is already one of that name. 4604 C: o356 RENAME this that 4605 S: o356 NO [ALREADYEXISTS] Mailbox "that" already exists 4607 APPENDUID 4609 Followed by the UIDVALIDITY of the destination mailbox and the 4610 UID assigned to the appended message in the destination 4611 mailbox, indicates that the message has been appended to the 4612 destination mailbox with that UID. 4614 If the server also supports the [MULTIAPPEND] extension, and if 4615 multiple messages were appended in the APPEND command, then the 4616 second value is a UID set containing the UIDs assigned to the 4617 appended messages, in the order they were transmitted in the 4618 APPEND command. This UID set may not contain extraneous UIDs 4619 or the symbol "*". 4621 Note: the UID set form of the APPENDUID response code MUST 4622 NOT be used if only a single message was appended. In 4623 particular, a server MUST NOT send a range such as 123:123. 4624 This is because a client that does not support [MULTIAPPEND] 4625 expects only a single UID and not a UID set. 4627 UIDs are assigned in strictly ascending order in the mailbox 4628 (refer to Section 2.3.1.1); note that a range of 12:10 is 4629 exactly equivalent to 10:12 and refers to the sequence 4630 10,11,12. 4632 This response code is returned in a tagged OK response to the 4633 APPEND command. 4635 AUTHENTICATIONFAILED 4637 Authentication failed for some reason on which the server is 4638 unwilling to elaborate. Typically, this includes "unknown 4639 user" and "bad password". 4641 This is the same as not sending any response code, except that 4642 when a client sees AUTHENTICATIONFAILED, it knows that the 4643 problem wasn't, e.g., UNAVAILABLE, so there's no point in 4644 trying the same login/password again later. 4646 C: b LOGIN "fred" "foo" 4647 S: b NO [AUTHENTICATIONFAILED] Authentication failed 4649 AUTHORIZATIONFAILED 4651 Authentication succeeded in using the authentication identity, 4652 but the server cannot or will not allow the authentication 4653 identity to act as the requested authorization identity. This 4654 is only applicable when the authentication and authorization 4655 identities are different. 4657 C: c1 AUTHENTICATE PLAIN 4658 [...] 4659 S: c1 NO [AUTHORIZATIONFAILED] No such authorization-ID 4661 C: c2 AUTHENTICATE PLAIN 4662 [...] 4663 S: c2 NO [AUTHORIZATIONFAILED] Authenticator is not an admin 4665 BADCHARSET 4667 Optionally followed by a parenthesized list of charsets. A 4668 SEARCH failed because the given charset is not supported by 4669 this implementation. If the optional list of charsets is 4670 given, this lists the charsets that are supported by this 4671 implementation. 4673 CANNOT 4675 The operation violates some invariant of the server and can 4676 never succeed. 4678 C: l create "///////" 4679 S: l NO [CANNOT] Adjacent slashes are not supported 4681 CAPABILITY 4683 Followed by a list of capabilities. This can appear in the 4684 initial OK or PREAUTH response to transmit an initial 4685 capabilities list. It can also appear in tagged responses to 4686 LOGIN or AUTHENTICATE commands. This makes it unnecessary for 4687 a client to send a separate CAPABILITY command if it recognizes 4688 this response. 4690 CLIENTBUG 4691 The server has detected a client bug. This can accompany all 4692 of OK, NO, and BAD, depending on what the client bug is. 4694 C: k1 select "/archive/projects/experiment-iv" 4695 [...] 4696 S: k1 OK [READ-ONLY] Done 4697 C: k2 status "/archive/projects/experiment-iv" (messages) 4698 [...] 4699 S: k2 OK [CLIENTBUG] Done 4701 CLOSED 4703 The CLOSED response code has no parameters. A server return 4704 the CLOSED response code when the currently selected mailbox is 4705 closed implicitly using the SELECT/EXAMINE command on another 4706 mailbox. The CLOSED response code serves as a boundary between 4707 responses for the previously opened mailbox (which was closed) 4708 and the newly selected mailbox; all responses before the CLOSED 4709 response code relate to the mailbox that was closed, and all 4710 subsequent responses relate to the newly opened mailbox. 4712 There is no need to return the CLOSED response code on 4713 completion of the CLOSE or the UNSELECT command (or similar), 4714 whose purpose is to close the currently selected mailbox 4715 without opening a new one. 4717 CONTACTADMIN 4719 The user should contact the system administrator or support 4720 desk. 4722 C: e login "fred" "foo" 4723 S: e OK [CONTACTADMIN] 4725 COPYUID 4727 Followed by the UIDVALIDITY of the destination mailbox, a UID 4728 set containing the UIDs of the message(s) in the source mailbox 4729 that were copied to the destination mailbox and containing the 4730 UIDs assigned to the copied message(s) in the destination 4731 mailbox, indicates that the message(s) have been copied to the 4732 destination mailbox with the stated UID(s). 4734 The source UID set is in the order the message(s) were copied; 4735 the destination UID set corresponds to the source UID set and 4736 is in the same order. Neither of the UID sets may contain 4737 extraneous UIDs or the symbol "*". 4739 UIDs are assigned in strictly ascending order in the mailbox 4740 (refer to Section 2.3.1.1); note that a range of 12:10 is 4741 exactly equivalent to 10:12 and refers to the sequence 4742 10,11,12. 4744 This response code is returned in a tagged OK response to the 4745 COPY command. 4747 CORRUPTION 4749 The server discovered that some relevant data (e.g., the 4750 mailbox) are corrupt. This response code does not include any 4751 information about what's corrupt, but the server can write that 4752 to its logfiles. 4754 C: i select "/archive/projects/experiment-iv" 4755 S: i NO [CORRUPTION] Cannot open mailbox 4757 EXPIRED 4759 Either authentication succeeded or the server no longer had the 4760 necessary data; either way, access is no longer permitted using 4761 that passphrase. The client or user should get a new 4762 passphrase. 4764 C: d login "fred" "foo" 4765 S: d NO [EXPIRED] That password isn't valid any more 4767 EXPUNGEISSUED 4769 Someone else has issued an EXPUNGE for the same mailbox. The 4770 client may want to issue NOOP soon. [IMAP-MULTIACCESS] 4771 discusses this subject in depth. 4773 C: h search from fred@example.com 4774 S: * ESEARCH (TAG "h") ALL 1:3,5,8,13,21,42 4775 S: h OK [EXPUNGEISSUED] Search completed 4777 HASCHILDREN 4779 The mailbox delete operation failed because the mailbox has one 4780 or more children and the server doesn't allow deletion of 4781 mailboxes with children. 4783 C: m356 DELETE Notes 4784 S: o356 NO [HASCHILDREN] Mailbox "Notes" has children that need 4785 to be deleted first 4787 INUSE 4789 An operation has not been carried out because it involves 4790 sawing off a branch someone else is sitting on. Someone else 4791 may be holding an exclusive lock needed for this operation, or 4792 the operation may involve deleting a resource someone else is 4793 using, typically a mailbox. 4795 The operation may succeed if the client tries again later. 4797 C: g delete "/archive/projects/experiment-iv" 4798 S: g NO [INUSE] Mailbox in use 4800 LIMIT 4802 The operation ran up against an implementation limit of some 4803 kind, such as the number of flags on a single message or the 4804 number of flags used in a mailbox. 4806 C: m STORE 42 FLAGS f1 f2 f3 f4 f5 ... f250 4807 S: m NO [LIMIT] At most 32 flags in one mailbox supported 4809 NONEXISTENT 4811 The operation attempts to delete something that does not exist. 4812 Similar to ALREADYEXISTS. 4814 C: p RENAME this that 4815 S: p NO [NONEXISTENT] No such mailbox 4817 NOPERM 4819 The access control system (e.g., Access Control List (ACL), see 4820 [RFC4314] does not permit this user to carry out an operation, 4821 such as selecting or creating a mailbox. 4823 C: f select "/archive/projects/experiment-iv" 4824 S: f NO [NOPERM] Access denied 4826 OVERQUOTA 4828 The user would be over quota after the operation. (The user 4829 may or may not be over quota already.) 4831 Note that if the server sends OVERQUOTA but doesn't support the 4832 IMAP QUOTA extension defined by [RFC2087], then there is a 4833 quota, but the client cannot find out what the quota is. 4835 C: n1 uid copy 1:* oldmail 4836 S: n1 NO [OVERQUOTA] Sorry 4838 C: n2 uid copy 1:* oldmail 4839 S: n2 OK [OVERQUOTA] You are now over your soft quota 4841 PARSE 4843 The human-readable text represents an error in parsing the 4844 [RFC-5322] header or [MIME-IMB] headers of a message in the 4845 mailbox. 4847 PERMANENTFLAGS 4849 Followed by a parenthesized list of flags, indicates which of 4850 the known flags the client can change permanently. Any flags 4851 that are in the FLAGS untagged response, but not the 4852 PERMANENTFLAGS list, can not be set permanently. The 4853 PERMANENTFLAGS list can also include the special flag \*, which 4854 indicates that it is possible to create new keywords by 4855 attempting to store those keywords in the mailbox. If the 4856 client attempts to STORE a flag that is not in the 4857 PERMANENTFLAGS list, the server will either ignore the change 4858 or store the state change for the remainder of the current 4859 session only. 4861 There is no need for a server that included the special flag \* 4862 to return a new PERMANENTFLAGS response code when a new keyword 4863 was successfully set on a message upon client request. However 4864 if the server has a limit on the number of different keywords 4865 that can be stored in a mailbox and that limit is reached, the 4866 server MUST send a new PERMANENTFLAGS response code without the 4867 special flag \*. 4869 PRIVACYREQUIRED 4871 The operation is not permitted due to a lack of privacy. If 4872 Transport Layer Security (TLS) is not in use, the client could 4873 try STARTTLS (see Section 6.2.1) and then repeat the operation. 4875 C: d login "fred" "foo" 4876 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4878 C: d select inbox 4879 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4881 READ-ONLY 4883 The mailbox is selected read-only, or its access while selected 4884 has changed from read-write to read-only. 4886 READ-WRITE 4888 The mailbox is selected read-write, or its access while 4889 selected has changed from read-only to read-write. 4891 SERVERBUG 4893 The server encountered a bug in itself or violated one of its 4894 own invariants. 4896 C: j select "/archive/projects/experiment-iv" 4897 S: j NO [SERVERBUG] This should not happen 4899 TRYCREATE 4901 An APPEND or COPY attempt is failing because the target mailbox 4902 does not exist (as opposed to some other reason). This is a 4903 hint to the client that the operation can succeed if the 4904 mailbox is first created by the CREATE command. 4906 UIDNEXT 4908 Followed by a decimal number, indicates the next unique 4909 identifier value. Refer to Section 2.3.1.1 for more 4910 information. 4912 UIDNOTSTICKY 4914 The selected mailbox is supported by a mail store that does not 4915 support persistent UIDs; that is, UIDVALIDITY will be different 4916 each time the mailbox is selected. Consequently, APPEND or 4917 COPY to this mailbox will not return an APPENDUID or COPYUID 4918 response code. 4920 This response code is returned in an untagged NO response to 4921 the SELECT command. 4923 Note: servers SHOULD NOT have any UIDNOTSTICKY mail stores. 4924 This facility exists to support legacy mail stores in which 4925 it is technically infeasible to support persistent UIDs. 4926 This should be avoided when designing new mail stores. 4928 UIDVALIDITY 4930 Followed by a decimal number, indicates the unique identifier 4931 validity value. Refer to Section 2.3.1.1 for more information. 4933 UNAVAILABLE 4935 Temporary failure because a subsystem is down. For example, an 4936 IMAP server that uses a Lightweight Directory Access Protocol 4937 (LDAP) or Radius server for authentication might use this 4938 response code when the LDAP/Radius server is down. 4940 C: a LOGIN "fred" "foo" 4941 S: a NO [UNAVAILABLE] User's backend down for maintenance 4943 UNKNOWN-CTE 4945 The server does not know how to decode the section's Content- 4946 Transfer-Encoding. 4948 Client implementations MUST ignore response codes that they do not 4949 recognize. 4951 7.1.1. OK Response 4953 Contents: OPTIONAL response code 4954 human-readable text 4956 The OK response indicates an information message from the server. 4957 When tagged, it indicates successful completion of the associated 4958 command. The human-readable text MAY be presented to the user as an 4959 information message. The untagged form indicates an information-only 4960 message; the nature of the information MAY be indicated by a response 4961 code. 4963 The untagged form is also used as one of three possible greetings at 4964 connection startup. It indicates that the connection is not yet 4965 authenticated and that a LOGIN or an AUTHENTICATE command is needed. 4967 Example: S: * OK IMAP4rev2 server ready 4968 C: A001 LOGIN fred blurdybloop 4969 S: * OK [ALERT] System shutdown in 10 minutes 4970 S: A001 OK LOGIN Completed 4972 7.1.2. NO Response 4974 Contents: OPTIONAL response code 4975 human-readable text 4977 The NO response indicates an operational error message from the 4978 server. When tagged, it indicates unsuccessful completion of the 4979 associated command. The untagged form indicates a warning; the 4980 command can still complete successfully. The human-readable text 4981 describes the condition. 