idnits 2.17.00 (12 Aug 2021) /tmp/idnits60788/draft-ietf-extra-imap4rev2-19.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 7067, but not defined == Missing Reference: 'IMAP-OBSOLETE' is mentioned on line 7062, but not defined == Missing Reference: 'IMAP-COMPAT' is mentioned on line 7052, but not defined == Missing Reference: 'IMAP-HISTORICAL' is mentioned on line 7057, but not defined == Missing Reference: 'RFC-822' is mentioned on line 7071, but not defined ** Obsolete undefined reference: RFC 822 (Obsoleted by RFC 2822) == Missing Reference: 'IMAP-MODEL' is mentioned on line 7001, but not defined == Missing Reference: 'IMAP-DISC' is mentioned on line 6990, but not defined == Missing Reference: 'RFC3503' is mentioned on line 6963, but not defined == Missing Reference: 'IMAP-KEYWORDS-REG' is mentioned on line 7030, but not defined == Missing Reference: 'SMTP' is mentioned on line 7011, but not defined == Missing Reference: 'RFC7888' is mentioned on line 6986, but not defined -- Looks like a reference, but probably isn't: '1' on line 891 == Missing Reference: 'IMAP-URL' is mentioned on line 7025, but not defined == Missing Reference: 'TLS' is mentioned on line 1196, but not defined == Missing Reference: 'UIDVALIDITY 3857529045' is mentioned on line 5768, but not defined == Missing Reference: 'UIDNEXT 4392' is mentioned on line 1733, but not defined == Missing Reference: 'RFC2193' is mentioned on line 6973, but not defined == Missing Reference: 'RFC3348' is mentioned on line 7319, but not defined ** Obsolete undefined reference: RFC 3348 (Obsoleted by RFC 5258) == Missing Reference: 'RFC4314' is mentioned on line 7018, but not defined == Missing Reference: 'RFC3501' is mentioned on line 7048, but not defined ** Obsolete undefined reference: RFC 3501 (Obsoleted by RFC 9051) == Missing Reference: 'UIDNEXT 2' is mentioned on line 3263, but not defined == Missing Reference: 'UIDVALIDITY 1' is mentioned on line 3335, but not defined == Missing Reference: 'CHARSET-REG' is mentioned on line 7040, but not defined == Missing Reference: 'IMAP-I18N' is mentioned on line 6995, but not defined == Missing Reference: 'HEADER' is mentioned on line 5786, but not defined == Missing Reference: 'BADCHARSET UTF-8' is mentioned on line 3915, but not defined == Missing Reference: 'UID' is mentioned on line 4343, but not defined == Missing Reference: 'RFC2087' is mentioned on line 7022, but not defined ** Obsolete undefined reference: RFC 2087 (Obsoleted by RFC 9208) == Missing Reference: 'IMAP-MAILBOX-NAME-ATTRS-REG' is mentioned on line 7035, but not defined == Missing Reference: 'READ-WRITE' is mentioned on line 5770, but not defined == Missing Reference: 'RFC4422' is mentioned on line 6117, but not defined == Missing Reference: 'IMAP4' is mentioned on line 6202, but not defined == Missing Reference: 'Namespace-Response-Extensions' is mentioned on line 6272, but not defined == Missing Reference: 'IMAP-TLS' is mentioned on line 7075, but not defined == Missing Reference: 'RFCXXXX' is mentioned on line 6803, but not defined == Missing Reference: 'RFC5465' is mentioned on line 6982, but not defined == Missing Reference: 'RFC5256' is mentioned on line 6968, but not defined == Missing Reference: 'IMAP-UTF-8' is mentioned on line 7094, but not defined == Missing Reference: 'RFC3516' is mentioned on line 7186, 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-imap4rev2-19 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 RFC 6409. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at https://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on April 30, 2021. 48 Copyright Notice 50 Copyright (c) 2020 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (https://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 This document may contain material from IETF Documents or IETF 64 Contributions published or made publicly available before November 65 10, 2008. The person(s) controlling the copyright in some of this 66 material may not have granted the IETF Trust the right to allow 67 modifications of such material outside the IETF Standards Process. 68 Without obtaining an adequate license from the person(s) controlling 69 the copyright in such materials, this document may not be modified 70 outside the IETF Standards Process, and derivative works of it may 71 not be created outside the IETF Standards Process, except to format 72 it for publication as an RFC or to translate it into languages other 73 than English. 75 Table of Contents 77 1. How to Read This Document . . . . . . . . . . . . . . . . . . 5 78 1.1. Organization of This Document . . . . . . . . . . . . . . 5 79 1.2. Conventions Used in This Document . . . . . . . . . . . . 5 80 1.3. Special Notes to Implementors . . . . . . . . . . . . . . 6 81 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 82 2.1. Link Level . . . . . . . . . . . . . . . . . . . . . . . 7 83 2.2. Commands and Responses . . . . . . . . . . . . . . . . . 7 84 2.2.1. Client Protocol Sender and Server Protocol Receiver . 7 85 2.2.2. Server Protocol Sender and Client Protocol Receiver . 8 86 2.3. Message Attributes . . . . . . . . . . . . . . . . . . . 9 87 2.3.1. Message Numbers . . . . . . . . . . . . . . . . . . . 9 88 2.3.2. Flags Message Attribute . . . . . . . . . . . . . . . 11 89 2.3.3. Internal Date Message Attribute . . . . . . . . . . . 13 90 2.3.4. [RFC-5322] Size Message Attribute . . . . . . . . . . 14 91 2.3.5. Envelope Structure Message Attribute . . . . . . . . 14 92 2.3.6. Body Structure Message Attribute . . . . . . . . . . 14 93 2.4. Message Texts . . . . . . . . . . . . . . . . . . . . . . 14 94 3. State and Flow Diagram . . . . . . . . . . . . . . . . . . . 14 95 3.1. Not Authenticated State . . . . . . . . . . . . . . . . . 14 96 3.2. Authenticated State . . . . . . . . . . . . . . . . . . . 15 97 3.3. Selected State . . . . . . . . . . . . . . . . . . . . . 15 98 3.4. Logout State . . . . . . . . . . . . . . . . . . . . . . 15 99 4. Data Formats . . . . . . . . . . . . . . . . . . . . . . . . 17 100 4.1. Atom . . . . . . . . . . . . . . . . . . . . . . . . . . 17 101 4.1.1. Sequence set and UID set . . . . . . . . . . . . . . 17 102 4.2. Number . . . . . . . . . . . . . . . . . . . . . . . . . 17 103 4.3. String . . . . . . . . . . . . . . . . . . . . . . . . . 17 104 4.3.1. 8-bit and Binary Strings . . . . . . . . . . . . . . 18 105 4.4. Parenthesized List . . . . . . . . . . . . . . . . . . . 19 106 4.5. NIL . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 107 5. Operational Considerations . . . . . . . . . . . . . . . . . 20 108 5.1. Mailbox Naming . . . . . . . . . . . . . . . . . . . . . 20 109 5.1.1. Mailbox Hierarchy Naming . . . . . . . . . . . . . . 21 110 5.1.2. Namespaces . . . . . . . . . . . . . . . . . . . . . 21 111 5.2. Mailbox Size and Message Status Updates . . . . . . . . . 23 112 5.3. Response when no Command in Progress . . . . . . . . . . 23 113 5.4. Autologout Timer . . . . . . . . . . . . . . . . . . . . 23 114 5.5. Multiple Commands in Progress (Command Pipelining) . . . 23 115 6. Client Commands . . . . . . . . . . . . . . . . . . . . . . . 25 116 6.1. Client Commands - Any State . . . . . . . . . . . . . . . 25 117 6.1.1. CAPABILITY Command . . . . . . . . . . . . . . . . . 25 118 6.1.2. NOOP Command . . . . . . . . . . . . . . . . . . . . 26 119 6.1.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . 27 120 6.2. Client Commands - Not Authenticated State . . . . . . . . 27 121 6.2.1. STARTTLS Command . . . . . . . . . . . . . . . . . . 28 122 6.2.2. AUTHENTICATE Command . . . . . . . . . . . . . . . . 29 123 6.2.3. LOGIN Command . . . . . . . . . . . . . . . . . . . . 32 124 6.3. Client Commands - Authenticated State . . . . . . . . . . 33 125 6.3.1. ENABLE Command . . . . . . . . . . . . . . . . . . . 33 126 6.3.2. SELECT Command . . . . . . . . . . . . . . . . . . . 35 127 6.3.3. EXAMINE Command . . . . . . . . . . . . . . . . . . . 37 128 6.3.4. CREATE Command . . . . . . . . . . . . . . . . . . . 38 129 6.3.5. DELETE Command . . . . . . . . . . . . . . . . . . . 39 130 6.3.6. RENAME Command . . . . . . . . . . . . . . . . . . . 41 131 6.3.7. SUBSCRIBE Command . . . . . . . . . . . . . . . . . . 43 132 6.3.8. UNSUBSCRIBE Command . . . . . . . . . . . . . . . . . 44 133 6.3.9. LIST Command . . . . . . . . . . . . . . . . . . . . 44 134 6.3.10. NAMESPACE Command . . . . . . . . . . . . . . . . . . 62 135 6.3.11. STATUS Command . . . . . . . . . . . . . . . . . . . 67 136 6.3.12. APPEND Command . . . . . . . . . . . . . . . . . . . 68 137 6.3.13. IDLE Command . . . . . . . . . . . . . . . . . . . . 71 138 6.4. Client Commands - Selected State . . . . . . . . . . . . 73 139 6.4.1. CLOSE Command . . . . . . . . . . . . . . . . . . . . 74 140 6.4.2. UNSELECT Command . . . . . . . . . . . . . . . . . . 74 141 6.4.3. EXPUNGE Command . . . . . . . . . . . . . . . . . . . 75 142 6.4.4. SEARCH Command . . . . . . . . . . . . . . . . . . . 75 143 6.4.5. FETCH Command . . . . . . . . . . . . . . . . . . . . 87 144 6.4.6. STORE Command . . . . . . . . . . . . . . . . . . . . 92 145 6.4.7. COPY Command . . . . . . . . . . . . . . . . . . . . 93 146 6.4.8. MOVE Command . . . . . . . . . . . . . . . . . . . . 94 147 6.4.9. UID Command . . . . . . . . . . . . . . . . . . . . . 96 148 6.5. Client Commands - Experimental/Expansion . . . . . . . . 97 149 6.5.1. X Command . . . . . . . . . . . . . . . . . . . 97 150 7. Server Responses . . . . . . . . . . . . . . . . . . . . . . 98 151 7.1. Server Responses - Status Responses . . . . . . . . . . . 99 152 7.1.1. OK Response . . . . . . . . . . . . . . . . . . . . . 107 153 7.1.2. NO Response . . . . . . . . . . . . . . . . . . . . . 108 154 7.1.3. BAD Response . . . . . . . . . . . . . . . . . . . . 108 155 7.1.4. PREAUTH Response . . . . . . . . . . . . . . . . . . 108 156 7.1.5. BYE Response . . . . . . . . . . . . . . . . . . . . 109 157 7.2. Server Responses - Server and Mailbox Status . . . . . . 109 158 7.2.1. The ENABLED Response . . . . . . . . . . . . . . . . 110 159 7.2.2. CAPABILITY Response . . . . . . . . . . . . . . . . . 110 160 7.2.3. LIST Response . . . . . . . . . . . . . . . . . . . . 111 161 7.2.4. NAMESPACE Response . . . . . . . . . . . . . . . . . 115 162 7.2.5. STATUS Response . . . . . . . . . . . . . . . . . . . 115 163 7.2.6. ESEARCH Response . . . . . . . . . . . . . . . . . . 115 164 7.2.7. FLAGS Response . . . . . . . . . . . . . . . . . . . 116 165 7.3. Server Responses - Mailbox Size . . . . . . . . . . . . . 116 166 7.3.1. EXISTS Response . . . . . . . . . . . . . . . . . . . 116 167 7.4. Server Responses - Message Status . . . . . . . . . . . . 117 168 7.4.1. EXPUNGE Response . . . . . . . . . . . . . . . . . . 117 169 7.4.2. FETCH Response . . . . . . . . . . . . . . . . . . . 118 170 7.5. Server Responses - Command Continuation Request . . . . . 124 171 8. Sample IMAP4rev2 connection . . . . . . . . . . . . . . . . . 124 172 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 125 173 10. Author's Note . . . . . . . . . . . . . . . . . . . . . . . . 143 174 11. Security Considerations . . . . . . . . . . . . . . . . . . . 143 175 11.1. STARTTLS Security Considerations . . . . . . . . . . . . 143 176 11.2. COPYUID and APPENDUID response codes . . . . . . . . . . 144 177 11.3. LIST command and Other Users' namespace . . . . . . . . 144 178 11.4. Other Security Considerations . . . . . . . . . . . . . 144 179 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 145 180 12.1. Updates to IMAP4 Capabilities registry . . . . . . . . . 146 181 12.2. GSSAPI/SASL service name . . . . . . . . . . . . . . . . 146 182 12.3. LIST Selection Options, LIST Return Options, LIST 183 extended data items . . . . . . . . . . . . . . . . . . 146 184 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 146 185 13.1. Normative References . . . . . . . . . . . . . . . . . . 146 186 13.2. Informative References (related protocols) . . . . . . . 150 187 13.3. Informative References (historical aspects of IMAP and 188 related protocols) . . . . . . . . . . . . . . . . . . . 152 189 Appendix A. Backward compatibility with IMAP4rev1 . . . . . . . 152 190 A.1. Mailbox International Naming Convention for compatibility 191 with IMAP4rev1 . . . . . . . . . . . . . . . . . . . . . 153 193 Appendix B. Backward compatibility with BINARY extension . . . . 154 194 Appendix C. Backward compatibility with LIST-EXTENDED extension 155 195 Appendix D. Changes from RFC 3501 / IMAP4rev1 . . . . . . . . . 155 196 Appendix E. Other Recommended IMAP Extensions . . . . . . . . . 156 197 Appendix F. Acknowledgement . . . . . . . . . . . . . . . . . . 157 198 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 199 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 163 201 1. How to Read This Document 203 1.1. Organization of This Document 205 This document is written from the point of view of the implementor of 206 an IMAP4rev2 client or server. Beyond the protocol overview in 207 section 2, it is not optimized for someone trying to understand the 208 operation of the protocol. The material in sections 3 through 5 209 provides the general context and definitions with which IMAP4rev2 210 operates. 212 Sections 6, 7, and 9 describe the IMAP commands, responses, and 213 syntax, respectively. The relationships among these are such that it 214 is almost impossible to understand any of them separately. In 215 particular, do not attempt to deduce command syntax from the command 216 section alone; instead refer to the Formal Syntax section. 218 1.2. Conventions Used in This Document 220 "Conventions" are basic principles or procedures. Document 221 conventions are noted in this section. 223 In examples, "C:" and "S:" indicate lines sent by the client and 224 server respectively. 226 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 227 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 228 "OPTIONAL" in this document are to be interpreted as described in BCP 229 14 [RFC2119] [RFC8174] when, and only when, they appear in all 230 capitals, as shown here. 232 The word "can" (not "may") is used to refer to a possible 233 circumstance or situation, as opposed to an optional facility of the 234 protocol. 236 "User" is used to refer to a human user, whereas "client" refers to 237 the software being run by the user. 239 "Connection" refers to the entire sequence of client/server 240 interaction from the initial establishment of the network connection 241 until its termination. 243 "Session" refers to the sequence of client/server interaction from 244 the time that a mailbox is selected (SELECT or EXAMINE command) until 245 the time that selection ends (SELECT or EXAMINE of another mailbox, 246 CLOSE command, UNSELECT command, or connection termination). 248 Characters are 8-bit UTF-8 (of which 7-bit US-ASCII is a subset) 249 unless otherwise specified. Other character sets are indicated using 250 a "CHARSET", as described in [MIME-IMT] and defined in [CHARSET]. 251 CHARSETs have important additional semantics in addition to defining 252 character set; refer to these documents for more detail. 254 There are several protocol conventions in IMAP. These refer to 255 aspects of the specification which are not strictly part of the IMAP 256 protocol, but reflect generally-accepted practice. Implementations 257 need to be aware of these conventions, and avoid conflicts whether or 258 not they implement the convention. For example, "&" may not be used 259 as a hierarchy delimiter since it conflicts with the Mailbox 260 International Naming Convention, and other uses of "&" in mailbox 261 names are impacted as well. 263 1.3. Special Notes to Implementors 265 Implementors of the IMAP protocol are strongly encouraged to read the 266 IMAP implementation recommendations document [IMAP-IMPLEMENTATION] in 267 conjunction with this document, to help understand the intricacies of 268 this protocol and how best to build an interoperable product. 270 IMAP4rev2 is designed to be upwards compatible from the [IMAP2] and 271 unpublished IMAP2bis protocols. IMAP4rev2 is largely compatible with 272 the IMAP4rev1 protocol described in RFC 3501 and the IMAP4 protocol 273 described in RFC 1730; the exception being in certain facilities 274 added in RFC 1730 and RFC 3501 that proved problematic and were 275 subsequently removed or replaced by better alternatives. In the 276 course of the evolution of IMAP4rev2, some aspects in the earlier 277 protocols have become obsolete. Obsolete commands, responses, and 278 data formats which an IMAP4rev2 implementation can encounter when 279 used with an earlier implementation are described in Appendix D, 280 Appendix A and [IMAP-OBSOLETE]. IMAP4rev2 compatibility with BINARY 281 and LIST-EXTENDED IMAP extensions are described in Appendix B and 282 Appendix C respectively. 284 Other compatibility issues with IMAP2bis, the most common variant of 285 the earlier protocol, are discussed in [IMAP-COMPAT]. A full 286 discussion of compatibility issues with rare (and presumed extinct) 287 variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is 288 primarily of historical interest. 290 IMAP was originally developed for the older [RFC-822] standard, and 291 as a consequence several fetch items in IMAP incorporate "RFC822" in 292 their name. In all cases, "RFC822" should be interpreted as a 293 reference to the updated [RFC-5322] standard. 295 2. Protocol Overview 297 2.1. Link Level 299 The IMAP4rev2 protocol assumes a reliable data stream such as that 300 provided by TCP. When TCP is used, an IMAP4rev2 server listens on 301 port 143 or port 993 (IMAP-over-TLS). 303 2.2. Commands and Responses 305 An IMAP4rev2 connection consists of the establishment of a client/ 306 server network connection, an initial greeting from the server, and 307 client/server interactions. These client/server interactions consist 308 of a client command, server data, and a server completion result 309 response. 311 All interactions transmitted by client and server are in the form of 312 lines, that is, strings that end with a CRLF. The protocol receiver 313 of an IMAP4rev2 client or server is either reading a line, or is 314 reading a sequence of octets with a known count followed by a line. 316 2.2.1. Client Protocol Sender and Server Protocol Receiver 318 The client command begins an operation. Each client command is 319 prefixed with an identifier (typically a short alphanumeric string, 320 e.g., A0001, A0002, etc.) called a "tag". A different tag is 321 generated by the client for each command. (More formally: the client 322 SHOULD generate a unique tag for every command, but a server MUST 323 accept tag reuse.) 325 Clients MUST follow the syntax outlined in this specification 326 strictly. It is a syntax error to send a command with missing or 327 extraneous spaces or arguments. 329 There are two cases in which a line from the client does not 330 represent a complete command. In one case, a command argument is 331 quoted with an octet count (see the description of literal in String 332 under Data Formats); in the other case, the command arguments require 333 server feedback (see the AUTHENTICATE command). In either case, the 334 server sends a command continuation request response if it is ready 335 for the octets (if appropriate) and the remainder of the command. 336 This response is prefixed with the token "+". 338 Note: If instead, the server detected an error in the command, it 339 sends a BAD completion response with a tag matching the command 340 (as described below) to reject the command and prevent the client 341 from sending any more of the command. 343 It is also possible for the server to send a completion response 344 for some other command (if multiple commands are in progress), or 345 untagged data. In either case, the command continuation request 346 is still pending; the client takes the appropriate action for the 347 response, and reads another response from the server. In all 348 cases, the client MUST send a complete command (including 349 receiving all command continuation request responses and command 350 continuations for the command) before initiating a new command. 352 The protocol receiver of an IMAP4rev2 server reads a command line 353 from the client, parses the command and its arguments, and transmits 354 server data and a server command completion result response. 356 2.2.2. Server Protocol Sender and Client Protocol Receiver 358 Data transmitted by the server to the client and status responses 359 that do not indicate command completion are prefixed with the token 360 "*", and are called untagged responses. 362 Server data MAY be sent as a result of a client command, or MAY be 363 sent unilaterally by the server. There is no syntactic difference 364 between server data that resulted from a specific command and server 365 data that were sent unilaterally. 367 The server completion result response indicates the success or 368 failure of the operation. It is tagged with the same tag as the 369 client command which began the operation. Thus, if more than one 370 command is in progress, the tag in a server completion response 371 identifies the command to which the response applies. There are 372 three possible server completion responses: OK (indicating success), 373 NO (indicating failure), or BAD (indicating a protocol error such as 374 unrecognized command or command syntax error). 376 Servers SHOULD enforce the syntax outlined in this specification 377 strictly. Any client command with a protocol syntax error, including 378 (but not limited to) missing or extraneous spaces or arguments, 379 SHOULD be rejected, and the client given a BAD server completion 380 response. 382 The protocol receiver of an IMAP4rev2 client reads a response line 383 from the server. It then takes action on the response based upon the 384 first token of the response, which can be a tag, a "*", or a "+". 386 A client MUST be prepared to accept any server response at all times. 387 This includes server data that was not requested. Server data SHOULD 388 be recorded, so that the client can reference its recorded copy 389 rather than sending a command to the server to request the data. In 390 the case of certain server data, the data MUST be recorded. 392 This topic is discussed in greater detail in the Server Responses 393 section. 395 2.3. Message Attributes 397 In addition to message text, each message has several attributes 398 associated with it. These attributes can be retrieved individually 399 or in conjunction with other attributes or message texts. 401 2.3.1. Message Numbers 403 Messages in IMAP4rev2 are accessed by one of two numbers; the unique 404 identifier or the message sequence number. 406 2.3.1.1. Unique Identifier (UID) Message Attribute 408 An unsigned non-zero 32-bit value assigned to each message, which 409 when used with the unique identifier validity value (see below) forms 410 a 64-bit value that MUST NOT refer to any other message in the 411 mailbox or any subsequent mailbox with the same name forever. Unique 412 identifiers are assigned in a strictly ascending fashion in the 413 mailbox; as each message is added to the mailbox it is assigned a 414 higher UID than the message(s) which were added previously. Unlike 415 message sequence numbers, unique identifiers are not necessarily 416 contiguous. 418 The unique identifier of a message MUST NOT change during the 419 session, and SHOULD NOT change between sessions. Any change of 420 unique identifiers between sessions MUST be detectable using the 421 UIDVALIDITY mechanism discussed below. Persistent unique identifiers 422 are required for a client to resynchronize its state from a previous 423 session with the server (e.g., disconnected or offline access clients 424 [IMAP-MODEL]); this is discussed further in [IMAP-DISC]. 426 Associated with every mailbox are two 32-bit unsigned non-zero values 427 which aid in unique identifier handling: the next unique identifier 428 value (UIDNEXT) and the unique identifier validity value 429 (UIDVALIDITY). 431 The next unique identifier value is the predicted value that will be 432 assigned to a new message in the mailbox. Unless the unique 433 identifier validity also changes (see below), the next unique 434 identifier value MUST have the following two characteristics. First, 435 the next unique identifier value MUST NOT change unless new messages 436 are added to the mailbox; and second, the next unique identifier 437 value MUST change whenever new messages are added to the mailbox, 438 even if those new messages are subsequently expunged. 440 Note: The next unique identifier value is intended to provide a 441 means for a client to determine whether any messages have been 442 delivered to the mailbox since the previous time it checked this 443 value. It is not intended to provide any guarantee that any 444 message will have this unique identifier. A client can only 445 assume, at the time that it obtains the next unique identifier 446 value, that messages arriving after that time will have a UID 447 greater than or equal to that value. 449 The unique identifier validity value is sent in a UIDVALIDITY 450 response code in an OK untagged response at mailbox selection time. 451 If unique identifiers from an earlier session fail to persist in this 452 session, the unique identifier validity value MUST be greater than 453 the one used in the earlier session. A good UIDVALIDITY value to use 454 is a 32-bit representation of the current date/time when the value is 455 assigned: this ensures that the value is unique and always increases. 456 Another possible alternative is a global counter that gets 457 incremented every time a mailbox is created. 459 Note: Ideally, unique identifiers SHOULD persist at all times. 460 Although this specification recognizes that failure to persist can 461 be unavoidable in certain server environments, it STRONGLY 462 ENCOURAGES message store implementation techniques that avoid this 463 problem. For example: 465 1. Unique identifiers MUST be strictly ascending in the mailbox 466 at all times. If the physical message store is re-ordered by 467 a non-IMAP agent, this requires that the unique identifiers in 468 the mailbox be regenerated, since the former unique 469 identifiers are no longer strictly ascending as a result of 470 the re-ordering. 472 2. If the message store has no mechanism to store unique 473 identifiers, it must regenerate unique identifiers at each 474 session, and each session must have a unique UIDVALIDITY 475 value. 477 3. If the mailbox is deleted/renamed and a new mailbox with the 478 same name is created at a later date, the server must either 479 keep track of unique identifiers from the previous instance of 480 the mailbox, or it must assign a new UIDVALIDITY value to the 481 new instance of the mailbox. 483 4. The combination of mailbox name, UIDVALIDITY, and UID must 484 refer to a single immutable (or expunged) message on that 485 server forever. In particular, the internal date, [RFC-5322] 486 size, envelope, body structure, and message texts (all 487 BODY[...] fetch data items) must never change. This does not 488 include message numbers, nor does it include attributes that 489 can be set by a STORE command (e.g., FLAGS). When a message 490 is expunged, its UID MUST NOT be reused under the same 491 UIDVALIDITY value. 493 2.3.1.2. Message Sequence Number Message Attribute 495 A relative position from 1 to the number of messages in the mailbox. 496 This position MUST be ordered by ascending unique identifier. As 497 each new message is added, it is assigned a message sequence number 498 that is 1 higher than the number of messages in the mailbox before 499 that new message was added. 501 Message sequence numbers can be reassigned during the session. For 502 example, when a message is permanently removed (expunged) from the 503 mailbox, the message sequence number for all subsequent messages is 504 decremented. The number of messages in the mailbox is also 505 decremented. Similarly, a new message can be assigned a message 506 sequence number that was once held by some other message prior to an 507 expunge. 509 In addition to accessing messages by relative position in the 510 mailbox, message sequence numbers can be used in mathematical 511 calculations. For example, if an untagged "11 EXISTS" is received, 512 and previously an untagged "8 EXISTS" was received, three new 513 messages have arrived with message sequence numbers of 9, 10, and 11. 514 Another example, if message 287 in a 523 message mailbox has UID 515 12345, there are exactly 286 messages which have lesser UIDs and 236 516 messages which have greater UIDs. 518 2.3.2. Flags Message Attribute 520 A list of zero or more named tokens associated with the message. A 521 flag is set by its addition to this list, and is cleared by its 522 removal. There are two types of flags in IMAP4rev2. A flag of 523 either type can be permanent or session-only. 525 A system flag is a flag name that is pre-defined in this 526 specification and begin with "\". Certain system flags (\Deleted and 527 \Seen) have special semantics described elsewhere in this document. 528 The currently-defined system flags are: 530 \Seen Message has been read 532 \Answered Message has been answered 534 \Flagged Message is "flagged" for urgent/special attention 536 \Deleted Message is "deleted" for removal by later EXPUNGE 538 \Draft Message has not completed composition (marked as a draft). 540 \Recent This flag was in used in IMAP4rev1 and is now deprecated. 542 A keyword is defined by the server implementation. Keywords do not 543 begin with "\". Servers MAY permit the client to define new keywords 544 in the mailbox (see the description of the PERMANENTFLAGS response 545 code for more information). Some keywords that start with "$" are 546 also defined in this specification. 548 This document defines several keywords that were not originally 549 defined in RFC 3501, but which were found to be useful by client 550 implementations. These keywords SHOULD be supported (i.e. allowed in 551 SEARCH, allowed and preserved in APPEND, COPY, MOVE commands) by 552 server implementations: 554 $Forwarded Message has been forwarded to another email address, 555 embedded within or attached to a new message. An email client 556 sets this keyword when it successfully forwards the message to 557 another email address. Typical usage of this keyword is to show a 558 different (or additional) icon for a message that has been 559 forwarded. Once set, the flag SHOULD NOT be cleared. 