4983 Example: C: A222 COPY 1:2 owatagusiam 4984 S: * NO Disk is 98% full, please delete unnecessary data 4985 S: A222 OK COPY completed 4986 C: A223 COPY 3:200 blurdybloop 4987 S: * NO Disk is 98% full, please delete unnecessary data 4988 S: * NO Disk is 99% full, please delete unnecessary data 4989 S: A223 NO COPY failed: disk is full 4991 7.1.3. BAD Response 4993 Contents: OPTIONAL response code 4994 human-readable text 4996 The BAD response indicates an error message from the server. When 4997 tagged, it reports a protocol-level error in the client's command; 4998 the tag indicates the command that caused the error. The untagged 4999 form indicates a protocol-level error for which the associated 5000 command can not be determined; it can also indicate an internal 5001 server failure. The human-readable text describes the condition. 5003 Example: C: ...very long command line... 5004 S: * BAD Command line too long 5005 C: ...empty line... 5006 S: * BAD Empty command line 5007 C: A443 EXPUNGE 5008 S: * BAD Disk crash, attempting salvage to a new disk! 5009 S: * OK Salvage successful, no data lost 5010 S: A443 OK Expunge completed 5012 7.1.4. PREAUTH Response 5014 Contents: OPTIONAL response code 5015 human-readable text 5017 The PREAUTH response is always untagged, and is one of three possible 5018 greetings at connection startup. It indicates that the connection 5019 has already been authenticated by external means; thus no LOGIN/ 5020 AUTHENTICATE command is needed. 5022 Example: S: * PREAUTH IMAP4rev2 server logged in as Smith 5024 7.1.5. BYE Response 5026 Contents: OPTIONAL response code 5027 human-readable text 5029 The BYE response is always untagged, and indicates that the server is 5030 about to close the connection. The human-readable text MAY be 5031 displayed to the user in a status report by the client. The BYE 5032 response is sent under one of four conditions: 5034 1. as part of a normal logout sequence. The server will close the 5035 connection after sending the tagged OK response to the LOGOUT 5036 command. 5038 2. as a panic shutdown announcement. The server closes the 5039 connection immediately. 5041 3. as an announcement of an inactivity autologout. The server 5042 closes the connection immediately. 5044 4. as one of three possible greetings at connection startup, 5045 indicating that the server is not willing to accept a connection 5046 from this client. The server closes the connection immediately. 5048 The difference between a BYE that occurs as part of a normal LOGOUT 5049 sequence (the first case) and a BYE that occurs because of a failure 5050 (the other three cases) is that the connection closes immediately in 5051 the failure case. In all cases the client SHOULD continue to read 5052 response data from the server until the connection is closed; this 5053 will ensure that any pending untagged or completion responses are 5054 read and processed. 5056 Example: S: * BYE Autologout; idle for too long 5058 7.2. Server Responses - Server and Mailbox Status 5060 These responses are always untagged. This is how server and mailbox 5061 status data are transmitted from the server to the client. Many of 5062 these responses typically result from a command with the same name. 5064 7.2.1. The ENABLED Response 5066 Contents: capability listing 5068 The ENABLED response occurs as a result of an ENABLE command. The 5069 capability listing contains a space-separated listing of capability 5070 names that the server supports and that were successfully enabled. 5071 The ENABLED response may contain no capabilities, which means that no 5072 extensions listed by the client were successfully enabled. 5074 7.2.2. CAPABILITY Response 5076 Contents: capability listing 5078 The CAPABILITY response occurs as a result of a CAPABILITY command. 5079 The capability listing contains a space-separated listing of 5080 capability names that the server supports. The capability listing 5081 MUST include the atom "IMAP4rev2". 5083 In addition, client and server implementations MUST implement the 5084 STARTTLS, LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) 5085 capabilities. See the Security Considerations section for important 5086 information. 5088 A capability name which begins with "AUTH=" indicates that the server 5089 supports that particular authentication mechanism. 5091 The LOGINDISABLED capability indicates that the LOGIN command is 5092 disabled, and that the server will respond with a tagged NO response 5093 to any attempt to use the LOGIN command even if the user name and 5094 password are valid. An IMAP client MUST NOT issue the LOGIN command 5095 if the server advertises the LOGINDISABLED capability. 5097 Other capability names indicate that the server supports an 5098 extension, revision, or amendment to the IMAP4rev2 protocol. Server 5099 responses MUST conform to this document until the client issues a 5100 command that uses the associated capability. 5102 Capability names MUST either begin with "X" or be informational, 5103 experimental or standards-track IMAP4rev2 extensions, revisions, or 5104 amendments registered with IANA. A server SHOULD NOT offer 5105 unregistered or non-standard capability names, unless such names are 5106 prefixed with an "X". 5108 Client implementations SHOULD NOT require any capability name other 5109 than "IMAP4rev2", and MUST ignore any unknown capability names. 5111 A server MAY send capabilities automatically, by using the CAPABILITY 5112 response code in the initial PREAUTH or OK responses, and by sending 5113 an updated CAPABILITY response code in the tagged OK response as part 5114 of a successful authentication. It is unnecessary for a client to 5115 send a separate CAPABILITY command if it recognizes these automatic 5116 capabilities. 5118 Example: S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI XPIG-LATIN 5120 7.2.3. LIST Response 5122 Contents: name attributes 5123 hierarchy delimiter 5124 name 5125 OPTIONAL extension data 5127 The LIST response occurs as a result of a LIST command. It returns a 5128 single name that matches the LIST specification. There can be 5129 multiple LIST responses for a single LIST command. 5131 The following base mailbox name attributes are defined: 5133 \NonExistent The "\NonExistent" attribute indicates that a mailbox 5134 name does not refer to an existing mailbox. Note that this 5135 attribute is not meaningful by itself, as mailbox names that match 5136 the canonical LIST pattern but don't exist must not be returned 5137 unless one of the two conditions listed below is also satisfied: 5139 1. The mailbox name also satisfies the selection criteria (for 5140 example, it is subscribed and the "SUBSCRIBED" selection 5141 option has been specified). 5143 2. "RECURSIVEMATCH" has been specified, and the mailbox name has 5144 at least one descendant mailbox name that does not match the 5145 LIST pattern and does match the selection criteria. 5147 In practice, this means that the "\NonExistent" attribute is 5148 usually returned with one or more of "\Subscribed", "\Remote", 5149 "\HasChildren", or the CHILDINFO extended data item. 5151 The "\NonExistent" attribute implies "\NoSelect". 5153 \Noinferiors It is not possible for any child levels of hierarchy to 5154 exist under this name; no child levels exist now and none can be 5155 created in the future. 5157 \Noselect It is not possible to use this name as a selectable 5158 mailbox. 5160 \HasChildren The presence of this attribute indicates that the 5161 mailbox has child mailboxes. A server SHOULD NOT set this 5162 attribute if there are child mailboxes and the user does not have 5163 permission to access any of them. In this case, \HasNoChildren 5164 SHOULD be used. In many cases, however, a server may not be able 5165 to efficiently compute whether a user has access to any child 5166 mailbox. Note that even though the \HasChildren attribute for a 5167 mailbox must be correct at the time of processing of the mailbox, 5168 a client must be prepared to deal with a situation when a mailbox 5169 is marked with the \HasChildren attribute, but no child mailbox 5170 appears in the response to the LIST command. This might happen, 5171 for example, due to children mailboxes being deleted or made 5172 inaccessible to the user (using access control) by another client 5173 before the server is able to list them. 5175 \HasNoChildren The presence of this attribute indicates that the 5176 mailbox has NO child mailboxes that are accessible to the 5177 currently authenticated user. 5179 \Marked The mailbox has been marked "interesting" by the server; the 5180 mailbox probably contains messages that have been added since the 5181 last time the mailbox was selected. 5183 \Unmarked The mailbox does not contain any additional messages since 5184 the last time the mailbox was selected. 5186 \Subscribed The mailbox name was subscribed to using the SUBSCRIBE 5187 command. 5189 \Remote The mailbox is a remote mailbox. 5191 It is an error for the server to return both a \HasChildren and a 5192 \HasNoChildren attribute in the same LIST response. A client that 5193 encounters a LIST response with both \HasChildren and \HasNoChildren 5194 attributes present should act as if both are absent in the LIST 5195 response. 5197 Note: the \HasNoChildren attribute should not be confused with the 5198 \NoInferiors attribute, which indicates that no child mailboxes 5199 exist now and none can be created in the future. 5201 If it is not feasible for the server to determine whether or not the 5202 mailbox is "interesting", the server SHOULD NOT send either \Marked 5203 or \Unmarked. The server MUST NOT send more than one of \Marked, 5204 \Unmarked, and \Noselect for a single mailbox, and MAY send none of 5205 these. 5207 In addition to the base mailbox name attributes defined above, an 5208 IMAP server MAY also include any or all of the following attributes 5209 that denote "role" (or "special-use") of a mailbox. These attributes 5210 are included along with base attributes defined above. A given 5211 mailbox may have none, one, or more than one of these attributes. In 5212 some cases, a special use is advice to a client about what to put in 5213 that mailbox. In other cases, it's advice to a client about what to 5214 expect to find there. 5216 \All This mailbox presents all messages in the user's message store. 5217 Implementations MAY omit some messages, such as, perhaps, those in 5218 \Trash and \Junk. When this special use is supported, it is 5219 almost certain to represent a virtual mailbox. 5221 \Archive This mailbox is used to archive messages. The meaning of 5222 an "archival" mailbox is server-dependent; typically, it will be 5223 used to get messages out of the inbox, or otherwise keep them out 5224 of the user's way, while still making them accessible. 5226 \Drafts This mailbox is used to hold draft messages -- typically, 5227 messages that are being composed but have not yet been sent. In 5228 some server implementations, this might be a virtual mailbox, 5229 containing messages from other mailboxes that are marked with the 5230 "\Draft" message flag. Alternatively, this might just be advice 5231 that a client put drafts here. 5233 \Flagged This mailbox presents all messages marked in some way as 5234 "important". When this special use is supported, it is likely to 5235 represent a virtual mailbox collecting messages (from other 5236 mailboxes) that are marked with the "\Flagged" message flag. 5238 \Junk This mailbox is where messages deemed to be junk mail are 5239 held. Some server implementations might put messages here 5240 automatically. Alternatively, this might just be advice to a 5241 client-side spam filter. 5243 \Sent This mailbox is used to hold copies of messages that have been 5244 sent. Some server implementations might put messages here 5245 automatically. Alternatively, this might just be advice that a 5246 client save sent messages here. 5248 \Trash This mailbox is used to hold messages that have been deleted 5249 or marked for deletion. In some server implementations, this 5250 might be a virtual mailbox, containing messages from other 5251 mailboxes that are marked with the "\Deleted" message flag. 5252 Alternatively, this might just be advice that a client that 5253 chooses not to use the IMAP "\Deleted" model should use this as 5254 its trash location. In server implementations that strictly 5255 expect the IMAP "\Deleted" model, this special use is likely not 5256 to be supported. 5258 All of special-use attributes are OPTIONAL, and any given server or 5259 message store may support any combination of the attributes, or none 5260 at all. In most cases, there will likely be at most one mailbox with 5261 a given attribute for a given user, but in some server or message 5262 store implementations it might be possible for multiple mailboxes to 5263 have the same special-use attribute. 5265 Special-use attributes are likely to be user-specific. User Adam 5266 might share his \Sent mailbox with user Barb, but that mailbox is 5267 unlikely to also serve as Barb's \Sent mailbox. 5269 Other mailbox name attributes can be found in the "IMAP Mailbox Name 5270 Attributes" registry [IMAP-MAILBOX-NAME-ATTRS-REG]. 5272 The hierarchy delimiter is a character used to delimit levels of 5273 hierarchy in a mailbox name. A client can use it to create child 5274 mailboxes, and to search higher or lower levels of naming hierarchy. 5275 All children of a top-level hierarchy node MUST use the same 5276 separator character. A NIL hierarchy delimiter means that no 5277 hierarchy exists; the name is a "flat" name. 5279 The name represents an unambiguous left-to-right hierarchy, and MUST 5280 be valid for use as a reference in LIST command. Unless \Noselect or 5281 \NonExistent is indicated, the name MUST also be valid as an argument 5282 for commands, such as SELECT, that accept mailbox names. 5284 The name might be followed by an OPTIONAL series of extended fields, 5285 a parenthesized list of tagged data (also referred to as "extended 5286 data item"). The first element of an extended field is a string, 5287 which identifies the type of data. [RFC5258] specified requirements 5288 on string registration (which are called "tags" there; such tags are 5289 not to be confused with IMAP command tags), in particular it said 5290 that "Tags MUST be registered with IANA". This document doesn't 5291 change that. See Section 9.5 of [RFC5258] for the registration 5292 template. The server MAY return data in the extended fields that was 5293 not directly solicited by the client in the corresponding LIST 5294 command. For example, the client can enable extra extended fields by 5295 using another IMAP extension that make use of the extended LIST 5296 responses. The client MUST ignore all extended fields it doesn't 5297 recognize. 5299 Example: S: * LIST (\Noselect) "/" ~/Mail/foo 5301 Example: S: * LIST (\Marked) ":" Tables (tablecloth (("edge" "lacy") 5302 ("color" "red")) Sample "text") 5303 S: * LIST () ":" Tables:new (tablecloth ("edge" "lacy") 5304 Sample ("text" "more text")) 5306 7.2.4. NAMESPACE Response 5308 Contents: the prefix and hierarchy delimiter to the server's 5309 Personal Namespace(s), Other Users' Namespace(s), and 5310 Shared Namespace(s) 5312 The NAMESPACE response occurs as a result of a NAMESPACE command. It 5313 contains the prefix and hierarchy delimiter to the server's Personal 5314 Namespace(s), Other Users' Namespace(s), and Shared Namespace(s) that 5315 the server wishes to expose. The response will contain a NIL for any 5316 namespace class that is not available. Namespace-Response-Extensions 5317 ABNF non terminal is defined for extensibility and MAY be included in 5318 the response. 5320 Example: S: * NAMESPACE (("" "/")) (("~" "/")) NIL 5322 7.2.5. STATUS Response 5324 Contents: name 5325 status parenthesized list 5327 The STATUS response occurs as a result of an STATUS command. It 5328 returns the mailbox name that matches the STATUS specification and 5329 the requested mailbox status information. 5331 Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 5333 7.2.6. ESEARCH Response 5335 Contents: one or more search-return-data pairs 5337 The ESEARCH response occurs as a result of a SEARCH or UID SEARCH 5338 command. 5340 The ESEARCH response starts with an optional search correlator. If 5341 it is missing, then the response was not caused by a particular IMAP 5342 command, whereas if it is present, it contains the tag of the command 5343 that caused the response to be returned. 5345 The search correlator is followed by an optional UID indicator. If 5346 this indicator is present, all data in the ESEARCH response refers to 5347 UIDs, otherwise all returned data refers to message numbers. 5349 The rest of the ESEARCH response contains one or more search data 5350 pairs. Each pair starts with unique return item name, followed by a 5351 space and the corresponding data. Search data pairs may be returned 5352 in any order. Unless specified otherwise by an extension, any return 5353 item name SHOULD appear only once in an ESEARCH response. 5355 [[TBD: describe the most common search data pairs returned.]] 5357 Example: S: * ESEARCH UID COUNT 5 ALL 4:19,21,28 5359 Example: S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28 5361 Example: S: * ESEARCH COUNT 5 ALL 1:17,21 5363 7.2.7. FLAGS Response 5365 Contents: flag parenthesized list 5367 The FLAGS response occurs as a result of a SELECT or EXAMINE command. 5368 The flag parenthesized list identifies the flags (at a minimum, the 5369 system-defined flags) that are applicable for this mailbox. Flags 5370 other than the system flags can also exist, depending on server 5371 implementation. 5373 The update from the FLAGS response MUST be recorded by the client. 5375 Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5377 7.3. Server Responses - Mailbox Size 5379 These responses are always untagged. This is how changes in the size 5380 of the mailbox are transmitted from the server to the client. 5381 Immediately following the "*" token is a number that represents a 5382 message count. 5384 7.3.1. EXISTS Response 5386 Contents: none 5388 The EXISTS response reports the number of messages in the mailbox. 5389 This response occurs as a result of a SELECT or EXAMINE command, and 5390 if the size of the mailbox changes (e.g., new messages). 5392 The update from the EXISTS response MUST be recorded by the client. 5394 Example: S: * 23 EXISTS 5396 7.4. Server Responses - Message Status 5398 These responses are always untagged. This is how message data are 5399 transmitted from the server to the client, often as a result of a 5400 command with the same name. Immediately following the "*" token is a 5401 number that represents a message sequence number. 5403 7.4.1. EXPUNGE Response 5405 Contents: none 5407 The EXPUNGE response reports that the specified message sequence 5408 number has been permanently removed from the mailbox. The message 5409 sequence number for each successive message in the mailbox is 5410 immediately decremented by 1, and this decrement is reflected in 5411 message sequence numbers in subsequent responses (including other 5412 untagged EXPUNGE responses). 5414 The EXPUNGE response also decrements the number of messages in the 5415 mailbox; it is not necessary to send an EXISTS response with the new 5416 value. 5418 As a result of the immediate decrement rule, message sequence numbers 5419 that appear in a set of successive EXPUNGE responses depend upon 5420 whether the messages are removed starting from lower numbers to 5421 higher numbers, or from higher numbers to lower numbers. For 5422 example, if the last 5 messages in a 9-message mailbox are expunged, 5423 a "lower to higher" server will send five untagged EXPUNGE responses 5424 for message sequence number 5, whereas a "higher to lower server" 5425 will send successive untagged EXPUNGE responses for message sequence 5426 numbers 9, 8, 7, 6, and 5. 5428 An EXPUNGE response MUST NOT be sent when no command is in progress, 5429 nor while responding to a FETCH, STORE, or SEARCH command. This rule 5430 is necessary to prevent a loss of synchronization of message sequence 5431 numbers between client and server. A command is not "in progress" 5432 until the complete command has been received; in particular, a 5433 command is not "in progress" during the negotiation of command 5434 continuation. 5436 Note: UID FETCH, UID STORE, and UID SEARCH are different commands 5437 from FETCH, STORE, and SEARCH. An EXPUNGE response MAY be sent 5438 during a UID command. 5440 The update from the EXPUNGE response MUST be recorded by the client. 5442 Example: S: * 44 EXPUNGE 5444 7.4.2. FETCH Response 5446 Contents: message data 5448 The FETCH response returns data about a message to the client. The 5449 data are pairs of data item names and their values in parentheses. 5450 This response occurs as the result of a FETCH or STORE command, as 5451 well as by unilateral server decision (e.g., flag updates). 5453 The current data items are: 5455 BINARY[]<> 5457 An or expressing the content of the 5458 specified section after removing any Content-Transfer-Encoding- 5459 related encoding. If is present it refers to the 5460 offset within the DECODED section data. 5462 If the domain of the decoded data is "8bit" and the data does 5463 not contain the NUL octet, the server SHOULD return the data in 5464 a instead of a ; this allows the client to 5465 determine if the "8bit" data contains the NUL octet without 5466 having to explicitly scan the data stream for for NULs. 5468 Messaging clients and servers have been notoriously lax in 5469 their adherence to the Internet CRLF convention for terminating 5470 lines of textual data (text/* media types) in Internet 5471 protocols. When sending data in BINARY[...] FETCH data item, 5472 servers MUST ensure that textual line-oriented sections are 5473 always transmitted using the IMAP4 CRLF line termination 5474 syntax, regardless of the underlying storage representation of 5475 the data on the server. 5477 If the server does not know how to decode the section's 5478 Content-Transfer-Encoding, it MUST fail the request and issue a 5479 "NO" response that contains the "UNKNOWN-CTE" response code. 5481 BINARY.SIZE[] 5483 The size of the section after removing any Content-Transfer- 5484 Encoding-related encoding. The value returned MUST match the 5485 size of the or that will be returned by 5486 the corresponding FETCH BINARY request. 5488 If the server does not know how to decode the section's 5489 Content-Transfer-Encoding, it MUST fail the request and issue a 5490 "NO" response that contains the "UNKNOWN-CTE" response code. 5492 BODY A form of BODYSTRUCTURE without extension data. 5494 BODY[
]<> 5496 A string expressing the body contents of the specified section. 5497 The string SHOULD be interpreted by the client according to the 5498 content transfer encoding, body type, and subtype. 5500 If the origin octet is specified, this string is a substring of 5501 the entire body contents, starting at that origin octet. This 5502 means that BODY[]<0> MAY be truncated, but BODY[] is NEVER 5503 truncated. 5505 Note: The origin octet facility MUST NOT be used by a server 5506 in a FETCH response unless the client specifically requested 5507 it by means of a FETCH of a BODY[
]<> data 5508 item. 5510 8-bit textual data is permitted if a [CHARSET] identifier is 5511 part of the body parameter parenthesized list for this section. 5512 Note that headers (part specifiers HEADER or MIME, or the 5513 header portion of a MESSAGE/RFC822 or MESSAGE/GLOBAL part), MAY 5514 be in UTF-8. Note also that the [RFC-5322] delimiting blank 5515 line between the header and the body is not affected by header 5516 line subsetting; the blank line is always included as part of 5517 header data, except in the case of a message which has no body 5518 and no blank line. 5520 Non-textual data such as binary data MUST be transfer encoded 5521 into a textual form, such as BASE64, prior to being sent to the 5522 client. To derive the original binary data, the client MUST 5523 decode the transfer encoded string. 5525 BODYSTRUCTURE 5527 A parenthesized list that describes the [MIME-IMB] body 5528 structure of a message. This is computed by the server by 5529 parsing the [MIME-IMB] header fields, defaulting various fields 5530 as necessary. 5532 For example, a simple text message of 48 lines and 2279 octets 5533 can have a body structure of: ("TEXT" "PLAIN" ("CHARSET" "US- 5534 ASCII") NIL NIL "7BIT" 2279 48) 5536 Multiple parts are indicated by parenthesis nesting. Instead 5537 of a body type as the first element of the parenthesized list, 5538 there is a sequence of one or more nested body structures. The 5539 second element of the parenthesized list is the multipart 5540 subtype (mixed, digest, parallel, alternative, etc.). 5542 For example, a two part message consisting of a text and a 5543 BASE64-encoded text attachment can have a body structure of: 5544 (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 5545 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") 5546 "<960723163407.20117h@cac.washington.edu>" "Compiler diff" 5547 "BASE64" 4554 73) "MIXED") 5549 Extension data follows the multipart subtype. Extension data 5550 is never returned with the BODY fetch, but can be returned with 5551 a BODYSTRUCTURE fetch. Extension data, if present, MUST be in 5552 the defined order. The extension data of a multipart body part 5553 are in the following order: 5555 body parameter parenthesized list A parenthesized list of 5556 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5557 "bar" is the value of "foo", and "rag" is the value of 5558 "baz"] as defined in [MIME-IMB]. Servers SHOULD decode 5559 parameter value continuations and parameter value character 5560 sets as described in [RFC2231], for example, if the message 5561 contains parameters "baz*0", "baz*1" and "baz*2", the server 5562 should RFC2231-decode them, concatenate and return the 5563 resulting value as a parameter "baz". Similarly, if the 5564 message contains parameters "foo*0*" and "foo*1*", the 5565 server should RFC2231-decode them, convert to UTF-8, 5566 concatenate and return the resulting value as a parameter 5567 "foo*". 5569 body disposition A parenthesized list, consisting of a 5570 disposition type string, followed by a parenthesized list of 5571 disposition attribute/value pairs as defined in 5572 [DISPOSITION]. Servers SHOULD decode parameter value 5573 continuations as described in [RFC2231]. 5575 body language A string or parenthesized list giving the body 5576 language value as defined in [LANGUAGE-TAGS]. 5578 body location A string giving the body content URI as defined 5579 in [LOCATION]. 5581 Any following extension data are not yet defined in this 5582 version of the protocol. Such extension data can consist of 5583 zero or more NILs, strings, numbers, or potentially nested 5584 parenthesized lists of such data. Client implementations that 5585 do a BODYSTRUCTURE fetch MUST be prepared to accept such 5586 extension data. Server implementations MUST NOT send such 5587 extension data until it has been defined by a revision of this 5588 protocol. 5590 The basic fields of a non-multipart body part are in the 5591 following order: 5593 body type A string giving the content media type name as 5594 defined in [MIME-IMB]. 5596 body subtype A string giving the content subtype name as 5597 defined in [MIME-IMB]. 