561 $MDNSent Message Disposition Notification [RFC8098] was generated 562 and sent for this message. See [RFC3503] for more details on how 563 this keyword is used. 565 $Junk The user (or a delivery agent on behalf of the user) may 566 choose to mark a message as definitely containing junk ($Junk; see 567 also the related keyword $NotJunk). The $Junk keyword can be used 568 to mark (and potentially move/delete messages later), group or 569 hide undesirable messages. See [IMAP-KEYWORDS-REG] for more 570 information. 572 $NotJunk The user (or a delivery agent on behalf of the user) may 573 choose to mark a message as definitely not containing junk 574 ($NotJunk; see also the related keyword $Junk). The $NotJunk 575 keyword can be used to mark, group or show messages that the user 576 wants to see. See [IMAP-KEYWORDS-REG] for more information. 578 $Phishing The $Phishing keyword can be used by a delivery agent to 579 mark a message as highly likely to be a phishing email. An email 580 that's determined to be a phishing email by the delivery agent 581 should also be considered a junk email and have the appropriate 582 junk filtering applied, including setting the $Junk flag and 583 placing in the \Junk special-use mailbox (see Section 7.2.3) if 584 available. 585 If both the $Phishing flag and the $Junk flag are set, the user 586 agent should display an additional warning message to the user. 587 User agents should not use the term "phishing" in their warning 588 message as most users do not understand this term. Phrasing of 589 the form "this message may be trying to steal your personal 590 information" is recommended. Additionally the user agent may 591 display a warning when clicking on any hyperlinks within the 592 message. 593 The requirement for both $Phishing and $Junk to be set before a 594 user agent displays a warning is for better backwards 595 compatibility with existing clients that understand the $Junk flag 596 but not the $Phishing flag. This so that when an unextended 597 client removes the $Junk flag, an extended client will also show 598 the correct state. See [IMAP-KEYWORDS-REG] for more information. 600 $Junk and $NotJunk are mutually exclusive. If more than one of them 601 is set for a message, the client MUST treat this as if none of them 602 is set and SHOULD unset both of them on the IMAP server. 604 Other registered keywords can be found in the "IMAP and JMAP 605 Keywords" registry [IMAP-KEYWORDS-REG]. New keywords SHOULD be 606 registered in this registry using the procedure specified in 607 [RFC5788]. 609 A flag can be permanent or session-only on a per-flag basis. 610 Permanent flags are those which the client can add or remove from the 611 message flags permanently; that is, concurrent and subsequent 612 sessions will see any change in permanent flags. Changes to session 613 flags are valid only in that session. 615 2.3.3. Internal Date Message Attribute 617 The internal date and time of the message on the server. This is not 618 the date and time in the [RFC-5322] header, but rather a date and 619 time which reflects when the message was received. In the case of 620 messages delivered via [SMTP], this SHOULD be the date and time of 621 final delivery of the message as defined by [SMTP]. In the case of 622 messages delivered by the IMAP4rev2 COPY or MOVE command, this SHOULD 623 be the internal date and time of the source message. In the case of 624 messages delivered by the IMAP4rev2 APPEND command, this SHOULD be 625 the date and time as specified in the APPEND command description. 626 All other cases are implementation defined. 628 2.3.4. [RFC-5322] Size Message Attribute 630 The number of octets in the message, as expressed in [RFC-5322] 631 format. 633 2.3.5. Envelope Structure Message Attribute 635 A parsed representation of the [RFC-5322] header of the message. 636 Note that the IMAP Envelope structure is not the same as an [SMTP] 637 envelope. 639 2.3.6. Body Structure Message Attribute 641 A parsed representation of the [MIME-IMB] body structure information 642 of the message. 644 2.4. Message Texts 646 In addition to being able to fetch the full [RFC-5322] text of a 647 message, IMAP4rev2 permits the fetching of portions of the full 648 message text. Specifically, it is possible to fetch the [RFC-5322] 649 message header, [RFC-5322] message body, a [MIME-IMB] body part, or a 650 [MIME-IMB] header. 652 3. State and Flow Diagram 654 Once the connection between client and server is established, an 655 IMAP4rev2 connection is in one of four states. The initial state is 656 identified in the server greeting. Most commands are only valid in 657 certain states. It is a protocol error for the client to attempt a 658 command while the connection is in an inappropriate state, and the 659 server will respond with a BAD or NO (depending upon server 660 implementation) command completion result. 662 3.1. Not Authenticated State 664 In the not authenticated state, the client MUST supply authentication 665 credentials before most commands will be permitted. This state is 666 entered when a connection starts unless the connection has been pre- 667 authenticated. 669 3.2. Authenticated State 671 In the authenticated state, the client is authenticated and MUST 672 select a mailbox to access before commands that affect messages will 673 be permitted. This state is entered when a pre-authenticated 674 connection starts, when acceptable authentication credentials have 675 been provided, after an error in selecting a mailbox, or after a 676 successful CLOSE command. 678 3.3. Selected State 680 In a selected state, a mailbox has been selected to access. This 681 state is entered when a mailbox has been successfully selected. 683 3.4. Logout State 685 In the logout state, the connection is being terminated. This state 686 can be entered as a result of a client request (via the LOGOUT 687 command) or by unilateral action on the part of either the client or 688 server. 690 If the client requests the logout state, the server MUST send an 691 untagged BYE response and a tagged OK response to the LOGOUT command 692 before the server closes the connection; and the client MUST read the 693 tagged OK response to the LOGOUT command before the client closes the 694 connection. 696 A server SHOULD NOT unilaterally close the connection without sending 697 an untagged BYE response that contains the reason for having done so. 698 A client SHOULD NOT unilaterally close the connection, and instead 699 SHOULD issue a LOGOUT command. If the server detects that the client 700 has unilaterally closed the connection, the server MAY omit the 701 untagged BYE response and simply close its connection. 703 +----------------------+ 704 |connection established| 705 +----------------------+ 706 || 707 \/ 708 +--------------------------------------+ 709 | server greeting | 710 +--------------------------------------+ 711 || (1) || (2) || (3) 712 \/ || || 713 +-----------------+ || || 714 |Not Authenticated| || || 715 +-----------------+ || || 716 || (7) || (4) || || 717 || \/ \/ || 718 || +----------------+ || 719 || | Authenticated |<=++ || 720 || +----------------+ || || 721 || || (7) || (5) || (6) || 722 || || \/ || || 723 || || +--------+ || || 724 || || |Selected|==++ || 725 || || +--------+ || 726 || || || (7) || 727 \/ \/ \/ \/ 728 +--------------------------------------+ 729 | Logout | 730 +--------------------------------------+ 731 || 732 \/ 733 +-------------------------------+ 734 |both sides close the connection| 735 +-------------------------------+ 737 (1) connection without pre-authentication (OK greeting) 738 (2) pre-authenticated connection (PREAUTH greeting) 739 (3) rejected connection (BYE greeting) 740 (4) successful LOGIN or AUTHENTICATE command 741 (5) successful SELECT or EXAMINE command 742 (6) CLOSE command, unsolicited CLOSED response code or 743 failed SELECT or EXAMINE command 744 (7) LOGOUT command, server shutdown, or connection closed 746 4. Data Formats 748 IMAP4rev2 uses textual commands and responses. Data in IMAP4rev2 can 749 be in one of several forms: atom, number, string, parenthesized list, 750 or NIL. Note that a particular data item may take more than one 751 form; for example, a data item defined as using "astring" syntax may 752 be either an atom or a string. 754 4.1. Atom 756 An atom consists of one or more non-special characters. 758 4.1.1. Sequence set and UID set 760 A set of messages can be referenced by a sequence set containing 761 either message sequence numbers or unique identifiers. See Section 9 762 for details. Sequence sets can contain ranges (e.g. "5:50"), an 763 enumeration of specific message/UID numbers, a special symbol "*", or 764 a combination of the above. 766 A "UID set" is similar to the sequence set of unique identifiers; 767 however, the "*" value for a sequence number is not permitted. 769 4.2. Number 771 A number consists of one or more digit characters, and represents a 772 numeric value. 774 4.3. String 776 A string is in one of three forms: synchonizing literal, non- 777 synchronizing literal or quoted string. The synchronizing literal 778 form is the general form of string. The non-synchronizing literal 779 form is also the general form, but has length limitation. The quoted 780 string form is an alternative that avoids the overhead of processing 781 a literal at the cost of limitations of characters which may be used. 783 When the distinction between synchronizing and non-synchronizing 784 literals is not important, this document just uses the term 785 "literal". 787 A synchronizing literal is a sequence of zero or more octets 788 (including CR and LF), prefix-quoted with an octet count in the form 789 of an open brace ("{"), the number of octets, close brace ("}"), and 790 CRLF. In the case of synchronizing literals transmitted from server 791 to client, the CRLF is immediately followed by the octet data. In 792 the case of synchronizing literals transmitted from client to server, 793 the client MUST wait to receive a command continuation request 794 (described later in this document) before sending the octet data (and 795 the remainder of the command). 797 The non-synchronizing literal is an alternate form of synchronizing 798 literal, and it may appear in communication from client to server 799 instead of the synchonizing form of literal. The non-synchronizing 800 literal form MUST NOT be sent from server to client. The non- 801 synchronizing literal is distinguished from the synchronizing literal 802 by having a plus ("+") between the octet count and the closing brace 803 ("}"). The server does not generate a command continuation request 804 in response to a non-synchronizing literal, and clients are not 805 required to wait before sending the octets of a non- synchronizing 806 literal. Non-synchronizing literals MUST NOT be larger than 4096 807 octets. Any literal larger than 4096 bytes MUST be sent as a 808 synchronizing literal. (Non-synchronizing literals defined in this 809 document are the same as non-synchronizing literals defined by the 810 LITERAL- extension from [RFC7888]. See that document for details on 811 how to handle invalid non-synchronizing literals longer than 4096 812 octets and for interaction with other IMAP extensions.) 814 A quoted string is a sequence of zero or more Unicode characters, 815 excluding CR and LF, encoded in UTF-8, with double quote (<">) 816 characters at each end. 818 The empty string is represented as "" (a quoted string with zero 819 characters between double quotes), as {0} followed by CRLF (a 820 synchronizing literal with an octet count of 0) or as {0+} followed 821 by CRLF (a non-synchronizing literal with an octet count of 0). 823 Note: Even if the octet count is 0, a client transmitting a 824 synchronizing literal MUST wait to receive a command continuation 825 request. 827 4.3.1. 8-bit and Binary Strings 829 8-bit textual and binary mail is supported through the use of a 830 [MIME-IMB] content transfer encoding. IMAP4rev2 implementations MAY 831 transmit 8-bit or multi-octet characters in literals, but SHOULD do 832 so only when the [CHARSET] is identified. 834 IMAP4rev2 is compatible with [I18N-HDRS]. As a result, the 835 identified charset for header-field values with 8-bit content is 836 UTF-8 [UTF-8]. IMAP4rev2 implementations MUST accept and MAY 837 transmit [UTF-8] text in quoted-strings as long as the string does 838 not contain NUL, CR, or LF. This differs from IMAP4rev1 839 implementations. 841 Although a BINARY content transfer encoding is defined, unencoded 842 binary strings are not permitted, unless returned in a in 843 response to BINARY.PEEK[]<> or 844 BINARY[]<> FETCH data item. A "binary 845 string" is any string with NUL characters. A string with an 846 excessive amount of CTL characters MAY also be considered to be 847 binary. Unless returned in response to BINARY.PEEK[...]/BINARY[...] 848 FETCH, client and server implementations MUST encode binary data into 849 a textual form, such as BASE64, before transmitting the data. 851 4.4. Parenthesized List 853 Data structures are represented as a "parenthesized list"; a sequence 854 of data items, delimited by space, and bounded at each end by 855 parentheses. A parenthesized list can contain other parenthesized 856 lists, using multiple levels of parentheses to indicate nesting. 858 The empty list is represented as () -- a parenthesized list with no 859 members. 861 4.5. NIL 863 The special form "NIL" represents the non-existence of a particular 864 data item that is represented as a string or parenthesized list, as 865 distinct from the empty string "" or the empty parenthesized list (). 867 Note: NIL is never used for any data item which takes the form of 868 an atom. For example, a mailbox name of "NIL" is a mailbox named 869 NIL as opposed to a non-existent mailbox name. This is because 870 mailbox uses "astring" syntax which is an atom or a string. 871 Conversely, an addr-name of NIL is a non-existent personal name, 872 because addr-name uses "nstring" syntax which is NIL or a string, 873 but never an atom. 875 Examples: 877 The following LIST response: 879 * LIST () "/" NIL 881 is equivalent to: 882 * LIST () "/" "NIL" 884 as LIST response ABNF is using astring for mailbox name. 886 However, the following response 888 * FETCH 1 (BODY[1] NIL) 890 is not equivalent to: 891 * FETCH 1 (BODY[1] "NIL") 892 The former means absence of the body part, while the latter 893 means that it contains literal sequence of characters "NIL". 895 5. Operational Considerations 897 The following rules are listed here to ensure that all IMAP4rev2 898 implementations interoperate properly. 900 5.1. Mailbox Naming 902 In IMAP4rev2, Mailbox names are encoded in Net-Unicode [NET-UNICODE] 903 (this differs from IMAP4rev1). Client implementations MAY attempt to 904 create Net-Unicode mailbox names, and MUST interpret any 8-bit 905 mailbox names returned by LIST as [NET-UNICODE]. Server 906 implementations MUST prohibit the creation of 8-bit mailbox names 907 that do not comply with Net-Unicode. However, servers MAY accept a 908 de-normalized UTF-8 mailbox name and convert it to Unicode 909 normalization form "NFC" (as per Net-Unicode requirements) prior to 910 mailbox creation. Servers that choose to accept such de-normalized 911 UTF-8 mailbox names MUST accept them in all IMAP commands that have a 912 mailbox name parameter. In particular SELECT must open the 913 same mailbox that was successfully created with CREATE , even 914 if is a de-normalized UTF-8 mailbox name. 916 The case-insensitive mailbox name INBOX is a special name reserved to 917 mean "the primary mailbox for this user on this server". (Note that 918 this special name may not exist on some servers for some users, for 919 example if the user has no access to personal namespace.) The 920 interpretation of all other names is implementation-dependent. 922 In particular, this specification takes no position on case 923 sensitivity in non-INBOX mailbox names. Some server implementations 924 are fully case-sensitive in ASCII range; others preserve case of a 925 newly-created name but otherwise are case-insensitive; and yet others 926 coerce names to a particular case. Client implementations must be 927 able to interact with any of these. 929 There are certain client considerations when creating a new mailbox 930 name: 932 1. Any character which is one of the atom-specials (see the Formal 933 Syntax) will require that the mailbox name be represented as a 934 quoted string or literal. 936 2. CTL and other non-graphic characters are difficult to represent 937 in a user interface and are best avoided. Servers MAY refuse to 938 create mailbox names containing Unicode CTL characters. 940 3. Although the list-wildcard characters ("%" and "*") are valid in 941 a mailbox name, it is difficult to use such mailbox names with 942 the LIST command due to the conflict with wildcard 943 interpretation. 945 4. Usually, a character (determined by the server implementation) is 946 reserved to delimit levels of hierarchy. 948 5. Two characters, "#" and "&", have meanings by convention, and 949 should be avoided except when used in that convention. See 950 Section 5.1.2.1 and Appendix A.1 respectively. 952 5.1.1. Mailbox Hierarchy Naming 954 If it is desired to export hierarchical mailbox names, mailbox names 955 MUST be left-to-right hierarchical using a single character to 956 separate levels of hierarchy. The same hierarchy separator character 957 is used for all levels of hierarchy within a single name. 959 5.1.2. Namespaces 961 Personal Namespace: A namespace that the server considers within the 962 personal scope of the authenticated user on a particular connection. 963 Typically, only the authenticated user has access to mailboxes in 964 their Personal Namespace. It is the part of the namespace that 965 belongs to the user that is allocated for mailboxes. If an INBOX 966 exists for a user, it MUST appear within the user's personal 967 namespace. In the typical case, there SHOULD be only one Personal 968 Namespace on a server. 970 Other Users' Namespace: A namespace that consists of mailboxes from 971 the Personal Namespaces of other users. To access mailboxes in the 972 Other Users' Namespace, the currently authenticated user MUST be 973 explicitly granted access rights. For example, it is common for a 974 manager to grant to their secretary access rights to their mailbox. 975 In the typical case, there SHOULD be only one Other Users' Namespace 976 on a server. 978 Shared Namespace: A namespace that consists of mailboxes that are 979 intended to be shared amongst users and do not exist within a user's 980 Personal Namespace. 982 The namespaces a server uses MAY differ on a per-user basis. 984 5.1.2.1. Historic Mailbox Namespace Naming Convention 986 By convention, the first hierarchical element of any mailbox name 987 which begins with "#" identifies the "namespace" of the remainder of 988 the name. This makes it possible to disambiguate between different 989 types of mailbox stores, each of which have their own namespaces. 991 For example, implementations which offer access to USENET 992 newsgroups MAY use the "#news" namespace to partition the USENET 993 newsgroup namespace from that of other mailboxes. Thus, the 994 comp.mail.misc newsgroup would have a mailbox name of 995 "#news.comp.mail.misc", and the name "comp.mail.misc" can refer to 996 a different object (e.g., a user's private mailbox). 998 Namespaces that include the "#" character are not IMAP URL [IMAP-URL] 999 friendly requiring the "#" character to be represented as %23 when 1000 within URLs. As such, server implementers MAY instead consider using 1001 namespace prefixes that do not contain the "#" character. 1003 5.1.2.2. Common namespace models 1005 Previous version of this protocol does not define a default server 1006 namespace. Two common namespace models have evolved: 1008 The "Personal Mailbox" model, in which the default namespace that is 1009 presented consists of only the user's personal mailboxes. To access 1010 shared mailboxes, the user must use an escape mechanism to reach 1011 another namespace. 1013 The "Complete Hierarchy" model, in which the default namespace that 1014 is presented includes the user's personal mailboxes along with any 1015 other mailboxes they have access to. 1017 5.2. Mailbox Size and Message Status Updates 1019 At any time, a server can send data that the client did not request. 1020 Sometimes, such behavior is REQUIRED. For example, agents other than 1021 the server MAY add messages to the mailbox (e.g., new message 1022 delivery), change the flags of the messages in the mailbox (e.g., 1023 simultaneous access to the same mailbox by multiple agents), or even 1024 remove messages from the mailbox. A server MUST send mailbox size 1025 updates automatically if a mailbox size change is observed during the 1026 processing of a command. A server SHOULD send message flag updates 1027 automatically, without requiring the client to request such updates 1028 explicitly. 1030 Special rules exist for server notification of a client about the 1031 removal of messages to prevent synchronization errors; see the 1032 description of the EXPUNGE response for more detail. In particular, 1033 it is NOT permitted to send an EXISTS response that would reduce the 1034 number of messages in the mailbox; only the EXPUNGE response can do 1035 this. 1037 Regardless of what implementation decisions a client makes on 1038 remembering data from the server, a client implementation MUST record 1039 mailbox size updates. It MUST NOT assume that any command after the 1040 initial mailbox selection will return the size of the mailbox. 1042 5.3. Response when no Command in Progress 1044 Server implementations are permitted to send an untagged response 1045 (except for EXPUNGE) while there is no command in progress. Server 1046 implementations that send such responses MUST deal with flow control 1047 considerations. Specifically, they MUST either (1) verify that the 1048 size of the data does not exceed the underlying transport's available 1049 window size, or (2) use non-blocking writes. 1051 5.4. Autologout Timer 1053 If a server has an inactivity autologout timer that applies to 1054 sessions after authentication, the duration of that timer MUST be at 1055 least 30 minutes. The receipt of ANY command from the client during 1056 that interval SHOULD suffice to reset the autologout timer. 1058 5.5. Multiple Commands in Progress (Command Pipelining) 1060 The client MAY send another command without waiting for the 1061 completion result response of a command, subject to ambiguity rules 1062 (see below) and flow control constraints on the underlying data 1063 stream. Similarly, a server MAY begin processing another command 1064 before processing the current command to completion, subject to 1065 ambiguity rules. However, any command continuation request responses 1066 and command continuations MUST be negotiated before any subsequent 1067 command is initiated. 1069 The exception is if an ambiguity would result because of a command 1070 that would affect the results of other commands. If the server 1071 detects a possible ambiguity, it MUST execute commands to completion 1072 in the order given by the client. 1074 The most obvious example of ambiguity is when a command would affect 1075 the results of another command, e.g., a FETCH of a message's flags 1076 and a STORE of that same message's flags. 1078 A non-obvious ambiguity occurs with commands that permit an untagged 1079 EXPUNGE response (commands other than FETCH, STORE, and SEARCH), 1080 since an untagged EXPUNGE response can invalidate sequence numbers in 1081 a subsequent command. This is not a problem for FETCH, STORE, or 1082 SEARCH commands because servers are prohibited from sending EXPUNGE 1083 responses while any of those commands are in progress. Therefore, if 1084 the client sends any command other than FETCH, STORE, or SEARCH, it 1085 MUST wait for the completion result response before sending a command 1086 with message sequence numbers. 1088 Note: EXPUNGE responses are permitted while UID FETCH, UID STORE, 1089 and UID SEARCH are in progress. If the client sends a UID 1090 command, it MUST wait for a completion result response before 1091 sending a command which uses message sequence numbers (this may 1092 include UID SEARCH). Any message sequence numbers in an argument 1093 to UID SEARCH are associated with messages prior to the effect of 1094 any untagged EXPUNGE returned by the UID SEARCH. 1096 For example, the following non-waiting command sequences are invalid: 1098 FETCH + NOOP + STORE 1100 STORE + COPY + FETCH 1102 COPY + COPY 1104 The following are examples of valid non-waiting command sequences: 1106 FETCH + STORE + SEARCH + NOOP 1108 STORE + COPY + EXPUNGE 1110 UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting 1111 command sequence, depending upon whether or not the second UID 1112 SEARCH contains message sequence numbers. 1114 Use of SEARCH result variable (see Section 6.4.4.1) creates direct 1115 dependency between two commands. See Section 6.4.4.2 for more 1116 considerations about pipelining such dependent commands. 1118 6. Client Commands 1120 IMAP4rev2 commands are described in this section. Commands are 1121 organized by the state in which the command is permitted. Commands 1122 which are permitted in multiple states are listed in the minimum 1123 permitted state (for example, commands valid in authenticated and 1124 selected state are listed in the authenticated state commands). 1126 Command arguments, identified by "Arguments:" in the command 1127 descriptions below, are described by function, not by syntax. The 1128 precise syntax of command arguments is described in the Formal Syntax 1129 (Section 9). 1131 Some commands cause specific server responses to be returned; these 1132 are identified by "Responses:" in the command descriptions below. 1133 See the response descriptions in the Responses section for 1134 information on these responses, and the Formal Syntax section for the 1135 precise syntax of these responses. It is possible for server data to 1136 be transmitted as a result of any command. Thus, commands that do 1137 not specifically require server data specify "no specific responses 1138 for this command" instead of "none". 1140 The "Result:" in the command description refers to the possible 1141 tagged status responses to a command, and any special interpretation 1142 of these status responses. 1144 The state of a connection is only changed by successful commands 1145 which are documented as changing state. A rejected command (BAD 1146 response) never changes the state of the connection or of the 1147 selected mailbox. A failed command (NO response) generally does not 1148 change the state of the connection or of the selected mailbox; the 1149 exception being the SELECT and EXAMINE commands. 1151 6.1. Client Commands - Any State 1153 The following commands are valid in any state: CAPABILITY, NOOP, and 1154 LOGOUT. 1156 6.1.1. CAPABILITY Command 1158 Arguments: none 1160 Responses: REQUIRED untagged response: CAPABILITY 1161 Result: OK - capability completed 1162 BAD - command unknown or arguments invalid 1164 The CAPABILITY command requests a listing of capabilities that the 1165 server supports. The server MUST send a single untagged CAPABILITY 1166 response with "IMAP4rev2" as one of the listed capabilities before 1167 the (tagged) OK response. 1169 A capability name which begins with "AUTH=" indicates that the server 1170 supports that particular authentication mechanism. All such names 1171 are, by definition, part of this specification. For example, the 1172 authorization capability for an experimental "blurdybloop" 1173 authenticator would be "AUTH=XBLURDYBLOOP" and not 1174 "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP". 1176 Other capability names refer to extensions, revisions, or amendments 1177 to this specification. See the documentation of the CAPABILITY 1178 response for additional information. No capabilities, beyond the 1179 base IMAP4rev2 set defined in this specification, are enabled without 1180 explicit client action to invoke the capability. 1182 Client and server implementations MUST implement the STARTTLS, 1183 LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) capabilities. 1184 See the Security Considerations section for important information. 1186 See the section entitled "Client Commands - Experimental/Expansion" 1187 for information about the form of site or implementation-specific 1188 capabilities. 1190 Example: C: abcd CAPABILITY 1191 S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI 1192 LOGINDISABLED 1193 S: abcd OK CAPABILITY completed 1194 C: efgh STARTTLS 1195 S: efgh OK STARTLS completed 1196 1197 C: ijkl CAPABILITY 1198 S: * CAPABILITY IMAP4rev2 AUTH=GSSAPI AUTH=PLAIN 1199 S: ijkl OK CAPABILITY completed 1201 6.1.2. NOOP Command 1203 Arguments: none 1205 Responses: no specific responses for this command (but see below) 1207 Result: OK - noop completed 1208 BAD - command unknown or arguments invalid 1210 The NOOP command always succeeds. It does nothing. 1212 Since any command can return a status update as untagged data, the 1213 NOOP command can be used as a periodic poll for new messages or 1214 message status updates during a period of inactivity (the IDLE 1215 command Section 6.3.13 should be used instead of NOOP if real-time 1216 updates to mailbox state are desirable). The NOOP command can also 1217 be used to reset any inactivity autologout timer on the server. 1219 Example: C: a002 NOOP 1220 S: a002 OK NOOP completed 1221 . . . 1222 C: a047 NOOP 1223 S: * 22 EXPUNGE 1224 S: * 23 EXISTS 1225 S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted)) 1226 S: a047 OK NOOP completed 1228 6.1.3. LOGOUT Command 1230 Arguments: none 1232 Responses: REQUIRED untagged response: BYE 1234 Result: OK - logout completed 1235 BAD - command unknown or arguments invalid 1237 The LOGOUT command informs the server that the client is done with 1238 the connection. The server MUST send a BYE untagged response before 1239 the (tagged) OK response, and then close the network connection. 