5599 body parameter parenthesized list A parenthesized list of 5600 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5601 "bar" is the value of "foo" and "rag" is the value of "baz"] 5602 as defined in [MIME-IMB]. 5604 body id A string giving the Content-ID header field value as 5605 defined in Section 7 of [MIME-IMB]. 5607 body description A string giving the Content-Description 5608 header field value as defined in Section 8 of [MIME-IMB]. 5610 body encoding A string giving the content transfer encoding as 5611 defined in Section 6 of [MIME-IMB]. 5613 body size A number giving the size of the body in octets. 5614 Note that this size is the size in its transfer encoding and 5615 not the resulting size after any decoding. 5617 A body type of type MESSAGE and subtype RFC822 contains, 5618 immediately after the basic fields, the envelope structure, 5619 body structure, and size in text lines of the encapsulated 5620 message. 5622 A body type of type TEXT contains, immediately after the basic 5623 fields, the size of the body in text lines. Note that this 5624 size is the size in its content transfer encoding and not the 5625 resulting size after any decoding. 5627 Extension data follows the basic fields and the type-specific 5628 fields listed above. Extension data is never returned with the 5629 BODY fetch, but can be returned with a BODYSTRUCTURE fetch. 5630 Extension data, if present, MUST be in the defined order. 5632 The extension data of a non-multipart body part are in the 5633 following order: 5635 body MD5 A string giving the body MD5 value as defined in 5636 [MD5]. 5638 body disposition A parenthesized list with the same content 5639 and function as the body disposition for a multipart body 5640 part. 5642 body language A string or parenthesized list giving the body 5643 language value as defined in [LANGUAGE-TAGS]. 5645 body location A string giving the body content URI as defined 5646 in [LOCATION]. 5648 Any following extension data are not yet defined in this 5649 version of the protocol, and would be as described above under 5650 multipart extension data. 5652 ENVELOPE 5654 A parenthesized list that describes the envelope structure of a 5655 message. This is computed by the server by parsing the 5656 [RFC-5322] header into the component parts, defaulting various 5657 fields as necessary. 5659 The fields of the envelope structure are in the following 5660 order: date, subject, from, sender, reply-to, to, cc, bcc, in- 5661 reply-to, and message-id. The date, subject, in-reply-to, and 5662 message-id fields are strings. The from, sender, reply-to, to, 5663 cc, and bcc fields are parenthesized lists of address 5664 structures. 5666 An address structure is a parenthesized list that describes an 5667 electronic mail address. The fields of an address structure 5668 are in the following order: personal name, [SMTP] at-domain- 5669 list (source route, obs-route), mailbox name, and host name. 5671 [RFC-5322] group syntax is indicated by a special form of 5672 address structure in which the host name field is NIL. If the 5673 mailbox name field is also NIL, this is an end of group marker 5674 (semi-colon in RFC 822 syntax). If the mailbox name field is 5675 non-NIL, this is a start of group marker, and the mailbox name 5676 field holds the group name phrase. 5678 If the Date, Subject, In-Reply-To, and Message-ID header lines 5679 are absent in the [RFC-5322] header, the corresponding member 5680 of the envelope is NIL; if these header lines are present but 5681 empty the corresponding member of the envelope is the empty 5682 string. 5684 Note: some servers may return a NIL envelope member in the 5685 "present but empty" case. Clients SHOULD treat NIL and 5686 empty string as identical. 5688 Note: [RFC-5322] requires that all messages have a valid 5689 Date header. Therefore, for a well-formed message the date 5690 member in the envelope can not be NIL or the empty string. 5691 However it can be NIL for a malformed or a draft message. 5693 Note: [RFC-5322] requires that the In-Reply-To and Message- 5694 ID headers, if present, have non-empty content. Therefore, 5695 for a well-formed message the in-reply-to and message-id 5696 members in the envelope can not be the empty string. 5697 However they can still be the empty string for a malformed 5698 message. 5700 If the From, To, Cc, and Bcc header lines are absent in the 5701 [RFC-5322] header, or are present but empty, the corresponding 5702 member of the envelope is NIL. 5704 If the Sender or Reply-To lines are absent in the [RFC-5322] 5705 header, or are present but empty, the server sets the 5706 corresponding member of the envelope to be the same value as 5707 the from member (the client is not expected to know to do 5708 this). 5710 Note: [RFC-5322] requires that all messages have a valid 5711 From header. Therefore, for a well-formed message the from, 5712 sender, and reply-to members in the envelope can not be NIL. 5713 However they can be NIL for a malformed or a draft message. 5715 FLAGS A parenthesized list of flags that are set for this message. 5717 INTERNALDATE A string representing the internal date of the message. 5719 RFC822.SIZE A number expressing the [RFC-5322] size of the message. 5721 UID A number expressing the unique identifier of the message. 5723 If the server chooses to send unsolicited FETCH responses, they MUST 5724 include UID FETCH item. Note that this is a new requirement when 5725 compared to RFC 3501. 5727 Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827) 5729 7.5. Server Responses - Command Continuation Request 5731 The command continuation request response is indicated by a "+" token 5732 instead of a tag. This form of response indicates that the server is 5733 ready to accept the continuation of a command from the client. The 5734 remainder of this response is a line of text. 5736 This response is used in the AUTHENTICATE command to transmit server 5737 data to the client, and request additional client data. This 5738 response is also used if an argument to any command is a 5739 synchronizing literal. 5741 The client is not permitted to send the octets of the synchronizing 5742 literal unless the server indicates that it is expected. This 5743 permits the server to process commands and reject errors on a line- 5744 by-line basis. The remainder of the command, including the CRLF that 5745 terminates a command, follows the octets of the literal. If there 5746 are any additional command arguments, the literal octets are followed 5747 by a space and those arguments. 5749 Example: C: A001 LOGIN {11} 5750 S: + Ready for additional command text 5751 C: FRED FOOBAR {7} 5752 S: + Ready for additional command text 5753 C: fat man 5754 S: A001 OK LOGIN completed 5755 C: A044 BLURDYBLOOP {102856} 5756 S: A044 BAD No such command as "BLURDYBLOOP" 5758 8. Sample IMAP4rev2 connection 5760 The following is a transcript of an IMAP4rev2 connection. A long 5761 line in this sample is broken for editorial clarity. 5763 S: * OK IMAP4rev2 Service Ready 5764 C: a001 login mrc secret 5765 S: a001 OK LOGIN completed 5766 C: a002 select inbox 5767 S: * 18 EXISTS 5768 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5769 S: * OK [UIDVALIDITY 3857529045] UIDs valid 5770 S: * LIST () "/" INBOX ("OLDNAME" ("inbox")) 5771 S: a002 OK [READ-WRITE] SELECT completed 5772 C: a003 fetch 12 full 5773 S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700" 5774 RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)" 5775 "IMAP4rev2 WG mtg summary and minutes" 5776 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5777 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5778 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5779 ((NIL NIL "imap" "cac.washington.edu")) 5780 ((NIL NIL "minutes" "CNRI.Reston.VA.US") 5781 ("John Klensin" NIL "KLENSIN" "MIT.EDU")) NIL NIL 5782 "") 5783 BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 5784 92)) 5785 S: a003 OK FETCH completed 5786 C: a004 fetch 12 body[header] 5787 S: * 12 FETCH (BODY[HEADER] {342} 5788 S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT) 5789 S: From: Terry Gray 5790 S: Subject: IMAP4rev2 WG mtg summary and minutes 5791 S: To: imap@cac.washington.edu 5792 S: cc: minutes@CNRI.Reston.VA.US, John Klensin 5793 S: Message-Id: 5794 S: MIME-Version: 1.0 5795 S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 5796 S: 5797 S: ) 5798 S: a004 OK FETCH completed 5799 C: a005 store 12 +flags \deleted 5800 S: * 12 FETCH (FLAGS (\Seen \Deleted)) 5801 S: a005 OK +FLAGS completed 5802 C: a006 logout 5803 S: * BYE IMAP4rev2 server terminating connection 5804 S: a006 OK LOGOUT completed 5806 9. Formal Syntax 5808 The following syntax specification uses the Augmented Backus-Naur 5809 Form (ABNF) notation as specified in [ABNF]. 5811 In the case of alternative or optional rules in which a later rule 5812 overlaps an earlier rule, the rule which is listed earlier MUST take 5813 priority. For example, "\Seen" when parsed as a flag is the \Seen 5814 flag name and not a flag-extension, even though "\Seen" can be parsed 5815 as a flag-extension. Some, but not all, instances of this rule are 5816 noted below. 5818 Note: [ABNF] rules MUST be followed strictly; in particular: 5820 (1) Except as noted otherwise, all alphabetic characters are case- 5821 insensitive. The use of upper or lower case characters to define 5822 token strings is for editorial clarity only. Implementations MUST 5823 accept these strings in a case-insensitive fashion. 5825 (2) In all cases, SP refers to exactly one space. It is NOT 5826 permitted to substitute TAB, insert additional spaces, or 5827 otherwise treat SP as being equivalent to LWSP. 5829 (3) The ASCII NUL character, %x00, MUST NOT be used at any time. 5831 address = "(" addr-name SP addr-adl SP addr-mailbox SP 5832 addr-host ")" 5834 addr-adl = nstring 5835 ; Holds route from [RFC-5322] obs-route if 5836 ; non-NIL 5838 addr-host = nstring 5839 ; NIL indicates [RFC-5322] group syntax. 5840 ; Otherwise, holds [RFC-5322] domain name 5842 addr-mailbox = nstring 5843 ; NIL indicates end of [RFC-5322] group; if 5844 ; non-NIL and addr-host is NIL, holds 5845 ; [RFC-5322] group name. 5846 ; Otherwise, holds [RFC-5322] local-part 5847 ; after removing [RFC-5322] quoting 5849 addr-name = nstring 5850 ; If non-NIL, holds phrase from [RFC-5322] 5851 ; mailbox after removing [RFC-5322] quoting 5853 append = "APPEND" SP mailbox [SP flag-list] [SP date-time] SP 5854 literal 5856 append-uid = uniqueid 5858 astring = 1*ASTRING-CHAR / string 5859 ASTRING-CHAR = ATOM-CHAR / resp-specials 5861 atom = 1*ATOM-CHAR 5863 ATOM-CHAR = 5865 atom-specials = "(" / ")" / "{" / SP / CTL / list-wildcards / 5866 quoted-specials / resp-specials 5868 authenticate = "AUTHENTICATE" SP auth-type [SP initial-resp] 5869 *(CRLF base64) 5871 auth-type = atom 5872 ; Defined by [SASL] 5874 base64 = *(4base64-char) [base64-terminal] 5876 base64-char = ALPHA / DIGIT / "+" / "/" 5877 ; Case-sensitive 5879 base64-terminal = (2base64-char "==") / (3base64-char "=") 5881 body = "(" (body-type-1part / body-type-mpart) ")" 5883 body-extension = nstring / number / 5884 "(" body-extension *(SP body-extension) ")" 5885 ; Future expansion. Client implementations 5886 ; MUST accept body-extension fields. Server 5887 ; implementations MUST NOT generate 5888 ; body-extension fields except as defined by 5889 ; future standard or standards-track 5890 ; revisions of this specification. 5892 body-ext-1part = body-fld-md5 [SP body-fld-dsp [SP body-fld-lang 5893 [SP body-fld-loc *(SP body-extension)]]] 5894 ; MUST NOT be returned on non-extensible 5895 ; "BODY" fetch 5897 body-ext-mpart = body-fld-param [SP body-fld-dsp [SP body-fld-lang 5898 [SP body-fld-loc *(SP body-extension)]]] 5899 ; MUST NOT be returned on non-extensible 5900 ; "BODY" fetch 5902 body-fields = body-fld-param SP body-fld-id SP body-fld-desc SP 5903 body-fld-enc SP body-fld-octets 5905 body-fld-desc = nstring 5906 body-fld-dsp = "(" string SP body-fld-param ")" / nil 5908 body-fld-enc = (DQUOTE ("7BIT" / "8BIT" / "BINARY" / "BASE64"/ 5909 "QUOTED-PRINTABLE") DQUOTE) / string 5910 ; Content-Transfer-Encoding header field value. 5911 ; Defaults to "7BIT" (as per RFC 2045) 5912 ; if not present in the body part. 5914 body-fld-id = nstring 5916 body-fld-lang = nstring / "(" string *(SP string) ")" 5918 body-fld-loc = nstring 5920 body-fld-lines = number 5922 body-fld-md5 = nstring 5924 body-fld-octets = number 5926 body-fld-param = "(" string SP string *(SP string SP string) ")" / nil 5928 body-type-1part = (body-type-basic / body-type-msg / body-type-text) 5929 [SP body-ext-1part] 5931 body-type-basic = media-basic SP body-fields 5932 ; MESSAGE subtype MUST NOT be "RFC822" or "GLOBAL" 5934 body-type-mpart = 1*body SP media-subtype 5935 [SP body-ext-mpart] 5936 ; MULTIPART body part 5938 body-type-msg = media-message SP body-fields SP envelope 5939 SP body SP body-fld-lines 5941 body-type-text = media-text SP body-fields SP body-fld-lines 5943 capability = ("AUTH=" auth-type) / atom 5944 ; New capabilities MUST begin with "X" or be 5945 ; registered with IANA in 5946 ; a standards-track, an experimental 5947 ; or an informational RFC. 5949 capability-data = "CAPABILITY" *(SP capability) SP "IMAP4rev2" 5950 *(SP capability) 5951 ; Servers MUST implement the STARTTLS, AUTH=PLAIN, 5952 ; and LOGINDISABLED capabilities. 5953 ; Servers which offer RFC 1730 compatibility MUST 5954 ; list "IMAP4" as the first capability. 5955 ; Servers which offer RFC 3501 compatibility MUST 5956 ; list "IMAP4rev1" as one of capabilities. 