1241 Example: C: A023 LOGOUT 1242 S: * BYE IMAP4rev2 Server logging out 1243 S: A023 OK LOGOUT completed 1244 (Server and client then close the connection) 1246 6.2. Client Commands - Not Authenticated State 1248 In the not authenticated state, the AUTHENTICATE or LOGIN command 1249 establishes authentication and enters the authenticated state. The 1250 AUTHENTICATE command provides a general mechanism for a variety of 1251 authentication techniques, privacy protection, and integrity 1252 checking; whereas the LOGIN command uses a traditional user name and 1253 plaintext password pair and has no means of establishing privacy 1254 protection or integrity checking. 1256 The STARTTLS command is an alternate form of establishing session 1257 privacy protection and integrity checking, but does not by itself 1258 establish authentication or enter the authenticated state. 1260 Server implementations MAY allow access to certain mailboxes without 1261 establishing authentication. This can be done by means of the 1262 ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older 1263 convention is a LOGIN command using the userid "anonymous"; in this 1264 case, a password is required although the server may choose to accept 1265 any password. The restrictions placed on anonymous users are 1266 implementation-dependent. 1268 Once authenticated (including as anonymous), it is not possible to 1269 re-enter not authenticated state. 1271 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1272 the following commands are valid in the not authenticated state: 1273 STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations 1274 section for important information about these commands. 1276 6.2.1. STARTTLS Command 1278 Arguments: none 1280 Responses: no specific response for this command 1282 Result: OK - starttls completed, begin TLS negotiation 1283 BAD - STARTTLS received after a successful TLS 1284 negotiation or arguments invalid 1286 A TLS [TLS-1.3] negotiation begins immediately after the CRLF at the 1287 end of the tagged OK response from the server. Once a client issues 1288 a STARTTLS command, it MUST NOT issue further commands until a server 1289 response is seen and the TLS negotiation is complete. 1291 The server remains in the non-authenticated state, even if client 1292 credentials are supplied during the TLS negotiation. This does not 1293 preclude an authentication mechanism such as EXTERNAL (defined in 1294 [SASL]) from using client identity determined by the TLS negotiation. 1296 Once TLS has been started, the client MUST discard cached information 1297 about server capabilities and SHOULD re-issue the CAPABILITY command. 1298 This is necessary to protect against man-in- the-middle attacks which 1299 alter the capabilities list prior to STARTTLS. The server MAY 1300 advertise different capabilities, and in particular SHOULD NOT 1301 advertise the STARTTLS capability, after a successful STARTTLS 1302 command. 1304 Example: C: a001 CAPABILITY 1305 S: * CAPABILITY IMAP4rev2 STARTTLS LOGINDISABLED 1306 S: a001 OK CAPABILITY completed 1307 C: a002 STARTTLS 1308 S: a002 OK Begin TLS negotiation now 1309 1310 C: a003 CAPABILITY 1311 S: * CAPABILITY IMAP4rev2 AUTH=PLAIN 1312 S: a003 OK CAPABILITY completed 1313 C: a004 LOGIN joe password 1314 S: a004 OK LOGIN completed 1316 6.2.2. AUTHENTICATE Command 1318 Arguments: SASL authentication mechanism name 1319 OPTIONAL initial response 1321 Responses: continuation data can be requested 1323 Result: OK - authenticate completed, now in authenticated state 1324 NO - authenticate failure: unsupported authentication 1325 mechanism, credentials rejected 1326 BAD - command unknown or arguments invalid, 1327 authentication exchange cancelled 1329 The AUTHENTICATE command indicates a [SASL] authentication mechanism 1330 to the server. If the server supports the requested authentication 1331 mechanism, it performs an authentication protocol exchange to 1332 authenticate and identify the client. It MAY also negotiate an 1333 OPTIONAL security layer for subsequent protocol interactions. If the 1334 requested authentication mechanism is not supported, the server 1335 SHOULD reject the AUTHENTICATE command by sending a tagged NO 1336 response. 1338 The AUTHENTICATE command supports the optional "initial response" 1339 feature defined in Section 5.1 of [SASL]. The client doesn't need to 1340 use it. If a SASL mechanism supports "initial response", but it is 1341 not specified by the client, the server handles this as specified in 1342 Section 3 of [SASL]. 1344 The service name specified by this protocol's profile of [SASL] is 1345 "imap". 1347 The authentication protocol exchange consists of a series of server 1348 challenges and client responses that are specific to the 1349 authentication mechanism. A server challenge consists of a command 1350 continuation request response with the "+" token followed by a BASE64 1351 encoded (see Section 4 of [RFC4648]) string. The client response 1352 consists of a single line consisting of a BASE64 encoded string. If 1353 the client wishes to cancel an authentication exchange, it issues a 1354 line consisting of a single "*". If the server receives such a 1355 response, or if it receives an invalid BASE64 string (e.g. 1356 characters outside the BASE64 alphabet, or non-terminal "="), it MUST 1357 reject the AUTHENTICATE command by sending a tagged BAD response. 1359 As with any other client response, this initial response MUST be 1360 encoded as BASE64. It also MUST be transmitted outside of a quoted 1361 string or literal. To send a zero-length initial response, the 1362 client MUST send a single pad character ("="). This indicates that 1363 the response is present, but is a zero-length string. 1365 When decoding the BASE64 data in the initial response, decoding 1366 errors MUST be treated as in any normal SASL client response, i.e. 1367 with a tagged BAD response. In particular, the server should check 1368 for any characters not explicitly allowed by the BASE64 alphabet, as 1369 well as any sequence of BASE64 characters that contains the pad 1370 character ('=') anywhere other than the end of the string (e.g., 1371 "=AAA" and "AAA=BBB" are not allowed). 1373 If the client uses an initial response with a SASL mechanism that 1374 does not support an initial response, the server MUST reject the 1375 command with a tagged BAD response. 1377 If a security layer is negotiated through the [SASL] authentication 1378 exchange, it takes effect immediately following the CRLF that 1379 concludes the authentication exchange for the client, and the CRLF of 1380 the tagged OK response for the server. 1382 While client and server implementations MUST implement the 1383 AUTHENTICATE command itself, it is not required to implement any 1384 authentication mechanisms other than the PLAIN mechanism described in 1385 [PLAIN]. Also, an authentication mechanism is not required to 1386 support any security layers. 1388 Note: a server implementation MUST implement a configuration in 1389 which it does NOT permit any plaintext password mechanisms, unless 1390 either the STARTTLS command has been negotiated or some other 1391 mechanism that protects the session from password snooping has 1392 been provided. Server sites SHOULD NOT use any configuration 1393 which permits a plaintext password mechanism without such a 1394 protection mechanism against password snooping. Client and server 1395 implementations SHOULD implement additional [SASL] mechanisms that 1396 do not use plaintext passwords, such the GSSAPI mechanism 1397 described in [SASL] and/or the SCRAM-SHA-256/SCRAM-SHA-256-PLUS 1398 [SCRAM-SHA-256] mechanisms. 1400 Servers and clients can support multiple authentication mechanisms. 1401 The server SHOULD list its supported authentication mechanisms in the 1402 response to the CAPABILITY command so that the client knows which 1403 authentication mechanisms to use. 1405 A server MAY include a CAPABILITY response code in the tagged OK 1406 response of a successful AUTHENTICATE command in order to send 1407 capabilities automatically. It is unnecessary for a client to send a 1408 separate CAPABILITY command if it recognizes these automatic 1409 capabilities. This should only be done if a security layer was not 1410 negotiated by the AUTHENTICATE command, because the tagged OK 1411 response as part of an AUTHENTICATE command is not protected by 1412 encryption/integrity checking. [SASL] requires the client to re- 1413 issue a CAPABILITY command in this case. The server MAY advertise 1414 different capabilities after a successful AUTHENTICATE command. 1416 If an AUTHENTICATE command fails with a NO response, the client MAY 1417 try another authentication mechanism by issuing another AUTHENTICATE 1418 command. It MAY also attempt to authenticate by using the LOGIN 1419 command (see Section 6.2.3 for more detail). In other words, the 1420 client MAY request authentication types in decreasing order of 1421 preference, with the LOGIN command as a last resort. 1423 The authorization identity passed from the client to the server 1424 during the authentication exchange is interpreted by the server as 1425 the user name whose privileges the client is requesting. 1427 Example: S: * OK IMAP4rev2 Server 1428 C: A001 AUTHENTICATE GSSAPI 1429 S: + 1430 C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw 1431 MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0 1432 b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW 1433 Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA 1434 cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX 1435 AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y 1436 C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb 1437 I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi 1438 vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL 1439 pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n 1440 FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE 1441 NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx 1442 O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB 1443 vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg== 1444 S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC 1445 AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0 1446 uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg== 1447 C: 1448 S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe 1449 ceP2CWY0SR0fAQAgAAQEBAQ= 1450 C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP 1451 wkhbfa2QteAQAgAG1yYwE= 1452 S: A001 OK GSSAPI authentication successful 1454 Note: The line breaks within server challenges and client responses 1455 are for editorial clarity and are not in real authenticators. 1457 6.2.3. LOGIN Command 1459 Arguments: user name 1460 password 1462 Responses: no specific responses for this command 1464 Result: OK - login completed, now in authenticated state 1465 NO - login failure: user name or password rejected 1466 BAD - command unknown or arguments invalid 1468 The LOGIN command identifies the client to the server and carries the 1469 plaintext password authenticating this user. 1471 A server MAY include a CAPABILITY response code in the tagged OK 1472 response to a successful LOGIN command in order to send capabilities 1473 automatically. It is unnecessary for a client to send a separate 1474 CAPABILITY command if it recognizes these automatic capabilities. 1476 Example: C: a001 LOGIN SMITH SESAME 1477 S: a001 OK LOGIN completed 1479 Note: Use of the LOGIN command over an insecure network (such as the 1480 Internet) is a security risk, because anyone monitoring network 1481 traffic can obtain plaintext passwords. The LOGIN command SHOULD NOT 1482 be used except as a last resort, and it is recommended that client 1483 implementations have a means to disable any automatic use of the 1484 LOGIN command. 1486 Unless either the client is accessing IMAP service on IMAPS port 1487 [RFC8314], the STARTTLS command has been negotiated or some other 1488 mechanism that protects the session from password snooping has been 1489 provided, a server implementation MUST implement a configuration in 1490 which it advertises the LOGINDISABLED capability and does NOT permit 1491 the LOGIN command. Server sites SHOULD NOT use any configuration 1492 which permits the LOGIN command without such a protection mechanism 1493 against password snooping. A client implementation MUST NOT send a 1494 LOGIN command if the LOGINDISABLED capability is advertised. 1496 6.3. Client Commands - Authenticated State 1498 In the authenticated state, commands that manipulate mailboxes as 1499 atomic entities are permitted. Of these commands, the SELECT and 1500 EXAMINE commands will select a mailbox for access and enter the 1501 selected state. 1503 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1504 the following commands are valid in the authenticated state: ENABLE, 1505 SELECT, EXAMINE, NAMESPACE, CREATE, DELETE, RENAME, SUBSCRIBE, 1506 UNSUBSCRIBE, LIST, STATUS, APPEND and IDLE. 1508 6.3.1. ENABLE Command 1510 Arguments: capability names 1512 Responses: no specific responses for this command 1514 Result: OK - Relevant capabilities enabled 1515 BAD - No arguments, or syntax error in an argument 1517 Several IMAP extensions allow the server to return unsolicited 1518 responses specific to these extensions in certain circumstances. 1519 However, servers cannot send those unsolicited responses (with the 1520 exception of response codes (see Section 7.1) included in tagged or 1521 untagged OK/NO/BAD responses, which can always be sent) until they 1522 know that the clients support such extensions and thus won't choke on 1523 the extension response data. 1525 The ENABLE command provides an explicit indication from the client 1526 that it supports particular extensions. It is designed such that the 1527 client can send a simple constant string with the extensions it 1528 supports, and the server will enable the shared subset that both 1529 support. 1531 The ENABLE command takes a list of capability names, and requests the 1532 server to enable the named extensions. Once enabled using ENABLE, 1533 each extension remains active until the IMAP connection is closed. 1534 For each argument, the server does the following: 1536 o If the argument is not an extension known to the server, the 1537 server MUST ignore the argument. 1539 o If the argument is an extension known to the server, and it is not 1540 specifically permitted to be enabled using ENABLE, the server MUST 1541 ignore the argument. (Note that knowing about an extension 1542 doesn't necessarily imply supporting that extension.) 1544 o If the argument is an extension that is supported by the server 1545 and that needs to be enabled, the server MUST enable the extension 1546 for the duration of the connection. Note that once an extension 1547 is enabled, there is no way to disable it. 1549 If the ENABLE command is successful, the server MUST send an untagged 1550 ENABLED response Section 7.2.1. 