5958 CHAR = 5960 CHAR8 = %x01-ff 5961 ; any OCTET except NUL, %x00 5963 charset = atom / quoted 5965 childinfo-extended-item = "CHILDINFO" SP "(" 5966 list-select-base-opt-quoted 5967 *(SP list-select-base-opt-quoted) ")" 5968 ; Extended data item (mbox-list-extended-item) 5969 ; returned when the RECURSIVEMATCH 5970 ; selection option is specified. 5971 ; Note 1: the CHILDINFO extended data item tag can be 5972 ; returned with and without surrounding quotes, as per 5973 ; mbox-list-extended-item-tag production. 5974 ; Note 2: The selection options are always returned 5975 ; quoted, unlike their specification in 5976 ; the extended LIST command. 5978 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 5979 ; attributes for CHILDREN return option, at most one 5980 ; possible per LIST response 5982 command = tag SP (command-any / command-auth / command-nonauth / 5983 command-select) CRLF 5984 ; Modal based on state 5986 command-any = "CAPABILITY" / "LOGOUT" / "NOOP" / enable / x-command 5987 ; Valid in all states 5989 command-auth = append / create / delete / examine / list / 5990 Namespace-Command / 5991 rename / select / status / subscribe / unsubscribe / 5992 idle 5993 ; Valid only in Authenticated or Selected state 5995 command-nonauth = login / authenticate / "STARTTLS" 5996 ; Valid only when in Not Authenticated state 5998 command-select = "CLOSE" / "UNSELECT" / "EXPUNGE" / copy / 5999 move / fetch / store / search / uid 6000 ; Valid only when in Selected state 6002 continue-req = "+" SP (resp-text / base64) CRLF 6004 copy = "COPY" SP sequence-set SP mailbox 6006 create = "CREATE" SP mailbox 6007 ; Use of INBOX gives a NO error 6009 date = date-text / DQUOTE date-text DQUOTE 6011 date-day = 1*2DIGIT 6012 ; Day of month 6014 date-day-fixed = (SP DIGIT) / 2DIGIT 6015 ; Fixed-format version of date-day 6017 date-month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / 6018 "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" 6020 date-text = date-day "-" date-month "-" date-year 6022 date-year = 4DIGIT 6024 date-time = DQUOTE date-day-fixed "-" date-month "-" date-year 6025 SP time SP zone DQUOTE 6027 delete = "DELETE" SP mailbox 6028 ; Use of INBOX gives a NO error 6030 digit-nz = %x31-39 6031 ; 1-9 6033 eitem-standard-tag = atom 6034 ; a tag for LIST extended data item defined in a Standard 6035 ; Track or Experimental RFC. 6037 eitem-vendor-tag = vendor-token "-" atom 6038 ; a vendor-specific tag for LIST extended data item 6040 enable = "ENABLE" 1*(SP capability) 6042 enable-data = "ENABLED" *(SP capability) 6044 envelope = "(" env-date SP env-subject SP env-from SP 6045 env-sender SP env-reply-to SP env-to SP env-cc SP 6046 env-bcc SP env-in-reply-to SP env-message-id ")" 6048 env-bcc = "(" 1*address ")" / nil 6049 env-cc = "(" 1*address ")" / nil 6051 env-date = nstring 6053 env-from = "(" 1*address ")" / nil 6055 env-in-reply-to = nstring 6057 env-message-id = nstring 6059 env-reply-to = "(" 1*address ")" / nil 6061 env-sender = "(" 1*address ")" / nil 6063 env-subject = nstring 6065 env-to = "(" 1*address ")" / nil 6067 esearch-response = "ESEARCH" [search-correlator] [SP "UID"] 6068 *(SP search-return-data) 6069 ; ESEARCH response replaces SEARCH response 6070 ; from IMAP4rev1. 6072 examine = "EXAMINE" SP mailbox 6074 fetch = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" / 6075 fetch-att / "(" fetch-att *(SP fetch-att) ")") 6077 fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" / 6078 "RFC822.SIZE" / 6079 "BODY" ["STRUCTURE"] / "UID" / 6080 "BODY" section [partial] / 6081 "BODY.PEEK" section [partial] / 6082 "BINARY" [".PEEK"] section-binary [partial] / 6083 "BINARY.SIZE" section-binary 6085 flag = "\Answered" / "\Flagged" / "\Deleted" / 6086 "\Seen" / "\Draft" / flag-keyword / flag-extension 6087 ; Does not include "\Recent" 6089 flag-extension = "\" atom 6090 ; Future expansion. Client implementations 6091 ; MUST accept flag-extension flags. Server 6092 ; implementations MUST NOT generate 6093 ; flag-extension flags except as defined by 6094 ; future standard or standards-track 6095 ; revisions of this specification. 6096 ; "\Recent" was defined in RFC 3501 6097 ; and is now deprecated. 6099 flag-fetch = flag 6101 flag-keyword = "$MDNSent" / "$Forwarded" / "$Junk" / 6102 "$NotJunk" / "$Phishing" / atom 6104 flag-list = "(" [flag *(SP flag)] ")" 6106 flag-perm = flag / "\*" 6108 greeting = "*" SP (resp-cond-auth / resp-cond-bye) CRLF 6110 header-fld-name = astring 6112 header-list = "(" header-fld-name *(SP header-fld-name) ")" 6114 idle = "IDLE" CRLF "DONE" 6116 initial-resp = (base64 / "=") 6117 ; "initial response" defined in 6118 ; Section 5.1 of [RFC4422] 6120 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 6121 [SP list-return-opts] 6123 list-mailbox = 1*list-char / string 6125 list-char = ATOM-CHAR / list-wildcards / resp-specials 6127 list-return-opts = "RETURN" SP 6128 "(" [return-option *(SP return-option)] ")" 6129 ; list return options, e.g., CHILDREN 6131 list-select-base-opt = "SUBSCRIBED" / option-extension 6132 ; options that can be used by themselves 6134 list-select-base-opt-quoted = DQUOTE list-select-base-opt DQUOTE 6136 list-select-independent-opt = "REMOTE" / option-extension 6137 ; options that do not syntactically interact with 6138 ; other options 6140 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 6141 ; options that require a list-select-base-opt 6142 ; to also be present 6144 list-select-opt = list-select-base-opt / list-select-independent-opt 6145 / list-select-mod-opt 6146 ; An option registration template is described in 6147 ; Section 9.3 of this document. 6149 list-select-opts = "(" [ 6150 (*(list-select-opt SP) list-select-base-opt 6151 *(SP list-select-opt)) 6152 / (list-select-independent-opt 6153 *(SP list-select-independent-opt)) 6154 ] ")" 6155 ; Any number of options may be in any order. 6156 ; If a list-select-mod-opt appears, then a 6157 ; list-select-base-opt must also appear. 6158 ; This allows these: 6159 ; () 6160 ; (REMOTE) 6161 ; (SUBSCRIBED) 6162 ; (SUBSCRIBED REMOTE) 6163 ; (SUBSCRIBED RECURSIVEMATCH) 6164 ; (SUBSCRIBED REMOTE RECURSIVEMATCH) 6165 ; But does NOT allow these: 6166 ; (RECURSIVEMATCH) 6167 ; (REMOTE RECURSIVEMATCH) 6169 list-wildcards = "%" / "*" 6171 literal = "{" number ["+"] "}" CRLF *CHAR8 6172 ; represents the number of CHAR8s. 6173 ; A non-synchronizing literal is distinguished from 6174 ; a synchronizing literal by presence of the "+" 6175 ; before the closing "}". 6176 ; Non synchronizing literals are not allowed when 6177 ; sent from server to the client. 6179 literal8 = "~{" number "}" CRLF *OCTET 6180 ; represents the number of OCTETs 6181 ; in the response string. 6183 login = "LOGIN" SP userid SP password 6185 mailbox = "INBOX" / astring 6186 ; INBOX is case-insensitive. All case variants of 6187 ; INBOX (e.g., "iNbOx") MUST be interpreted as INBOX 6188 ; not as an astring. An astring which consists of 6189 ; the case-insensitive sequence "I" "N" "B" "O" "X" 6190 ; is considered to be INBOX and not an astring. 6191 ; Refer to section 5.1 for further 6192 ; semantic details of mailbox names. 6194 mailbox-data = "FLAGS" SP flag-list / "LIST" SP mailbox-list / 6195 esearch-response / 6196 "STATUS" SP mailbox SP "(" [status-att-list] ")" / 6197 number SP "EXISTS" / Namespace-Response 6199 mailbox-list = "(" [mbx-list-flags] ")" SP 6200 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 6201 [SP mbox-list-extended] 6202 ; This is the list information pointed to by the ABNF 6203 ; item "mailbox-data", which is defined in [IMAP4] 6205 mbox-list-extended = "(" [mbox-list-extended-item 6206 *(SP mbox-list-extended-item)] ")" 6208 mbox-list-extended-item = mbox-list-extended-item-tag SP 6209 tagged-ext-val 6211 mbox-list-extended-item-tag = astring 6212 ; The content MUST conform to either "eitem-vendor-tag" 6213 ; or "eitem-standard-tag" ABNF productions. 6215 mbox-or-pat = list-mailbox / patterns 6217 mbx-list-flags = *(mbx-list-oflag SP) mbx-list-sflag 6218 *(SP mbx-list-oflag) / 6219 mbx-list-oflag *(SP mbx-list-oflag) 6221 mbx-list-oflag = "\Noinferiors" / child-mbox-flag / 6222 "\Subscribed" / "\Remote" / flag-extension 6223 ; Other flags; multiple possible per LIST response 6225 mbx-list-sflag = "\NonExistent" / "\Noselect" / "\Marked" / "\Unmarked" 6226 ; Selectability flags; only one per LIST response 6228 media-basic = ((DQUOTE ("APPLICATION" / "AUDIO" / "IMAGE" / 6229 "FONT" / "MESSAGE" / "MODEL" / "VIDEO" ) DQUOTE) 6230 / string) 6231 SP media-subtype 6232 ; Defined in [MIME-IMT]. 6233 ; FONT defined in RFC 8081. 6235 media-message = DQUOTE "MESSAGE" DQUOTE SP 6236 DQUOTE ("RFC822" / "GLOBAL") DQUOTE 6237 ; Defined in [MIME-IMT] 6239 media-subtype = string 6240 ; Defined in [MIME-IMT] 6242 media-text = DQUOTE "TEXT" DQUOTE SP media-subtype 6243 ; Defined in [MIME-IMT] 6245 message-data = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att)) 6247 move = "MOVE" SP sequence-set SP mailbox 6249 msg-att = "(" (msg-att-dynamic / msg-att-static) 6250 *(SP (msg-att-dynamic / msg-att-static)) ")" 6252 msg-att-dynamic = "FLAGS" SP "(" [flag-fetch *(SP flag-fetch)] ")" 6253 ; MAY change for a message 6255 msg-att-static = "ENVELOPE" SP envelope / "INTERNALDATE" SP date-time / 6256 "RFC822.SIZE" SP number / 6257 "BODY" ["STRUCTURE"] SP body / 6258 "BODY" section ["<" number ">"] SP nstring / 6259 "BINARY" section-binary SP (nstring / literal8) / 6260 "BINARY.SIZE" section-binary SP number / 6261 "UID" SP uniqueid 6262 ; MUST NOT change for a message 6264 name-component = 1*UTF8-CHAR 6265 ; MUST NOT contain ".", "/", "%", or "*" 6267 Namespace = nil / "(" 1*Namespace-Descr ")" 6269 Namespace-Command = "NAMESPACE" 6271 Namespace-Descr = "(" string SP 6272 (DQUOTE QUOTED-CHAR DQUOTE / nil) 6273 [Namespace-Response-Extensions] ")" 6275 Namespace-Response-Extensions = *Namespace-Response-Extension 6277 Namespace-Response-Extension = SP string SP 6278 "(" string *(SP string) ")" 6280 Namespace-Response = "NAMESPACE" SP Namespace 6281 SP Namespace SP Namespace 6282 ; The first Namespace is the Personal Namespace(s). 6283 ; The second Namespace is the Other Users' 6284 ; Namespace(s). 6285 ; The third Namespace is the Shared Namespace(s). 6287 nil = "NIL" 6288 nstring = string / nil 6290 number = 1*DIGIT 6291 ; Unsigned 32-bit integer 6292 ; (0 <= n < 4,294,967,296) 6294 number64 = 1*DIGIT 6295 ; Unsigned 63-bit integer 6296 ; (0 <= n <= 9,223,372,036,854,775,807) 6298 nz-number = digit-nz *DIGIT 6299 ; Non-zero unsigned 32-bit integer 6300 ; (0 < n < 4,294,967,296) 6302 oldname-extended-item = "OLDNAME" SP "(" mailbox ")" 6303 ; Extended data item (mbox-list-extended-item) 6304 ; returned in a LIST response when a mailbox is 6305 ; renamed or deleted. Also returned when 6306 ; the server canonicalized the provided mailbox 6307 ; name. 6308 ; Note 1: the OLDNAME tag can be returned 6309 ; with or without surrounding quotes, as per 6310 ; mbox-list-extended-item-tag production. 6312 option-extension = (option-standard-tag / option-vendor-tag) 6313 [SP option-value] 6315 option-standard-tag = atom 6316 ; an option defined in a Standards Track or 6317 ; Experimental RFC 6319 option-val-comp = astring / 6320 option-val-comp *(SP option-val-comp) / 6321 "(" option-val-comp ")" 6323 option-value = "(" option-val-comp ")" 6325 option-vendor-tag = vendor-token "-" atom 6326 ; a vendor-specific option, non-standard 6328 partial-range = number ["." nz-number] 6329 ; Copied from RFC 5092 (IMAP URL) 6331 partial = "<" number "." nz-number ">" 6332 ; Partial FETCH request. 0-based offset of 6333 ; the first octet, followed by the number of octets 6334 ; in the fragment. 6336 password = astring 6338 patterns = "(" list-mailbox ")" 6339 ; [RFC5258] supports multiple patterns, 6340 ; but this document only requires one 6341 ; to be supported. 6342 ; If the server is also implementing 6343 ; [RFC5258], "patterns" syntax from that 6344 ; document must be followed. 6346 quoted = DQUOTE *QUOTED-CHAR DQUOTE 6348 QUOTED-CHAR = / 6349 "\" quoted-specials / UTF8-2 / UTF8-3 / UTF8-4 6351 quoted-specials = DQUOTE / "\" 6353 rename = "RENAME" SP mailbox SP mailbox 6354 ; Use of INBOX as a destination gives a NO error 6356 response = *(continue-req / response-data) response-done 6358 response-data = "*" SP (resp-cond-state / resp-cond-bye / 6359 mailbox-data / message-data / capability-data / 6360 enable-data) CRLF 6362 response-done = response-tagged / response-fatal 6364 response-fatal = "*" SP resp-cond-bye CRLF 6365 ; Server closes connection immediately 6367 response-tagged = tag SP resp-cond-state CRLF 6369 resp-code-apnd = "APPENDUID" SP nz-number SP append-uid 6371 resp-code-copy = "COPYUID" SP nz-number SP uid-set SP uid-set 6373 resp-cond-auth = ("OK" / "PREAUTH") SP resp-text 6374 ; Authentication condition 6376 resp-cond-bye = "BYE" SP resp-text 6378 resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text 6379 ; Status condition 6381 resp-specials = "]" 6383 resp-text = ["[" resp-text-code "]" SP] [text] 6384 resp-text-code = "ALERT" / 6385 "BADCHARSET" [SP "(" charset *(SP charset) ")" ] / 6386 capability-data / "PARSE" / 6387 "PERMANENTFLAGS" SP 6388 "(" [flag-perm *(SP flag-perm)] ")" / 6389 "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / 6390 "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number / 6391 resp-code-apnd / resp-code-copy / "UIDNOTSTICKY" / 6392 "UNAVAILABLE" / "AUTHENTICATIONFAILED" / 6393 "AUTHORIZATIONFAILED" / "EXPIRED" / 6394 "PRIVACYREQUIRED" / "CONTACTADMIN" / "NOPERM" / 6395 "INUSE" / "EXPUNGEISSUED" / "CORRUPTION" / 6396 "SERVERBUG" / "CLIENTBUG" / "CANNOT" / 6397 "LIMIT" / "OVERQUOTA" / "ALREADYEXISTS" / 6398 "NONEXISTENT" / "NOTSAVED" / "HASCHILDREN" / 6399 "CLOSED" / 6400 "UNKNOWN-CTE" / 6401 atom [SP 1*] 6403 return-option = "SUBSCRIBED" / "CHILDREN" / status-option / 6404 option-extension 6406 search = "SEARCH" [search-return-opts] 6407 SP search-program 6409 search-correlator = SP "(" "TAG" SP tag-string ")" 6411 search-key = "ALL" / "ANSWERED" / "BCC" SP astring / 6412 "BEFORE" SP date / "BODY" SP astring / 6413 "CC" SP astring / "DELETED" / "FLAGGED" / 6414 "FROM" SP astring / "KEYWORD" SP flag-keyword / 6415 "ON" SP date / "SEEN" / 6416 "SINCE" SP date / "SUBJECT" SP astring / 6417 "TEXT" SP astring / "TO" SP astring / 6418 "UNANSWERED" / "UNDELETED" / "UNFLAGGED" / 6419 "UNKEYWORD" SP flag-keyword / "UNSEEN" / 6420 ; Above this line were in [IMAP2] 6421 "DRAFT" / "HEADER" SP header-fld-name SP astring / 6422 "LARGER" SP number / "NOT" SP search-key / 6423 "OR" SP search-key SP search-key / 6424 "SENTBEFORE" SP date / "SENTON" SP date / 6425 "SENTSINCE" SP date / "SMALLER" SP number / 6426 "UID" SP sequence-set / "UNDRAFT" / sequence-set / 6427 "(" search-key *(SP search-key) ")" 6429 search-modifier-name = tagged-ext-label 6431 search-mod-params = tagged-ext-val 6432 ; This non-terminal shows recommended syntax 6433 ; for future extensions. 