1552 Clients SHOULD only include extensions that need to be enabled by the 1553 server. For example, a client can enable IMAP4rev2 specific 1554 behaviour when both IMAP4rev1 and IMAP4rev2 are advertised in the 1555 CAPABILITY response. Future RFCs may add to this list. 1557 The ENABLE command is only valid in the authenticated state, before 1558 any mailbox is selected. Clients MUST NOT issue ENABLE once they 1559 SELECT/EXAMINE a mailbox; however, server implementations don't have 1560 to check that no mailbox is selected or was previously selected 1561 during the duration of a connection. 1563 The ENABLE command can be issued multiple times in a session. It is 1564 additive; i.e., "ENABLE a b", followed by "ENABLE c" is the same as a 1565 single command "ENABLE a b c". When multiple ENABLE commands are 1566 issued, each corresponding ENABLED response SHOULD only contain 1567 extensions enabled by the corresponding ENABLE command, i.e. for the 1568 above example, the ENABLED response to "ENABLE c" should not contain 1569 "a" or "b". 1571 There are no limitations on pipelining ENABLE. For example, it is 1572 possible to send ENABLE and then immediately SELECT, or a LOGIN 1573 immediately followed by ENABLE. 1575 The server MUST NOT change the CAPABILITY list as a result of 1576 executing ENABLE; i.e., a CAPABILITY command issued right after an 1577 ENABLE command MUST list the same capabilities as a CAPABILITY 1578 command issued before the ENABLE command. This is demonstrated in 1579 the following example: 1581 C: t1 CAPABILITY 1582 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1583 S: t1 OK foo 1584 C: t2 ENABLE CONDSTORE X-GOOD-IDEA 1585 S: * ENABLED X-GOOD-IDEA 1586 S: t2 OK foo 1587 C: t3 CAPABILITY 1588 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1589 S: t3 OK foo again 1591 In the following example, the client enables CONDSTORE: 1593 C: a1 ENABLE CONDSTORE 1594 S: * ENABLED CONDSTORE 1595 S: a1 OK Conditional Store enabled 1597 6.3.1.1. Note to Designers of Extensions That May Use the ENABLE 1598 Command 1600 Designers of IMAP extensions are discouraged from creating extensions 1601 that require ENABLE unless there is no good alternative design. 1602 Specifically, extensions that cause potentially incompatible behavior 1603 changes to deployed server responses (and thus benefit from ENABLE) 1604 have a higher complexity cost than extensions that do not. 1606 6.3.2. SELECT Command 1608 Arguments: mailbox name 1610 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1611 REQUIRED OK untagged responses: PERMANENTFLAGS, 1612 UIDNEXT, UIDVALIDITY 1613 REQUIRED untagged response: LIST 1615 Result: OK - select completed, now in selected state 1616 NO - select failure, now in authenticated state: no 1617 such mailbox, can't access mailbox 1618 BAD - command unknown or arguments invalid 1620 The SELECT command selects a mailbox so that messages in the mailbox 1621 can be accessed. Before returning an OK to the client, the server 1622 MUST send the following untagged data to the client. (The order of 1623 individual responses is not important.) Note that earlier versions 1624 of this protocol (e.g. IMAP2bis) only required the FLAGS and EXISTS 1625 untagged data; consequently, client implementations SHOULD implement 1626 default behavior for missing data as discussed with the individual 1627 item. 1629 FLAGS Defined flags in the mailbox. See the description of the 1630 FLAGS response for more detail. 1632 EXISTS The number of messages in the mailbox. See the 1633 description of the EXISTS response for more detail. 1635 LIST The server MUST return a LIST response with the mailbox name. 1636 If the server allows de-normalized UTF-8 mailbox names (see 1637 Section 5.1) and the supplied mailbox name differs from the 1638 normalized version, the server MUST return LIST with the OLDNAME 1639 extended data item. See Section 6.3.9.7 for more details. 1641 OK [PERMANENTFLAGS ()] A list of message flags that 1642 the client can change permanently. If this is missing, the client 1643 should assume that all flags can be changed permanently. 1645 OK [UIDNEXT ] The next unique identifier value. Refer to 1646 Section 2.3.1.1 for more information. 1648 OK [UIDVALIDITY ] The unique identifier validity value. Refer to 1649 Section 2.3.1.1 for more information. 1651 Only one mailbox can be selected at a time in a connection; 1652 simultaneous access to multiple mailboxes requires multiple 1653 connections. The SELECT command automatically deselects any 1654 currently selected mailbox before attempting the new selection. 1655 Consequently, if a mailbox is selected and a SELECT command that 1656 fails is attempted, no mailbox is selected. When deselecting a 1657 selected mailbox, the server MUST return an untagged OK response with 1658 the "[CLOSED]" response code when the currently selected mailbox is 1659 closed (see Paragraph 10). 1661 If the client is permitted to modify the mailbox, the server SHOULD 1662 prefix the text of the tagged OK response with the "[READ-WRITE]" 1663 response code. 1665 If the client is not permitted to modify the mailbox but is permitted 1666 read access, the mailbox is selected as read-only, and the server 1667 MUST prefix the text of the tagged OK response to SELECT with the 1668 "[READ-ONLY]" response code. Read-only access through SELECT differs 1669 from the EXAMINE command in that certain read-only mailboxes MAY 1670 permit the change of permanent state on a per-user (as opposed to 1671 global) basis. Netnews messages marked in a server-based .newsrc 1672 file are an example of such per-user permanent state that can be 1673 modified with read-only mailboxes. 1675 Example: C: A142 SELECT INBOX 1676 S: * 172 EXISTS 1677 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1678 S: * OK [UIDNEXT 4392] Predicted next UID 1679 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1680 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1681 S: * LIST () "/" INBOX 1682 S: A142 OK [READ-WRITE] SELECT completed 1684 Example: C: A142 SELECT INBOX 1685 S: * 172 EXISTS 1686 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1687 S: * OK [UIDNEXT 4392] Predicted next UID 1688 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1689 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1690 S: A142 OK [READ-WRITE] SELECT completed 1691 [...some time later...] 1692 C: A143 SELECT Drafts 1693 S: * OK [CLOSED] Previous mailbox is now closed 1694 S: * 5 EXISTS 1695 S: * OK [UIDVALIDITY 9877410381] UIDs valid 1696 S: * OK [UIDNEXT 102] Predicted next UID 1697 S: * LIST () "/" Drafts 1698 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1699 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Answered 1700 \Flagged \Draft \*)] System flags and keywords allowed 1701 S: A143 OK [READ-WRITE] SELECT completed 1703 Note that IMAP4rev1 compliant servers can also send the untagged 1704 RECENT response which was deprecated in IMAP4rev2. E.g. "* 0 1705 RECENT". Pure IMAP4rev2 clients are advised to ignore the untagged 1706 RECENT response. 1708 6.3.3. EXAMINE Command 1710 Arguments: mailbox name 1712 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1713 REQUIRED OK untagged responses: PERMANENTFLAGS, 1714 UIDNEXT, UIDVALIDITY 1715 REQUIRED untagged response: LIST 1717 Result: OK - examine completed, now in selected state 1718 NO - examine failure, now in authenticated state: no 1719 such mailbox, can't access mailbox BAD - command unknown 1720 or arguments invalid 1722 The EXAMINE command is identical to SELECT and returns the same 1723 output; however, the selected mailbox is identified as read-only. No 1724 changes to the permanent state of the mailbox, including per-user 1725 state, are permitted. 1727 The text of the tagged OK response to the EXAMINE command MUST begin 1728 with the "[READ-ONLY]" response code. 1730 Example: C: A932 EXAMINE blurdybloop 1731 S: * 17 EXISTS 1732 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1733 S: * OK [UIDNEXT 4392] Predicted next UID 1734 S: * LIST () "/" blurdybloop 1735 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1736 S: * OK [PERMANENTFLAGS ()] No permanent flags permitted 1737 S: A932 OK [READ-ONLY] EXAMINE completed 1739 6.3.4. CREATE Command 1741 Arguments: mailbox name 1743 Responses: OPTIONAL untagged response: LIST 1745 Result: OK - create completed 1746 NO - create failure: can't create mailbox with that name 1747 BAD - command unknown or arguments invalid 1749 The CREATE command creates a mailbox with the given name. An OK 1750 response is returned only if a new mailbox with that name has been 1751 created. It is an error to attempt to create INBOX or a mailbox with 1752 a name that refers to an extant mailbox. Any error in creation will 1753 return a tagged NO response. If a client attempts to create a UTF-8 1754 mailbox name that is not a valid Net-Unicode name, the server MUST 1755 reject the creation or convert the name to Net-Unicode prior to 1756 creating the mailbox. If the server decides to convert (normalize) 1757 the name, it SHOULD return an untagged LIST with OLDNAME extended 1758 data item, with the OLDNAME value being the supplied mailbox name and 1759 the name parameter being the normalized mailbox name. (See 1760 Section 6.3.9.7 for more details.) 1762 Mailboxes created in one IMAP session MAY be announced to other IMAP 1763 sessions using unsolicited LIST response. If the server 1764 automatically subscribes a mailbox when it is created, then the 1765 unsolicited LIST response for each affected subscribed mailbox name 1766 MUST include the \Subscribed attribute. 1768 If the mailbox name is suffixed with the server's hierarchy separator 1769 character (as returned from the server by a LIST command), this is a 1770 declaration that the client intends to create mailbox names under 1771 this name in the hierarchy. Server implementations that do not 1772 require this declaration MUST ignore the declaration. In any case, 1773 the name created is without the trailing hierarchy delimiter. 1775 If the server's hierarchy separator character appears elsewhere in 1776 the name, the server SHOULD create any superior hierarchical names 1777 that are needed for the CREATE command to be successfully completed. 1778 In other words, an attempt to create "foo/bar/zap" on a server in 1779 which "/" is the hierarchy separator character SHOULD create foo/ and 1780 foo/bar/ if they do not already exist. 1782 If a new mailbox is created with the same name as a mailbox which was 1783 deleted, its unique identifiers MUST be greater than any unique 1784 identifiers used in the previous incarnation of the mailbox UNLESS 1785 the new incarnation has a different unique identifier validity value. 1786 See the description of the UID command for more detail. 1788 Example: C: A003 CREATE owatagusiam/ 1789 S: A003 OK CREATE completed 1790 C: A004 CREATE owatagusiam/blurdybloop 1791 S: A004 OK CREATE completed 1792 C: A005 CREATE NonNormalized 1793 S: * LIST () "/" "Normalized" ("OLDNAME" ("NonNormalized")) 1794 S: A005 OK CREATE completed 1796 (in the last example imagine that "NonNormalized" is 1797 a non NFC normalized Unicode mailbox name and that 1798 "Normalized" is its NFC normalized version.) 1800 Note: The interpretation of this example depends on whether "/" 1801 was returned as the hierarchy separator from LIST. If "/" is the 1802 hierarchy separator, a new level of hierarchy named "owatagusiam" 1803 with a member called "blurdybloop" is created. Otherwise, two 1804 mailboxes at the same hierarchy level are created. 1806 6.3.5. DELETE Command 1808 Arguments: mailbox name 1810 Responses: OPTIONAL untagged response: LIST 1812 Result: OK - delete completed 1813 NO - delete failure: can't delete mailbox with that name 1814 BAD - command unknown or arguments invalid 1816 The DELETE command permanently removes the mailbox with the given 1817 name. A tagged OK response is returned only if the mailbox has been 1818 deleted. It is an error to attempt to delete INBOX or a mailbox name 1819 that does not exist. 1821 The DELETE command MUST NOT remove inferior hierarchical names. For 1822 example, if a mailbox "foo" has an inferior "foo.bar" (assuming "." 1823 is the hierarchy delimiter character), removing "foo" MUST NOT remove 1824 "foo.bar". It is an error to attempt to delete a name that has 1825 inferior hierarchical names and also has the \Noselect mailbox name 1826 attribute (see the description of the LIST response for more 1827 details). 1829 It is permitted to delete a name that has inferior hierarchical names 1830 and does not have the \Noselect mailbox name attribute. If the 1831 server implementation does not permit deleting the name while 1832 inferior hierarchical names exists then it SHOULD disallow the DELETE 1833 command by returning a tagged NO response. The NO response SHOULD 1834 include the HASCHILDREN response code. Alternatively the server MAY 1835 allow the DELETE command, but sets the \Noselect mailbox name 1836 attribute for that name. 1838 If the server returns OK response, all messages in that mailbox are 1839 removed by the DELETE command. 1841 The value of the highest-used unique identifier of the deleted 1842 mailbox MUST be preserved so that a new mailbox created with the same 1843 name will not reuse the identifiers of the former incarnation, UNLESS 1844 the new incarnation has a different unique identifier validity value. 1845 See the description of the UID command for more detail. 1847 If the server decides to convert (normalize) the mailbox name, it 1848 SHOULD return an untagged LIST with the "\NonExistent" attribute and 1849 OLDNAME extended data item, with the OLDNAME value being the supplied 1850 mailbox name and the name parameter being the normalized mailbox 1851 name. (See Section 6.3.9.7 for more details.) 1853 Mailboxes deleted in one IMAP session MAY be announced to other IMAP 1854 sessions using unsolicited LIST response, containing the 1855 "\NonExistent" attribute. 1857 Examples: C: A682 LIST "" * 1858 S: * LIST () "/" blurdybloop 1859 S: * LIST (\Noselect) "/" foo 1860 S: * LIST () "/" foo/bar 1861 S: A682 OK LIST completed 1862 C: A683 DELETE blurdybloop 1863 S: A683 OK DELETE completed 1864 C: A684 DELETE foo 1865 S: A684 NO Name "foo" has inferior hierarchical names 1866 C: A685 DELETE foo/bar 1867 S: A685 OK DELETE Completed 1868 C: A686 LIST "" * 1869 S: * LIST (\Noselect) "/" foo 1870 S: A686 OK LIST completed 1871 C: A687 DELETE foo 1872 S: A687 OK DELETE Completed 1873 C: A82 LIST "" * 1874 S: * LIST () "." blurdybloop 1875 S: * LIST () "." foo 1876 S: * LIST () "." foo.bar 1877 S: A82 OK LIST completed 1878 C: A83 DELETE blurdybloop 1879 S: A83 OK DELETE completed 1880 C: A84 DELETE foo 1881 S: A84 OK DELETE Completed 1882 C: A85 LIST "" * 1883 S: * LIST () "." foo.bar 1884 S: A85 OK LIST completed 1885 C: A86 LIST "" % 1886 S: * LIST (\Noselect) "." foo 1887 S: A86 OK LIST completed 1889 6.3.6. RENAME Command 1891 Arguments: existing mailbox name 1892 new mailbox name 1894 Responses: OPTIONAL untagged response: LIST 1896 Result: OK - rename completed 1897 NO - rename failure: can't rename mailbox with that name, 1898 can't rename to mailbox with that name 1899 BAD - command unknown or arguments invalid 1901 The RENAME command changes the name of a mailbox. A tagged OK 1902 response is returned only if the mailbox has been renamed. It is an 1903 error to attempt to rename from a mailbox name that does not exist or 1904 to a mailbox name that already exists. Any error in renaming will 1905 return a tagged NO response. 