6435 search-program = ["CHARSET" SP charset SP] 6436 search-key *(SP search-key) 6437 ; CHARSET argument to SEARCH MUST be 6438 ; registered with IANA. 6440 search-ret-data-ext = search-modifier-name SP search-return-value 6441 ; Note that not every SEARCH return option 6442 ; is required to have the corresponding 6443 ; ESEARCH return data. 6445 search-return-data = "MIN" SP nz-number / 6446 "MAX" SP nz-number / 6447 "ALL" SP sequence-set / 6448 "COUNT" SP number / 6449 search-ret-data-ext 6450 ; All return data items conform to 6451 ; search-ret-data-ext syntax. 6452 ; Note that "$" marker is not allowed 6453 ; after the ALL return data item. 6455 search-return-opts = SP "RETURN" SP "(" [search-return-opt 6456 *(SP search-return-opt)] ")" 6458 search-return-opt = "MIN" / "MAX" / "ALL" / "COUNT" / 6459 "SAVE" / 6460 search-ret-opt-ext 6461 ; conforms to generic search-ret-opt-ext 6462 ; syntax 6464 search-ret-opt-ext = search-modifier-name [SP search-mod-params] 6466 search-return-value = tagged-ext-val 6467 ; Data for the returned search option. 6468 ; A single "nz-number"/"number"/"number64" value 6469 ; can be returned as an atom (i.e., without 6470 ; quoting). A sequence-set can be returned 6471 ; as an atom as well. 6473 section = "[" [section-spec] "]" 6475 section-binary = "[" [section-part] "]" 6477 section-msgtext = "HEADER" / "HEADER.FIELDS" [".NOT"] SP header-list / 6478 "TEXT" 6479 ; top-level or MESSAGE/RFC822 or MESSAGE/GLOBAL part 6481 section-part = nz-number *("." nz-number) 6482 ; body part reference. 6483 ; Allows for accessing nested body parts. 6485 section-spec = section-msgtext / (section-part ["." section-text]) 6487 section-text = section-msgtext / "MIME" 6488 ; text other than actual body part (headers, etc.) 6490 select = "SELECT" SP mailbox 6492 seq-number = nz-number / "*" 6493 ; message sequence number (COPY, FETCH, STORE 6494 ; commands) or unique identifier (UID COPY, 6495 ; UID FETCH, UID STORE commands). 6496 ; * represents the largest number in use. In 6497 ; the case of message sequence numbers, it is 6498 ; the number of messages in a non-empty mailbox. 6499 ; In the case of unique identifiers, it is the 6500 ; unique identifier of the last message in the 6501 ; mailbox or, if the mailbox is empty, the 6502 ; mailbox's current UIDNEXT value. 6503 ; The server should respond with a tagged BAD 6504 ; response to a command that uses a message 6505 ; sequence number greater than the number of 6506 ; messages in the selected mailbox. This 6507 ; includes "*" if the selected mailbox is empty. 6509 seq-range = seq-number ":" seq-number 6510 ; two seq-number values and all values between 6511 ; these two regardless of order. 6512 ; Example: 2:4 and 4:2 are equivalent and indicate 6513 ; values 2, 3, and 4. 6514 ; Example: a unique identifier sequence range of 6515 ; 3291:* includes the UID of the last message in 6516 ; the mailbox, even if that value is less than 3291. 6518 sequence-set = (seq-number / seq-range) ["," sequence-set] 6519 ; set of seq-number values, regardless of order. 6520 ; Servers MAY coalesce overlaps and/or execute the 6521 ; sequence in any order. 6522 ; Example: a message sequence number set of 6523 ; 2,4:7,9,12:* for a mailbox with 15 messages is 6524 ; equivalent to 2,4,5,6,7,9,12,13,14,15 6525 ; Example: a message sequence number set of *:4,5:7 6526 ; for a mailbox with 10 messages is equivalent to 6527 ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and 6528 ; overlap coalesced to be 4,5,6,7,8,9,10. 6530 sequence-set =/ seq-last-command 6531 ; Allow for "result of the last command" indicator. 6533 seq-last-command = "$" 6535 status = "STATUS" SP mailbox SP 6536 "(" status-att *(SP status-att) ")" 6538 status-att = "MESSAGES" / "UIDNEXT" / "UIDVALIDITY" / 6539 "UNSEEN" / "DELETED" / "SIZE" 6541 status-att-val = ("MESSAGES" SP number) / 6542 ("UIDNEXT" SP nz-number) / 6543 ("UIDVALIDITY" SP nz-number) / 6544 ("UNSEEN" SP number) / 6545 ("DELETED" SP number) / 6546 ("SIZE" SP number64) 6547 ; Extensions to the STATUS responses 6548 ; should extend this production. 6549 ; Extensions should use the generic 6550 ; syntax defined by tagged-ext. 6552 status-att-list = status-att-val *(SP status-att-val) 6554 status-option = "STATUS" SP "(" status-att *(SP status-att) ")" 6555 ; This ABNF production complies with 6556 ; syntax. 6558 store = "STORE" SP sequence-set SP store-att-flags 6560 store-att-flags = (["+" / "-"] "FLAGS" [".SILENT"]) SP 6561 (flag-list / (flag *(SP flag))) 6563 string = quoted / literal 6565 subscribe = "SUBSCRIBE" SP mailbox 6567 tag = 1* 6569 tag-string = astring 6570 ; represented as 6572 tagged-ext-label = tagged-label-fchar *tagged-label-char 6573 ; Is a valid RFC 3501 "atom". 6575 tagged-label-fchar = ALPHA / "-" / "_" / "." 6577 tagged-label-char = tagged-label-fchar / DIGIT / ":" 6578 tagged-ext-comp = astring / 6579 tagged-ext-comp *(SP tagged-ext-comp) / 6580 "(" tagged-ext-comp ")" 6581 ; Extensions that follow this general 6582 ; syntax should use nstring instead of 6583 ; astring when appropriate in the context 6584 ; of the extension. 6585 ; Note that a message set or a "number" 6586 ; can always be represented as an "atom". 6587 ; An URL should be represented as 6588 ; a "quoted" string. 6590 tagged-ext-simple = sequence-set / number / number64 6592 tagged-ext-val = tagged-ext-simple / 6593 "(" [tagged-ext-comp] ")" 6595 text = 1*(TEXT-CHAR / UTF8-2 / UTF8-3 / UTF8-4) 6596 ; Non ASCII text can only be returned 6597 ; after ENABLE IMAP4rev2 command 6599 TEXT-CHAR = 6601 time = 2DIGIT ":" 2DIGIT ":" 2DIGIT 6602 ; Hours minutes seconds 6604 uid = "UID" SP 6605 (copy / move / fetch / search / store / uid-expunge) 6606 ; Unique identifiers used instead of message 6607 ; sequence numbers 6609 uid-expunge = "EXPUNGE" SP sequence-set 6610 ; Unique identifiers used instead of message 6611 ; sequence numbers 6613 uid-set = (uniqueid / uid-range) *("," uid-set) 6615 uid-range = (uniqueid ":" uniqueid) 6616 ; two uniqueid values and all values 6617 ; between these two regards of order. 6618 ; Example: 2:4 and 4:2 are equivalent. 6620 uniqueid = nz-number 6621 ; Strictly ascending 6623 unsubscribe = "UNSUBSCRIBE" SP mailbox 6625 userid = astring 6626 UTF8-2 = 6628 UTF8-3 = 6630 UTF8-4 = 6632 vendor-token = "vendor." name-component 6633 ; Definition copied from RFC 2244. 6634 ; MUST be registered with IANA 6636 x-command = "X" atom 6638 zone = ("+" / "-") 4DIGIT 6639 ; Signed four-digit value of hhmm representing 6640 ; hours and minutes east of Greenwich (that is, 6641 ; the amount that the given time differs from 6642 ; Universal Time). Subtracting the timezone 6643 ; from the given time will give the UT form. 6644 ; The Universal Time zone is "+0000". 6646 10. Author's Note 6648 This document is a revision or rewrite of earlier documents, and 6649 supercedes the protocol specification in those documents: RFC 3501, 6650 RFC 2060, RFC 1730, unpublished IMAP2bis.TXT document, RFC 1176, and 6651 RFC 1064. 6653 11. Security Considerations 6655 IMAP4rev2 protocol transactions, including electronic mail data, are 6656 sent in the clear over the network unless protection from snooping is 6657 negotiated. This can be accomplished either by the use of IMAPS 6658 service, STARTTLS command, negotiated privacy protection in the 6659 AUTHENTICATE command, or some other protection mechanism. 6661 11.1. STARTTLS Security Considerations 6663 IMAP client and server implementations MUST comply with relevant TLS 6664 recommendations from [RFC8314]. 6666 Clients and servers MUST implement TLS 1.2 [TLS-1.2] or newer. Use 6667 of TLS 1.3 [TLS-1.3] is RECOMMENDED. TLS 1.2 may be used only in 6668 cases where the other party has not yet implemented TLS 1.3. 6669 Additionally, when using TLS 1.2, IMAP implementations MUST implement 6670 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite, and SHOULD 6671 implement the TLS_RSA_WITH_AES_128_CBC_SHA [TLS-1.2] cipher suite. 6672 This is important as it assures that any two compliant 6673 implementations can be configured to interoperate. Other TLS cipher 6674 suites recommended in RFC 7525 are RECOMMENDED: 6675 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 6676 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 and 6677 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384. All other cipher suites are 6678 OPTIONAL. Note that this is a change from section 2.1 of [IMAP-TLS]. 6680 The list of mandatory-to-implement TLS 1.3 cipher suites is described 6681 in Section 9.1 of [TLS-1.3]. 6683 During the TLS negotiation [TLS-1.3][TLS-1.2], the client MUST check 6684 its understanding of the server hostname against the server's 6685 identity as presented in the server Certificate message, in order to 6686 prevent man-in-the-middle attacks. This procedure is described in 6687 [RFC7817]. 6689 Both the client and server MUST check the result of the STARTTLS 6690 command and subsequent TLS ([TLS-1.3][TLS-1.2]) negotiation to see 6691 whether acceptable authentication and/or privacy was achieved. 6693 11.2. COPYUID and APPENDUID response codes 6695 The COPYUID and APPENDUID response codes return information about the 6696 mailbox, which may be considered sensitive if the mailbox has 6697 permissions set that permit the client to COPY or APPEND to the 6698 mailbox, but not SELECT or EXAMINE it. 6700 Consequently, these response codes SHOULD NOT be issued if the client 6701 does not have access to SELECT or EXAMINE the mailbox. 6703 11.3. LIST command and Other Users' namespace 6705 In response to a LIST command containing an argument of the Other 6706 Users' Namespace prefix, a server SHOULD NOT list users that have not 6707 granted list access to their personal mailboxes to the currently 6708 authenticated user. Providing such a list, could compromise security 6709 by potentially disclosing confidential information of who is located 6710 on the server, or providing a starting point of a list of user 6711 accounts to attack. 6713 11.4. Other Security Considerations 6715 A server error message for an AUTHENTICATE command which fails due to 6716 invalid credentials SHOULD NOT detail why the credentials are 6717 invalid. 6719 Use of the LOGIN command sends passwords in the clear. This can be 6720 avoided by using the AUTHENTICATE command with a [SASL] mechanism 6721 that does not use plaintext passwords, by first negotiating 6722 encryption via STARTTLS or some other protection mechanism. 6724 A server implementation MUST implement a configuration that, at the 6725 time of authentication, requires: 6726 (1) The STARTTLS command has been negotiated. 6727 OR 6728 (2) Some other mechanism that protects the session from password 6729 snooping has been provided. 6730 OR 6731 (3) The following measures are in place: 6732 (a) The LOGINDISABLED capability is advertised, and [SASL] mechanisms 6733 (such as PLAIN) using plaintext passwords are NOT advertised in the 6734 CAPABILITY list. 6735 AND 6736 (b) The LOGIN command returns an error even if the password is 6737 correct. 6738 AND 6739 (c) The AUTHENTICATE command returns an error with all [SASL] 6740 mechanisms that use plaintext passwords, even if the password is 6741 correct. 6743 A server error message for a failing LOGIN command SHOULD NOT specify 6744 that the user name, as opposed to the password, is invalid. 6746 A server SHOULD have mechanisms in place to limit or delay failed 6747 AUTHENTICATE/LOGIN attempts. 6749 Additional security considerations are discussed in the section 6750 discussing the AUTHENTICATE (see Section 6.2.2) and LOGIN (see 6751 Section 6.2.3) commands. 6753 12. IANA Considerations 6755 IANA is requested to update "Service Names and Transport Protocol 6756 Port Numbers" registry as follows: 6758 1. Registration for TCP port 143 and the corresponding "imap" 6759 service name should be updated to point to this document and RFC 6760 3501. 6762 2. Registration for TCP port 993 and the corresponding "imaps" 6763 service name should be updated to point to this document, RFC 6764 8314 and RFC 3501. 6766 3. Both UDP port 143 and UDP port 993 should be marked as "Reserved" 6767 in the registry. 6769 Additional IANA actions are specified in subsection of this section. 6771 12.1. Updates to IMAP4 Capabilities registry 6773 IMAP4 capabilities are registered by publishing a standards track or 6774 IESG approved informational or experimental RFC. The registry is 6775 currently located at: https://www.iana.org/assignments/ 6776 imap4-capabilities 6778 As this specification revises the AUTH= prefix, STARTTLS and 6779 LOGINDISABLED extensions, IANA is requested to update registry 6780 entries for these 3 extensions to point to this document. 