1907 If the name has inferior hierarchical names, then the inferior 1908 hierarchical names MUST also be renamed. For example, a rename of 1909 "foo" to "zap" will rename "foo/bar" (assuming "/" is the hierarchy 1910 delimiter character) to "zap/bar". 1912 If the server's hierarchy separator character appears in the name, 1913 the server SHOULD create any superior hierarchical names that are 1914 needed for the RENAME command to complete successfully. In other 1915 words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a 1916 server in which "/" is the hierarchy separator character in the 1917 corresponding namespace SHOULD create baz/ and baz/rag/ if they do 1918 not already exist. 1920 The value of the highest-used unique identifier of the old mailbox 1921 name MUST be preserved so that a new mailbox created with the same 1922 name will not reuse the identifiers of the former incarnation, UNLESS 1923 the new incarnation has a different unique identifier validity value. 1924 See the description of the UID command for more detail. 1926 Renaming INBOX is permitted, and has special behavior. (Note that 1927 some servers disallow renaming INBOX, so clients need to be able to 1928 handle such RENAME failing). It moves all messages in INBOX to a new 1929 mailbox with the given name, leaving INBOX empty. If the server 1930 implementation supports inferior hierarchical names of INBOX, these 1931 are unaffected by a rename of INBOX. 1933 If the server allows creation of mailboxes with names that are not 1934 valid Net-Unicode names, the server normalizes both the existing 1935 mailbox name parameter and the new mailbox name parameter. If the 1936 normalized version of any of these 2 parameters differs from the 1937 corresponding supplied version, the server SHOULD return an untagged 1938 LIST response with OLDNAME extended data item, with the OLDNAME value 1939 being the supplied existing mailbox name and the name parameter being 1940 the normalized new mailbox name (see Section 6.3.9.7). This would 1941 allow the client to correlate supplied name with the normalized name. 1943 Mailboxes renamed in one IMAP session MAY be announced to other IMAP 1944 sessions using unsolicited LIST response with OLDNAME extended data 1945 item. 1947 In both of the above cases: if the server automatically subscribes a 1948 mailbox when it is renamed, then the unsolicited LIST response for 1949 each affected subscribed mailbox name MUST include the \Subscribed 1950 attribute. No unsolicited LIST responses need to be sent for 1951 children mailboxes, if any. When INBOX is successfully renamed, a 1952 new INBOX is assumed to be created. No unsolicited LIST responses 1953 need to be sent for INBOX in this case. 1955 Examples: C: A682 LIST "" * 1956 S: * LIST () "/" blurdybloop 1957 S: * LIST (\Noselect) "/" foo 1958 S: * LIST () "/" foo/bar 1959 S: A682 OK LIST completed 1960 C: A683 RENAME blurdybloop sarasoop 1961 S: A683 OK RENAME completed 1962 C: A684 RENAME foo zowie 1963 S: A684 OK RENAME Completed 1964 C: A685 LIST "" * 1965 S: * LIST () "/" sarasoop 1966 S: * LIST (\Noselect) "/" zowie 1967 S: * LIST () "/" zowie/bar 1968 S: A685 OK LIST completed 1970 C: Z432 LIST "" * 1971 S: * LIST () "." INBOX 1972 S: * LIST () "." INBOX.bar 1973 S: Z432 OK LIST completed 1974 C: Z433 RENAME INBOX old-mail 1975 S: Z433 OK RENAME completed 1976 C: Z434 LIST "" * 1977 S: * LIST () "." INBOX 1978 S: * LIST () "." INBOX.bar 1979 S: * LIST () "." old-mail 1980 S: Z434 OK LIST completed 1982 Note that renaming a mailbox doesn't update subscription information 1983 on the original name. To keep subscription information in sync, the 1984 following sequence of commands can be used: 1986 C: 1001 RENAME X Y 1987 C: 1002 SUBSCRIBE Y 1988 C: 1003 UNSUBSCRIBE X 1990 Note that the above sequence of commands doesn't account for updating 1991 subscription for any children mailboxes of mailbox X. 1993 6.3.7. SUBSCRIBE Command 1995 Arguments: mailbox 1997 Responses: no specific responses for this command 1999 Result: OK - subscribe completed 2000 NO - subscribe failure: can't subscribe to that name 2001 BAD - command unknown or arguments invalid 2003 The SUBSCRIBE command adds the specified mailbox name to the server's 2004 set of "active" or "subscribed" mailboxes as returned by the LIST 2005 (SUBSCRIBED) command. This command returns a tagged OK response if 2006 the subscription is successful or if the mailbox is already 2007 subscribed. 2009 A server MAY validate the mailbox argument to SUBSCRIBE to verify 2010 that it exists. However, it SHOULD NOT unilaterally remove an 2011 existing mailbox name from the subscription list even if a mailbox by 2012 that name no longer exists. 2014 Note: This requirement is because a server site can choose to 2015 routinely remove a mailbox with a well-known name (e.g., "system- 2016 alerts") after its contents expire, with the intention of 2017 recreating it when new contents are appropriate. 2019 Example: C: A002 SUBSCRIBE #news.comp.mail.mime 2020 S: A002 OK SUBSCRIBE completed 2022 6.3.8. UNSUBSCRIBE Command 2024 Arguments: mailbox name 2026 Responses: no specific responses for this command 2028 Result: OK - unsubscribe completed 2029 NO - unsubscribe failure: can't unsubscribe that name 2030 BAD - command unknown or arguments invalid 2032 The UNSUBSCRIBE command removes the specified mailbox name from the 2033 server's set of "active" or "subscribed" mailboxes as returned by the 2034 LIST (SUBSCRIBED) command. This command returns a tagged OK response 2035 if the unsubscription is successful or if the mailbox is not 2036 subscribed. 2038 Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime 2039 S: A002 OK UNSUBSCRIBE completed 2041 6.3.9. LIST Command 2043 Arguments (basic): reference name 2044 mailbox name with possible wildcards 2046 Arguments (extended): selection options (OPTIONAL) 2047 reference name 2048 mailbox patterns 2049 return options (OPTIONAL) 2051 Responses: untagged responses: LIST 2053 Result: OK - list completed 2054 NO - list failure: can't list that reference or name 2055 BAD - command unknown or arguments invalid 2057 The LIST command returns a subset of names from the complete set of 2058 all names available to the client. Zero or more untagged LIST 2059 replies are returned, containing the name attributes, hierarchy 2060 delimiter, name, and possible extension information; see the 2061 description of the LIST reply for more detail. 2063 The LIST command SHOULD return its data quickly, without undue delay. 2064 For example, it SHOULD NOT go to excess trouble to calculate the 2065 \Marked or \Unmarked status or perform other processing; if each name 2066 requires 1 second of processing, then a list of 1200 names would take 2067 20 minutes! 2069 The extended LIST command, originally introduced in [RFC5258], 2070 provides capabilities beyond that of the original IMAP LIST command. 2071 The extended syntax is being used if one or more of the following 2072 conditions is true: 2074 1. if the first word after the command name begins with a 2075 parenthesis ("LIST selection options"); 2077 2. if the second word after the command name begins with a 2078 parenthesis; 2080 3. if the LIST command has more than 2 parameters ("LIST return 2081 options") 2083 An empty ("" string) reference name argument indicates that the 2084 mailbox name is interpreted as by SELECT. The returned mailbox names 2085 MUST match the supplied mailbox name pattern(s). A non-empty 2086 reference name argument is the name of a mailbox or a level of 2087 mailbox hierarchy, and indicates the context in which the mailbox 2088 name is interpreted. Clients SHOULD use the empty reference 2089 argument. 2091 In the basic syntax only, an empty ("" string) mailbox name argument 2092 is a special request to return the hierarchy delimiter and the root 2093 name of the name given in the reference. The value returned as the 2094 root MAY be the empty string if the reference is non-rooted or is an 2095 empty string. In all cases, a hierarchy delimiter (or NIL if there 2096 is no hierarchy) is returned. This permits a client to get the 2097 hierarchy delimiter (or find out that the mailbox names are flat) 2098 even when no mailboxes by that name currently exist. 2100 In the extended syntax, any mailbox name arguments that are empty 2101 strings are ignored. There is no special meaning for empty mailbox 2102 names when the extended syntax is used. 2104 The reference and mailbox name arguments are interpreted into a 2105 canonical form that represents an unambiguous left-to-right 2106 hierarchy. The returned mailbox names will be in the interpreted 2107 form, that we call "canonical LIST pattern" later in this document. 2108 To define the term "canonical LIST pattern" formally: it refers to 2109 the canonical pattern constructed internally by the server from the 2110 reference and mailbox name arguments. 2112 Note: The interpretation of the reference argument is 2113 implementation-defined. It depends upon whether the server 2114 implementation has a concept of the "current working directory" 2115 and leading "break out characters", which override the current 2116 working directory. 2118 For example, on a server which exports a UNIX or NT filesystem, 2119 the reference argument contains the current working directory, and 2120 the mailbox name argument would contain the name as interpreted in 2121 the current working directory. 2123 If a server implementation has no concept of break out characters, 2124 the canonical form is normally the reference name appended with 2125 the mailbox name. Note that if the server implements the 2126 namespace convention (Section 5.1.2.1), "#" is a break out 2127 character and must be treated as such. 2129 If the reference argument is not a level of mailbox hierarchy 2130 (that is, it is a \NoInferiors name), and/or the reference 2131 argument does not end with the hierarchy delimiter, it is 2132 implementation-dependent how this is interpreted. For example, a 2133 reference of "foo/bar" and mailbox name of "rag/baz" could be 2134 interpreted as "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/ 2135 baz". A client SHOULD NOT use such a reference argument except at 2136 the explicit request of the user. A hierarchical browser MUST NOT 2137 make any assumptions about server interpretation of the reference 2138 unless the reference is a level of mailbox hierarchy AND ends with 2139 the hierarchy delimiter. 2141 Any part of the reference argument that is included in the 2142 interpreted form SHOULD prefix the interpreted form. It SHOULD also 2143 be in the same form as the reference name argument. This rule 2144 permits the client to determine if the returned mailbox name is in 2145 the context of the reference argument, or if something about the 2146 mailbox argument overrode the reference argument. Without this rule, 2147 the client would have to have knowledge of the server's naming 2148 semantics including what characters are "breakouts" that override a 2149 naming context. 2151 For example, here are some examples of how references 2152 and mailbox names might be interpreted on a UNIX-based 2153 server: 2155 Reference Mailbox Name Interpretation 2156 ------------ ------------ -------------- 2157 ~smith/Mail/ foo.* ~smith/Mail/foo.* 2158 archive/ % archive/% 2159 #news. comp.mail.* #news.comp.mail.* 2160 ~smith/Mail/ /usr/doc/foo /usr/doc/foo 2161 archive/ ~fred/Mail/* ~fred/Mail/* 2163 The first three examples demonstrate interpretations in 2164 the context of the reference argument. Note that 2165 "~smith/Mail" SHOULD NOT be transformed into something 2166 like "/u2/users/smith/Mail", or it would be impossible 2167 for the client to determine that the interpretation was 2168 in the context of the reference. 2170 The character "*" is a wildcard, and matches zero or more characters 2171 at this position. The character "%" is similar to "*", but it does 2172 not match a hierarchy delimiter. If the "%" wildcard is the last 2173 character of a mailbox name argument, matching levels of hierarchy 2174 are also returned. If these levels of hierarchy are not also 2175 selectable mailboxes, they are returned with the \Noselect mailbox 2176 name attribute (see the description of the LIST response for more 2177 details). 2179 Any syntactically valid pattern that is not accepted by a server for 2180 any reason MUST be silently ignored. I.e. it results in no LIST 2181 responses and the LIST command still returns tagged OK response. 2183 Selection options tell the server to limit the mailbox names that are 2184 selected by the LIST operation. If selection options are used, the 2185 mailboxes returned are those that match both the list of canonical 2186 LIST patterns and the selection options. Unless a particular 2187 selection option provides special rules, the selection options are 2188 cumulative: a mailbox that matches the mailbox patterns is selected 2189 only if it also matches all of the selection options. (An example of 2190 a selection option with special rules is the RECURSIVEMATCH option.) 2191 Return options control what information is returned for each matched 2192 mailbox. Return options MUST NOT cause the server to report 2193 information about additional mailbox names other than those that 2194 match the canonical LIST patterns and selection options. If no 2195 return options are specified, the client is only expecting 2196 information about mailbox attributes. The server MAY return other 2197 information about the matched mailboxes, and clients MUST be able to 2198 handle that situation. 2200 Initial selection options and return options are defined in the 2201 following subsections, and new ones will also be defined in 2202 extensions. Initial options defined in this document MUST be 2203 supported. Each non-initial option will be enabled by a capability 2204 string (one capability may enable multiple options), and a client 2205 MUST NOT send an option for which the server has not advertised 2206 support. A server MUST respond to options it does not recognize with 2207 a BAD response. The client SHOULD NOT specify any option more than 2208 once; however, if the client does this, the server MUST act as if it 2209 received the option only once. The order in which options are 2210 specified by the client is not significant. 2212 In general, each selection option except RECURSIVEMATCH will have a 2213 corresponding return option with the same name. The REMOTE selection 2214 option is an anomaly in this regard, and does not have a 2215 corresponding return option. That is because it expands, rather than 2216 restricts, the set of mailboxes that are returned. Future extensions 2217 to this specification should keep this parallelism in mind and define 2218 a pair of corresponding selection and return options. 2220 Server implementations are permitted to "hide" otherwise accessible 2221 mailboxes from the wildcard characters, by preventing certain 2222 characters or names from matching a wildcard in certain situations. 