6782 12.2. GSSAPI/SASL service name 6784 GSSAPI/Kerberos/SASL service names are registered by publishing a 6785 standards track or IESG approved experimental RFC. The registry is 6786 currently located at: https://www.iana.org/assignments/gssapi- 6787 service-names 6789 IANA is requested to update the "imap" service name previously 6790 registered in RFC 3501, to point to this document. 6792 12.3. LIST Selection Options, LIST Return Options, LIST extended data 6793 items 6795 [RFC5258] specifies IANA registration procedures for LIST Selection 6796 Options, LIST Return Options, LIST extended data items. This 6797 document doesn't change these registration procedures. In particular 6798 LIST selection options Section 6.3.9.1 and LIST return options 6799 Section 6.3.9.2 are registered using the procedure specified in 6800 Section 9 of [RFC5258] (and using the registration template from 6801 Section 9.3 of [RFC5258]). LIST Extended Data Items are registered 6802 using the registration template from Section 9.6 of [RFC5258]). 6804 IANA is requested to add a reference to [RFCXXXX] for the "OLDNAME" 6805 LIST-EXTENDED extended data item entry. This is in addition to the 6806 existing reference to [RFC5465]. 6808 13. References 6810 13.1. Normative References 6812 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access 6813 Protocol version 4 - LIST Command Extensions", RFC 5258, 6814 DOI 10.17487/RFC5258, June 2008, 6815 . 6817 [RFC5788] Melnikov, A. and D. Cridland, "IMAP4 Keyword Registry", 6818 RFC 5788, DOI 10.17487/RFC5788, March 2010, 6819 . 6821 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6822 Specifications: ABNF", STD 68, RFC 5234, January 2008, 6823 . 6825 [ANONYMOUS] 6826 Zeilenga, K., "Anonymous Simple Authentication and 6827 Security Layer (SASL) Mechanism", RFC 4505, June 2006, 6828 . 6830 [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration 6831 Procedures", BCP 19, RFC 2978, October 2000, 6832 . 6834 [SCRAM-SHA-256] 6835 Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple 6836 Authentication and Security Layer (SASL) Mechanisms", 6837 RFC 7677, DOI 10.17487/RFC7677, November 2015, 6838 . 6840 [DISPOSITION] 6841 Troost, R., Dorner, S., and K. Moore, Ed., "Communicating 6842 Presentation Information in Internet Messages: The 6843 Content-Disposition Header Field", RFC 2183, August 1997, 6844 . 6846 [PLAIN] Zeilenga, K., Ed., "The PLAIN Simple Authentication and 6847 Security Layer (SASL) Mechanism", RFC 4616, August 2006, 6848 . 6850 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6851 Requirement Levels", BCP 14, RFC 2119, 6852 DOI 10.17487/RFC2119, March 1997, 6853 . 6855 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 6856 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 6857 May 2017, . 6859 [LANGUAGE-TAGS] 6860 Alvestrand, H., "Content Language Headers", RFC 3282, May 6861 2002, . 6863 [LOCATION] 6864 Palme, J., Hopmann, A., and N. Shelness, "MIME 6865 Encapsulation of Aggregate Documents, such as HTML 6866 (MHTML)", RFC 2557, March 1999, 6867 . 6869 [MD5] Myers, J. and M. Rose, "The Content-MD5 Header Field", 6870 RFC 1864, October 1995, 6871 . 6873 [MIME-HDRS] 6874 Moore, K., "MIME (Multipurpose Internet Mail Extensions) 6875 Part Three: Message Header Extensions for Non-ASCII Text", 6876 RFC 2047, November 1996, 6877 . 6879 [MIME-IMB] 6880 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6881 Extensions (MIME) Part One: Format of Internet Message 6882 Bodies", RFC 2045, November 1996, 6883 . 6885 [MIME-IMT] 6886 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6887 Extensions (MIME) Part Two: Media Types", RFC 2046, 6888 November 1996, . 6890 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 6891 Word Extensions: Character Sets, Languages, and 6892 Continuations", RFC 2231, DOI 10.17487/RFC2231, November 6893 1997, . 6895 [RFC-5322] 6896 Resnick, P., Ed., "Internet Message Format", RFC 5322, 6897 October 2008, . 6899 [SASL] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 6900 Authentication and Security Layer (SASL)", RFC 4422, June 6901 2006, . 6903 [TLS-1.2] Dierks, T. and E. Rescorla, "The Transport Layer Security 6904 (TLS) Protocol Version 1.2", RFC 5246, August 2008, 6905 . 6907 [TLS-1.3] Rescorla, E., "The Transport Layer Security (TLS) Protocol 6908 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 6909 . 6911 [UTF-7] Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe 6912 Transformation Format of Unicode", RFC 2152, May 1997, 6913 . 6915 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 6916 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 6917 2003, . 6919 [MULTIAPPEND] 6920 Crispin, M., "Internet Message Access Protocol (IMAP) - 6921 MULTIAPPEND Extension", RFC 3502, March 2003, 6922 . 6924 [NET-UNICODE] 6925 Klensin, J. and M. Padlipsky, "Unicode Format for Network 6926 Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008, 6927 . 6929 [I18N-HDRS] 6930 Yang, A., Steele, S., and N. Freed, "Internationalized 6931 Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 6932 2012, . 6934 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 6935 Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, 6936 . 6938 [RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS) 6939 Server Identity Check Procedure for Email-Related 6940 Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016, 6941 . 6943 [RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition 6944 Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, 6945 February 2017, . 6947 [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: 6948 Use of Transport Layer Security (TLS) for Email Submission 6949 and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, 6950 . 6952 [IMAP-IMPLEMENTATION] 6953 Leiba, B., "IMAP4 Implementation Recommendations", 6954 RFC 2683, September 1999, 6955 . 6957 [IMAP-MULTIACCESS] 6958 Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", 6959 RFC 2180, July 1997, 6960 . 6962 13.2. Informative References (related protocols) 6964 [RFC3503] Melnikov, A., "Message Disposition Notification (MDN) 6965 profile for Internet Message Access Protocol (IMAP)", 6966 RFC 3503, DOI 10.17487/RFC3503, March 2003, 6967 . 6969 [RFC5256] Crispin, M. and K. Murchison, "Internet Message Access 6970 Protocol - SORT and THREAD Extensions", RFC 5256, 6971 DOI 10.17487/RFC5256, June 2008, 6972 . 6974 [RFC2193] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 6975 DOI 10.17487/RFC2193, September 1997, 6976 . 6978 [RFC3348] Gahrns, M. and R. Cheng, "The Internet Message Action 6979 Protocol (IMAP4) Child Mailbox Extension", RFC 3348, 6980 DOI 10.17487/RFC3348, July 2002, 6981 . 6983 [RFC5465] Gulbrandsen, A., King, C., and A. Melnikov, "The IMAP 6984 NOTIFY Extension", RFC 5465, DOI 10.17487/RFC5465, 6985 February 2009, . 6987 [RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals", 6988 RFC 7888, DOI 10.17487/RFC7888, May 2016, 6989 . 6991 [IMAP-DISC] 6992 Melnikov, A., Ed., "Synchronization Operations for 6993 Disconnected IMAP4 Clients", RFC 4549, June 2006, 6994 . 6996 [IMAP-I18N] 6997 Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 6998 Message Access Protocol Internationalization", RFC 5255, 6999 DOI 10.17487/RFC5255, June 2008, 7000 . 7002 [IMAP-MODEL] 7003 Crispin, M., "Distributed Electronic Mail Models in 7004 IMAP4", RFC 1733, December 1994, 7005 . 7007 [IMAP-UTF-8] 7008 Resnick, P., Ed., Newman, C., Ed., and S. Shen, Ed., "IMAP 7009 Support for UTF-8", RFC 6855, DOI 10.17487/RFC6855, March 7010 2013, . 7012 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 7013 October 2008, . 7015 [RFC3516] Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516, 7016 DOI 10.17487/RFC3516, April 2003, 7017 . 7019 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 7020 RFC 4314, December 2005, 7021 . 7023 [RFC2087] Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 7024 1997, . 7026 [IMAP-URL] 7027 Melnikov, A., Ed. and C. Newman, "IMAP URL Scheme", 7028 RFC 5092, DOI 10.17487/RFC5092, November 2007, 7029 . 7031 [IMAP-KEYWORDS-REG] 7032 IANA, "IMAP and JMAP Keywords", December 2009, 7033 . 7036 [IMAP-MAILBOX-NAME-ATTRS-REG] 7037 IANA, "IMAP Mailbox Name Attributes", June 2018, 7038 . 7041 [CHARSET-REG] 7042 IANA, "Character Set Registrations", May 2015, 7043 . 7046 13.3. Informative References (historical aspects of IMAP and related 7047 protocols) 7049 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 7050 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003, 7051 . 7053 [IMAP-COMPAT] 7054 Crispin, M., "IMAP4 Compatibility with IMAP2bis", 7055 RFC 2061, December 1996, 7056 . 7058 [IMAP-HISTORICAL] 7059 Crispin, M., "IMAP4 Compatibility with IMAP2 and 7060 IMAP2bis", RFC 1732, December 1994, 7061 . 7063 [IMAP-OBSOLETE] 7064 Crispin, M., "Internet Message Access Protocol - Obsolete 7065 Syntax", RFC 2062, December 1996, 7066 . 7068 [IMAP2] Crispin, M., "Interactive Mail Access Protocol: Version 7069 2", RFC 1176, August 1990, 7070 . 7072 [RFC-822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET 7073 TEXT MESSAGES", STD 11, RFC 822, August 1982, 7074 . 7076 [IMAP-TLS] 7077 Newman, C., "Using TLS with IMAP, POP3 and ACAP", 7078 RFC 2595, June 1999, 7079 . 7081 Appendix A. Backward compatibility with IMAP4rev1 7083 An implementation that wants to remain compatible with IMAP4rev1 can 7084 advertise both IMAP4rev1 and IMAP4rev2 in its CAPABILITY response/ 7085 response code. While some IMAP4rev1 responses were removed in 7086 IMAP4rev2, their presence will not break IMAP4rev2-only clients. 7088 If both IMAP4rev1 and IMAP4rev2 are advertised, an IMAP client that 7089 wants to use IMAP4rev2 MUST issue an "ENABLE IMAP4rev2" command. 7091 Servers advertising both IMAP4rev1 and IMAP4rev2 MUST NOT generate 7092 UTF-8 quoted strings unless the client has issued "ENABLE IMAP4rev2". 7094 Consider implementation of mechanisms described or referenced in 7095 [IMAP-UTF-8] to achieve this goal. 7097 Servers advertising both IMAP4rev1 and IMAP4rev2, and clients 7098 intending to be compatible with IMAP4rev1 servers MUST be compatible 7099 with the international mailbox naming convention described in the 7100 following subsection. 7102 A.1. Mailbox International Naming Convention for compatibility with 7103 IMAP4rev1 7105 Support for the Mailbox International Naming Convention described in 7106 this section is not required for IMAP4rev2-only clients and servers. 7107 It is only used for backward compatibility with IMAP4rev1 7108 implementations. 7110 By convention, international mailbox names in IMAP4rev1 are specified 7111 using a modified version of the UTF-7 encoding described in [UTF-7]. 7112 Modified UTF-7 may also be usable in servers that implement an 7113 earlier version of this protocol. 7115 In modified UTF-7, printable US-ASCII characters, except for "&", 7116 represent themselves; that is, characters with octet values 0x20-0x25 7117 and 0x27-0x7e. The character "&" (0x26) is represented by the two- 7118 octet sequence "&-". 7120 All other characters (octet values 0x00-0x1f and 0x7f-0xff) are 7121 represented in modified BASE64, with a further modification from 7122 [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be 7123 used to represent any printing US-ASCII character which can represent 7124 itself. Only characters inside the modified BASE64 alphabet are 7125 permitted in modified BASE64 text. 7127 "&" is used to shift to modified BASE64 and "-" to shift back to US- 7128 ASCII. There is no implicit shift from BASE64 to US-ASCII, and null 7129 shifts ("-&" while in BASE64; note that "&-" while in US-ASCII means 7130 "&") are not permitted. However, all names start in US-ASCII, and 7131 MUST end in US-ASCII; that is, a name that ends with a non-ASCII 7132 ISO-10646 character MUST end with a "-"). 7134 The purpose of these modifications is to correct the following 7135 problems with UTF-7: 7137 1. UTF-7 uses the "+" character for shifting; this conflicts with 7138 the common use of "+" in mailbox names, in particular USENET 7139 newsgroup names. 7141 2. UTF-7's encoding is BASE64 which uses the "/" character; this 7142 conflicts with the use of "/" as a popular hierarchy delimiter. 7144 3. UTF-7 prohibits the unencoded usage of "\"; this conflicts with 7145 the use of "\" as a popular hierarchy delimiter. 7147 4. UTF-7 prohibits the unencoded usage of "~"; this conflicts with 7148 the use of "~" in some servers as a home directory indicator. 7150 5. UTF-7 permits multiple alternate forms to represent the same 7151 string; in particular, printable US-ASCII characters can be 7152 represented in encoded form. 7154 Although modified UTF-7 is a convention, it establishes certain 7155 requirements on server handling of any mailbox name with an embedded 7156 "&" character. In particular, server implementations MUST preserve 7157 the exact form of the modified BASE64 portion of a modified UTF-7 7158 name and treat that text as case-sensitive, even if names are 7159 otherwise case-insensitive or case-folded. 7161 Server implementations SHOULD verify that any mailbox name with an 7162 embedded "&" character, used as an argument to CREATE, is: in the 7163 correctly modified UTF-7 syntax, has no superfluous shifts, and has 7164 no encoding in modified BASE64 of any printing US-ASCII character 7165 which can represent itself. However, client implementations MUST NOT 7166 depend upon the server doing this, and SHOULD NOT attempt to create a 7167 mailbox name with an embedded "&" character unless it complies with 7168 the modified UTF-7 syntax. 7170 Server implementations which export a mail store that does not follow 7171 the modified UTF-7 convention MUST convert to modified UTF-7 any 7172 mailbox name that contains either non-ASCII characters or the "&" 7173 character. 7175 For example, here is a mailbox name which mixes English, Chinese, 7176 and Japanese text: ~peter/mail/&U,BTFw-/&ZeVnLIqe- 7178 For example, the string "&Jjo!" is not a valid mailbox name 7179 because it does not contain a shift to US-ASCII before the "!". 7180 The correct form is "&Jjo-!". The string "&U,BTFw-&ZeVnLIqe-" is 7181 not permitted because it contains a superfluous shift. The 7182 correct form is "&U,BTF2XlZyyKng-". 7184 Appendix B. Backward compatibility with BINARY extension 7186 IMAP4rev2 is incorporates subset of functionality provided by the 7187 BINARY extension [RFC3516], in particular it includes additional 7188 FETCH items (BINARY, BINARY.PEEK and BINARY.SIZE), but not extensions 7189 to the APPEND command. IMAP4rev2 implementations that supports full 7190 RFC 3516 functionality need to also advertise the BINARY token in the 7191 CAPABILITY response. 7193 Appendix C. Backward compatibility with LIST-EXTENDED extension 7195 IMAP4rev2 is incorporates most of functionality provided by the LIST- 7196 EXTENDED extension [RFC5258]. In particular, multiple mailbox 7197 patterns syntax is not supported in IMAP4rev2, unless LIST-EXTENDED 7198 capability is also advertised in CAPABILITY response/response code. 7200 Appendix D. Changes from RFC 3501 / IMAP4rev1 7202 Below is the summary of changes since RFC 3501: 7204 1. Folded in IMAP NAMESPACE (RFC 2342), UNSELECT (RFC 3691), 7205 UIDPLUS (RFC 4315), ESEARCH (RFC 4731), SEARCHRES (RFC 5182), 7206 ENABLE (RFC 5161), IDLE (RFC 2177), SASL-IR (RFC 4959), LIST- 7207 EXTENDED (RFC 5258), LIST-STATUS (RFC 5819), MOVE (RFC 6851) and 7208 LITERAL- (RFC 7888) extensions. Also folded RFC 4466 (IMAP ABNF 7209 extensions), RFC 5530 (response codes), the FETCH side of the 7210 BINARY extension (RFC 3516) and the list of new mailbox 7211 attributes from SPECIAL-USE (RFC 6154). 7213 2. Added STATUS SIZE (RFC 8438) and STATUS DELETED. 7215 3. SEARCH command now requires to return ESEARCH response (SEARCH 7216 response is now deprecated). 7218 4. Clarified which SEARCH keys has to use substring match and which 7219 don't. 7221 5. Clarified that server should decode parameter value 7222 continuations as described in [RFC2231]. This requirement was 7223 hidden in RFC 2231 itself. 7225 6. Added CLOSED response code from RFC 7162. SELECT/EXAMINE when a 7226 mailbox is already selected now require for the CLOSED response 7227 code to be returned. 7229 7. SELECT/EXAMINE are now required to return untagged LIST 7230 response. 7232 8. UNSEEN response code on SELECT/EXAMINE is now deprecated. 7234 9. RECENT response on SELECT/EXAMINE, \Recent flag, RECENT STATUS, 7235 SEARCH NEW items are now deprecated. 7237 10. Clarified that the server doesn't need to send a new 7238 PERMANENTFLAGS response code when a new keyword was successfully 7239 added and the server advertised \* earlier for the same mailbox. 7241 11. For future extensibility extended ABNF for tagged-ext-simple to 7242 allow for bare number64. 7244 12. Added SHOULD level requirement on IMAP servers to support 7245 $MDNSent, $Forwarded, $Junk, $NonJunk and $Phishing keywords. 7247 13. Mailbox names and message headers now allow for UTF-8. Support 7248 for Modified UTF-7 in mailbox names is not required, unless 7249 compatibility with IMAP4rev1 is desired. 7251 14. Removed the CHECK command. Clients should use NOOP instead. 7253 15. RFC822, RFC822.HEADER and RFC822.TEXT FETCH data items were 7254 deprecated. Clients should use the corresponding BODY[] 7255 variants instead. 7257 16. LSUB command was deprecated. Clients should use LIST 7258 (SUBSCRIBED) instead. 7260 17. IDLE command can now return updates not related to the currently 7261 selected mailbox state. 7263 18. All unsolicited FETCH updates are required to include UID. 7265 19. Clarified that client implementations MUST ignore response codes 7266 that they do not recognize. (Change from a SHOULD to a MUST.) 7268 20. resp-text ABNF non terminal was updated to allow for empty text. 7270 21. After ENABLE IMAP4rev2 human readable response text can include 7271 non ASCII encoded in UTF-8. 7273 22. Updated to use modern TLS-related recommendations as per RFC 7274 8314, RFC 7817, RFC 7525. 7276 23. Replaced DIGEST-MD5 SASL mechanism with SCRAM-SHA-256. DIGEST- 7277 MD5 was deprecated. 7279 Appendix E. Other Recommended IMAP Extensions 7281 Support for the following extensions is recommended for all IMAP 7282 client and servers. Why they significantly reduce bandwidth and/or 7283 number of round trips used by IMAP in certain situations, the EXTRA 7284 WG decided that requiring them as a part of IMAP4rev2 would push the 7285 bar to implement too high for new implementations. Also note that 7286 absence of any IMAP extension from this list doesn't make it somehow 7287 deficient or not recommended for use with IMAP4rev2. 7289 1. QRESYNC and CONDSTORE extensions (RFC 7162). They make 7290 discovering changes to IMAP mailboxes more efficient, at the 7291 expense of storing a bit more state. 7293 2. OBJECTID extension (RFC 8474) helps with preserving IMAP client 7294 cache when messages moved/copied or mailboxes are renamed. 7296 Appendix F. Acknowledgement 7298 Earlier versions of this document were edited by Mark Crispin. 7299 Sadly, he is no longer available to help with this work. Editors of 7300 this revisions are hoping that Mark would have approved. 7302 Chris Newman has contributed text on I18N and use of UTF-8 in 7303 messages and mailbox names. 7305 Thank you to Tony Hansen for helping with the index generation. 7306 Thank you to Timo Sirainen, Bron Gondwana, Stephan Bosch and Arnt 7307 Gulbrandsen for extensive feedback. 7309 This document incorporate text from RFC 4315 (by Mark Crispin), RFC 7310 4466 (by Cyrus Daboo), RFC 4731 (by Dave Cridland), RFC 5161 (by Arnt 7311 Gulbrandsen), RFC 5465 (by Arnt Gulbrandsen and Curtis King), RFC 7312 5530 (by Arnt Gulbrandsen), RFC 5819 (by Timo Sirainen), RFC 6154 (by 7313 Jamie Nicolson), RFC 8438 (by Stephan Bosch) so work done by authors/ 7314 editors of these documents is appreciated. Note that editors of this 7315 document were redacted from the above list. 7317 The CHILDREN return option was originally proposed by Mike Gahrns and 7318 Raymond Cheng in [RFC3348]. Most of the information in 7319 Section 6.3.9.5 is taken directly from their original specification 7320 [RFC3348]. 7322 Index 7324 $ 7325 $Forwarded (predefined flag) 12 7326 $Junk (predefined flag) 12 7327 $MDNSent (predefined flag) 12 7328 $NotJunk (predefined flag) 12 7329 $Phishing (predefined flag) 13 7331 + 7332 +FLAGS 92 7333 +FLAGS.SILENT 92 7335 - 7336 -FLAGS 92 7337 -FLAGS.SILENT 92 7339 A 7340 ALERT (response code) 99 7341 ALL (fetch item) 88 7342 ALL (search key) 78 7343 ALL (search result option) 76 7344 ALREADYEXISTS (response code) 99 7345 ANSWERED (search key) 78 7346 APPEND (command) 68 7347 APPENDUID (response code) 100 7348 AUTHENTICATE (command) 29 7349 AUTHENTICATIONFAILED (response code) 100 7350 AUTHORIZATIONFAILED (response code) 101 7352 B 7353 BAD (response) 108 7354 BADCHARSET (response code) 101 7355 BCC (search key) 78 7356 BEFORE (search key) 78 7357 BINARY.PEEK[]<> (fetch item) 88 7358 BINARY.SIZE[] (fetch item) 89 7359 BINARY.SIZE[] (fetch result) 118 7360 BINARY[]<> (fetch result) 118 7361 BINARY[]<> (fetch item) 88 7362 BODY (fetch item) 89 7363 BODY (fetch result) 119 7364 BODY (search key) 78 7365 BODY.PEEK[
]<> (fetch item) 89 7366 BODYSTRUCTURE (fetch item) 90 7367 BODYSTRUCTURE (fetch result) 119 7368 BODY[
]<> (fetch result) 119 7369 BODY[
]<> (fetch item) 89 7370 BYE (response) 109 7371 Body Structure (message attribute) 14 7373 C 7374 CANNOT (response code) 101 7375 CAPABILITY (command) 25 7376 CAPABILITY (response code) 101 7377 CAPABILITY (response) 110 7378 CC (search key) 78 7379 CLIENTBUG (response code) 101 7380 CLOSE (command) 74 7381 CLOSED (response code) 102 7382 CONTACTADMIN (response code) 102 7383 COPY (command) 93 7384 COPYUID (response code) 102 7385 CORRUPTION (response code) 103 7386 COUNT (search result option) 76 7387 CREATE (command) 38 7389 D 7390 DELETE (command) 39 7391 DELETED (search key) 78 7392 DELETED (status item) 68 7393 DRAFT (search key) 78 7395 E 7396 ENABLE (command) 33 7397 ENVELOPE (fetch item) 90 7398 ENVELOPE (fetch result) 122 7399 ESEARCH (response) 115 7400 EXAMINE (command) 37 7401 EXPIRED (response code) 103 7402 EXPUNGE (command) 75 7403 EXPUNGE (response) 117 7404 EXPUNGEISSUED (response code) 103 7405 Envelope Structure (message attribute) 14 7407 F 7408 FAST (fetch item) 88 7409 FETCH (command) 87 7410 FETCH (response) 118 7411 FLAGGED (search key) 78 7412 FLAGS (fetch item) 90 7413 FLAGS (fetch result) 123 7414 FLAGS (response) 116 7415 FLAGS (store command data item) 92 7416 FLAGS.SILENT (store command data item) 92 7417 FROM (search key) 79 7418 FULL (fetch item) 88 7419 Flags (message attribute) 11 7421 H 7422 HASCHILDREN (response code) 103 7423 HEADER (part specifier) 90 7424 HEADER (search key) 79 7425 HEADER.FIELDS (part specifier) 90 7426 HEADER.FIELDS.NOT (part specifier) 90 7428 I 7429 IDLE (command) 71 7430 INTERNALDATE (fetch item) 90 7431 INTERNALDATE (fetch result) 123 7432 INUSE (response code) 104 7433 Internal Date (message attribute) 13 7435 K 7436 KEYWORD (search key) 79 7437 Keyword (type of flag) 12 7439 L 7440 LARGER (search key) 79 7441 LIMIT (response code) 104 7442 LIST (command) 44 7443 LIST (response) 111 7444 LOGOUT (command) 27 7446 M 7447 MAX (search result option) 76 7448 MAY (specification requirement term) 5 7449 MESSAGES (status item) 68 7450 MIME (part specifier) 91 7451 MIN (search result option) 76 7452 MOVE (command) 94 7453 MUST (specification requirement term) 5 7454 MUST NOT (specification requirement term) 5 7455 Message Sequence Number (message attribute) 11 7457 N 7458 NAMESPACE (command) 62 7459 NAMESPACE (response) 115 7460 NO (response) 108 7461 NONEXISTENT (response code) 104 7462 NOOP (command) 26 7463 NOPERM (response code) 104 7464 NOT (search key) 79 7465 NOT RECOMMENDED (specification requirement term) 5 7467 O 7468 OK (response) 107 7469 ON (search key) 79 7470 OPTIONAL (specification requirement term) 5 7471 OR (search key) 79 7472 OVERQUOTA (response code) 104 7474 P 7475 PARSE (response code) 105 7476 PERMANENTFLAGS (response code) 105 7477 PREAUTH (response) 108 7478 PRIVACYREQUIRED (response code) 105 7479 Permanent Flag (class of flag) 13 7480 Predefined keywords 12 7482 R 7483 READ-ONLY (response code) 106 7484 READ-WRITE (response code) 106 7485 RECOMMENDED (specification requirement term) 5 7486 RENAME (command) 41 7487 REQUIRED (specification requirement term) 5 7488 RFC822.SIZE (fetch item) 90 7489 RFC822.SIZE (fetch result) 123 7491 S 7492 SAVE (search result option) 76 7493 SEARCH (command) 75 7494 SEEN (search key) 79 7495 SELECT (command) 35 7496 SENTBEFORE (search key) 79 7497 SENTON (search key) 79 7498 SENTSINCE (search key) 79 7499 SERVERBUG (response code) 106 7500 SHOULD (specification requirement term) 5 7501 SHOULD NOT (specification requirement term) 5 7502 SINCE (search key) 79 7503 SIZE (status item) 68 7504 SMALLER (search key) 79 7505 STARTTLS (command) 28 7506 STATUS (command) 67 7507 STATUS (response) 115 7508 STORE (command) 92 7509 SUBJECT (search key) 80 7510 SUBSCRIBE (command) 43 7511 Session Flag (class of flag) 13 7512 System Flag (type of flag) 11 7514 T 7515 TEXT (part specifier) 90 7516 TEXT (search key) 80 7517 TO (search key) 80 7518 TRYCREATE (response code) 106 7520 U 7521 UID (command) 96 7522 UID (fetch item) 90 7523 UID (fetch result) 123 7524 UID (search key) 80 7525 UIDNEXT (response code) 106 7526 UIDNEXT (status item) 68 7527 UIDNOTSTICKY (response code) 106 7528 UIDVALIDITY (response code) 107 7529 UIDVALIDITY (status item) 68 7530 UNANSWERED (search key) 80 7531 UNAVAILABLE (response code) 107 7532 UNDELETED (search key) 80 7533 UNDRAFT (search key) 80 7534 UNFLAGGED (search key) 80 7535 UNKEYWORD (search key) 80 7536 UNKNOWN-CTE (response code) 107 7537 UNSEEN (search key) 80 7538 UNSEEN (status item) 68 7539 UNSELECT (command) 74 7540 UNSUBSCRIBE (command) 44 7541 Unique Identifier (UID) (message attribute) 9 7543 X 7544 X (command) 97 7546 [ 7547 [RFC-5322] Size (message attribute) 14 7549 \ 7550 \All (mailbox name attribute) 113 7551 \Answered (system flag) 12 7552 \Archive (mailbox name attribute) 113 7553 \Deleted (system flag) 12 7554 \Draft (system flag) 12 7555 \Drafts (mailbox name attribute) 113 7556 \Flagged (mailbox name attribute) 113 7557 \Flagged (system flag) 12 7558 \HasChildren (mailbox name attribute) 112 7559 \HasNoChildren (mailbox name attribute) 112 7560 \Junk (mailbox name attribute) 113 7561 \Marked (mailbox name attribute) 112 7562 \Noinferiors (mailbox name attribute) 111 7563 \NonExistent (mailbox name attribute) 111 7564 \Noselect (mailbox name attribute) 111 7565 \Recent (system flag) 12 7566 \Remote (mailbox name attribute) 112 7567 \Seen (system flag) 12 7568 \Sent (mailbox name attribute) 113 7569 \Subscribed (mailbox name attribute) 112 7570 \Trash (mailbox name attribute) 113 7571 \Unmarked (mailbox name attribute) 112 7573 Authors' Addresses 7575 Alexey Melnikov (editor) 7576 Isode Ltd 7577 14 Castle Mews 7578 Hampton, Middlesex TW12 2NP 7579 UK 7581 Email: Alexey.Melnikov@isode.com 7583 Barry Leiba (editor) 7584 Futurewei Technologies 7586 Phone: +1 646 827 0648 7587 Email: barryleiba@computer.org 7588 URI: http://internetmessagingtechnology.org/