2223 For example, a UNIX-based server might restrict the interpretation of 2224 "*" so that an initial "/" character does not match. 2226 The special name INBOX is included in the output from LIST, if INBOX 2227 is supported by this server for this user and if the uppercase string 2228 "INBOX" matches the interpreted reference and mailbox name arguments 2229 with wildcards as described above. The criteria for omitting INBOX 2230 is whether SELECT INBOX will return failure; it is not relevant 2231 whether the user's real INBOX resides on this or some other server. 2233 6.3.9.1. LIST Selection Options 2235 The selection options defined in this specification are as follows: 2237 SUBSCRIBED - causes the LIST command to list subscribed names, 2238 rather than the existing mailboxes. This will often be a subset 2239 of the actual mailboxes. It's also possible for this list to 2240 contain the names of mailboxes that don't exist. In any case, the 2241 list MUST include exactly those mailbox names that match the 2242 canonical list pattern and are subscribed to. 2244 This option defines a mailbox attribute, "\Subscribed", that 2245 indicates that a mailbox name is subscribed to. The "\Subscribed" 2246 attribute MUST be supported and MUST be accurately computed when 2247 the SUBSCRIBED selection option is specified. 2249 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 2250 return option (see below). 2252 REMOTE - causes the LIST command to show remote mailboxes as well as 2253 local ones, as described in [RFC2193]. This option is intended to 2254 replace the RLIST command and, in conjunction with the SUBSCRIBED 2255 selection option, the RLSUB command. Servers that don't support 2256 remote mailboxes just ignore this option. 2258 This option defines a mailbox attribute, "\Remote", that indicates 2259 that a mailbox is a remote mailbox. The "\Remote" attribute MUST 2260 be accurately computed when the REMOTE option is specified. 2262 The REMOTE selection option has no interaction with other options. 2263 Its effect is to tell the server to apply the other options, if 2264 any, to remote mailboxes, in addition to local ones. In 2265 particular, it has no interaction with RECURSIVEMATCH (see below). 2266 A request for (REMOTE RECURSIVEMATCH) is invalid, because a 2267 request for (RECURSIVEMATCH) is also invalid. A request for 2268 (REMOTE RECURSIVEMATCH SUBSCRIBED) is asking for all subscribed 2269 mailboxes, both local and remote. 2271 RECURSIVEMATCH - this option forces the server to return information 2272 about parent mailboxes that don't match other selection options, 2273 but have some submailboxes that do. Information about children is 2274 returned in the CHILDINFO extended data item, as described in 2275 Section 6.3.9.6. 2277 Note 1: In order for a parent mailbox to be returned, it still has 2278 to match the canonical LIST pattern. 2280 Note 2: When returning the CHILDINFO extended data item, it 2281 doesn't matter whether or not the submailbox matches the canonical 2282 LIST pattern. See also example 9 in Section 6.3.9.8. 2284 The RECURSIVEMATCH option MUST NOT occur as the only selection 2285 option (or only with REMOTE), as it only makes sense when other 2286 selection options are also used. The server MUST return BAD 2287 tagged response in such case. 2289 Note that even if the RECURSIVEMATCH option is specified, the 2290 client MUST still be able to handle a case when a CHILDINFO 2291 extended data item is returned and there are no submailboxes that 2292 meet the selection criteria of the subsequent LIST command, as 2293 they can be deleted/renamed after the LIST response was sent, but 2294 before the client had a chance to access them. 2296 6.3.9.2. LIST Return Options 2298 The return options defined in this specification are as follows: 2300 SUBSCRIBED - causes the LIST command to return subscription state 2301 for all matching mailbox names. The "\Subscribed" attribute MUST 2302 be supported and MUST be accurately computed when the SUBSCRIBED 2303 return option is specified. Further, all mailbox flags MUST be 2304 accurately computed (this differs from the behavior of the 2305 obsolete LSUB command from IMAP4rev1). 2307 CHILDREN - requests mailbox child information as originally proposed 2308 in [RFC3348]. See Section 6.3.9.5, below, for details. This 2309 option MUST be supported by all servers. 2311 STATUS - requests STATUS response for each matching mailbox. 2313 This option takes STATUS data items as parameters. For each 2314 selectable mailbox matching the list pattern and selection 2315 options, the server MUST return an untagged LIST response 2316 followed by an untagged STATUS response containing the 2317 information requested in the STATUS return option, except for 2318 some cases described below. 2320 If an attempted STATUS for a listed mailbox fails because the 2321 mailbox can't be selected (e.g., if the "l" ACL right [RFC4314] 2322 is granted to the mailbox and the "r" right is not granted, or 2323 due to a race condition between LIST and STATUS changing the 2324 mailbox to \NoSelect), the STATUS response MUST NOT be returned 2325 and the LIST response MUST include the \NoSelect attribute. 2326 This means the server may have to buffer the LIST reply until 2327 it has successfully looked up the necessary STATUS information. 2329 If the server runs into unexpected problems while trying to 2330 look up the STATUS information, it MAY drop the corresponding 2331 STATUS reply. In such a situation, the LIST command would 2332 still return a tagged OK reply. 2334 6.3.9.3. General Principles for Returning LIST Responses 2336 This section outlines several principles that can be used by server 2337 implementations of this document to decide whether a LIST response 2338 should be returned, as well as how many responses and what kind of 2339 information they may contain. 2341 1. At most one LIST response should be returned for each mailbox 2342 name that matches the canonical LIST pattern. Server 2343 implementors must not assume that clients will be able to 2344 assemble mailbox attributes and other information returned in 2345 multiple LIST responses. 2347 2. There are only two reasons for including a matching mailbox name 2348 in the responses to the LIST command (note that the server is 2349 allowed to return unsolicited responses at any time, and such 2350 responses are not governed by this rule): 2352 A. The mailbox name also satisfies the selection criteria. 2354 B. The mailbox name doesn't satisfy the selection criteria, but 2355 it has at least one descendant mailbox name that satisfies 2356 the selection criteria and that doesn't match the canonical 2357 LIST pattern. 2359 For more information on this case, see the CHILDINFO extended 2360 data item described in Section 6.3.9.6. Note that the 2361 CHILDINFO extended data item can only be returned when the 2362 RECURSIVEMATCH selection option is specified. 2364 3. Attributes returned in the same LIST response must be treated 2365 additively. For example, the following response 2367 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2369 means that the "Fruit/Peach" mailbox doesn't exist, but it is 2370 subscribed. 2372 6.3.9.4. Additional LIST-related Requirements on Clients 2374 All clients MUST treat a LIST attribute with a stronger meaning as 2375 implying any attribute that can be inferred from it. (See 2376 Section 7.2.3 for the list of currently defined attributes). For 2377 example, the client must treat the presence of the \NoInferiors 2378 attribute as if the \HasNoChildren attribute was also sent by the 2379 server. 2381 The following table summarizes inference rules. 2383 +--------------------+-------------------+ 2384 | returned attribute | implied attribute | 2385 +--------------------+-------------------+ 2386 | \NoInferiors | \HasNoChildren | 2387 | \NonExistent | \NoSelect | 2388 +--------------------+-------------------+ 2390 6.3.9.5. The CHILDREN Return Option 2392 The CHILDREN return option is simply an indication that the client 2393 wants information about whether or not mailboxes contain children 2394 mailboxes; a server MAY provide it even if the option is not 2395 specified. 2397 Many IMAP4 clients present to the user a hierarchical view of the 2398 mailboxes that a user has access to. Rather than initially 2399 presenting to the user the entire mailbox hierarchy, it is often 2400 preferable to show to the user a collapsed outline list of the 2401 mailbox hierarchy (particularly if there is a large number of 2402 mailboxes). The user can then expand the collapsed outline hierarchy 2403 as needed. It is common to include within the collapsed hierarchy a 2404 visual clue (such as a ''+'') to indicate that there are child 2405 mailboxes under a particular mailbox. When the visual clue is 2406 clicked, the hierarchy list is expanded to show the child mailboxes. 2407 The CHILDREN return option provides a mechanism for a client to 2408 efficiently determine whether a particular mailbox has children, 2409 without issuing a LIST "" * or a LIST "" % for each mailbox name. 2410 The CHILDREN return option defines two new attributes that MUST be 2411 returned within a LIST response: \HasChildren and \HasNoChildren. 2412 Although these attributes MAY be returned in response to any LIST 2413 command, the CHILDREN return option is provided to indicate that the 2414 client particularly wants this information. If the CHILDREN return 2415 option is present, the server MUST return these attributes even if 2416 their computation is expensive. 2418 \HasChildren 2420 The presence of this attribute indicates that the mailbox has 2421 child mailboxes. A server SHOULD NOT set this attribute if 2422 there are child mailboxes and the user does not have permission 2423 to access any of them. In this case, \HasNoChildren SHOULD be 2424 used. In many cases, however, a server may not be able to 2425 efficiently compute whether a user has access to any child 2426 mailbox. Note that even though the \HasChildren attribute for a 2427 mailbox must be correct at the time of processing of the 2428 mailbox, a client must be prepared to deal with a situation when 2429 a mailbox is marked with the \HasChildren attribute, but no 2430 child mailbox appears in the response to the LIST command. This 2431 might happen, for example, due to children mailboxes being 2432 deleted or made inaccessible to the user (using access control) 2433 by another client before the server is able to list them. 2435 \HasNoChildren 2437 The presence of this attribute indicates that the mailbox has NO 2438 child mailboxes that are accessible to the currently 2439 authenticated user. 2441 It is an error for the server to return both a \HasChildren and a 2442 \HasNoChildren attribute in the same LIST response. 2444 Note: the \HasNoChildren attribute should not be confused with the 2445 the \NoInferiors attribute, which indicates that no child mailboxes 2446 exist now and none can be created in the future. 2448 6.3.9.6. CHILDINFO Extended Data Item 2450 The CHILDINFO extended data item MUST NOT be returned unless the 2451 client has specified the RECURSIVEMATCH selection option. 2453 The CHILDINFO extended data item in a LIST response describes the 2454 selection criteria that has caused it to be returned and indicates 2455 that the mailbox has at least one descendant mailbox that matches the 2456 selection criteria. 2458 Note: Some servers allow for mailboxes to exist without requiring 2459 their parent to exist. For example, a mailbox "Customers/ABC" can 2460 exist while the mailbox "Customers" does not. As CHILDINFO extended 2461 data item is not allowed if the RECURSIVEMATCH selection option is 2462 not specified, such servers SHOULD use the "\NonExistent 2463 \HasChildren" attribute pair to signal to the client that there is a 2464 descendant mailbox that matches the selection criteria. See example 2465 11 in Section 6.3.9.8. 2467 The returned selection criteria allow the client to distinguish a 2468 solicited response from an unsolicited one, as well as to distinguish 2469 among solicited responses caused by multiple pipelined LIST commands 2470 that specify different criteria. 2472 Servers SHOULD ONLY return a non-matching mailbox name along with 2473 CHILDINFO if at least one matching child is not also being returned. 2474 That is, servers SHOULD suppress redundant CHILDINFO responses. 2476 Examples 8 and 10 in Section 6.3.9.8 demonstrate the difference 2477 between present CHILDINFO extended data item and the "\HasChildren" 2478 attribute. 2480 The following table summarizes interaction between the "\NonExistent" 2481 attribute and CHILDINFO (the first column indicates whether the 2482 parent mailbox exists): 2484 +--------+-------------+------------------+-------------------------+ 2485 | exists | meets the | has a child that | returned | 2486 | | selection | meets the | IMAP4rev2/LIST-EXTENDED | 2487 | | criteria | selection | attributes and | 2488 | | | criteria | CHILDINFO | 2489 +--------+-------------+------------------+-------------------------+ 2490 | no | no | no | no LIST response | 2491 | | | | returned | 2492 | yes | no | no | no LIST response | 2493 | | | | returned | 2494 | no | yes | no | (\NonExistent ) | 2495 | yes | yes | no | () | 2496 | no | no | yes | (\NonExistent) + | 2497 | | | | CHILDINFO | 2498 | yes | no | yes | () + CHILDINFO | 2499 | no | yes | yes | (\NonExistent ) + | 2500 | | | | CHILDINFO | 2501 | yes | yes | yes | () + CHILDINFO | 2502 +--------+-------------+------------------+-------------------------+ 2504 where is one or more attributes that correspond to the 2505 selection criteria; for example, for the SUBSCRIBED option the 2506 is \Subscribed. 2508 6.3.9.7. OLDNAME Extended Data Item 2510 The OLDNAME extended data item is included when a mailbox name is 2511 created (with CREATE command), renamed (with RENAME command) or 2512 deleted (with DELETE command). (When a mailbox is deleted the 2513 "\NonExistent" attribute is also included.) IMAP extensions can 2514 specify other conditions when OLDNAME extended data item should be 2515 included. 2517 If the server allows de-normalized mailbox names (see Section 5.1) in 2518 SELECT/EXAMINE, CREATE, RENAME or DELETE, it SHOULD return an 2519 unsolicited LIST response that includes OLDNAME extended data item, 2520 whenever the supplied mailbox name differs from the resulting 2521 normalized mailbox name. From the client point of view this is 2522 indistinguishable from another user renaming of deleting the mailbox, 2523 as specified in the previous paragraph. 2525 A deleted mailbox can be announced like this: 2527 S: * LIST (\NonExistent) "." "INBOX.DeletedMailbox" 2529 Example of a renamed mailbox: 2531 S: * LIST () "/" "NewMailbox" ("OLDNAME" ("OldMailbox")) 2533 6.3.9.8. LIST Command Examples 2535 This example shows some uses of the basic LIST command: 2537 Example: C: A101 LIST "" "" 2538 S: * LIST (\Noselect) "/" "" 2539 S: A101 OK LIST Completed 2540 C: A102 LIST #news.comp.mail.misc "" 2541 S: * LIST (\Noselect) "." #news. 2542 S: A102 OK LIST Completed 2543 C: A103 LIST /usr/staff/jones "" 2544 S: * LIST (\Noselect) "/" / 2545 S: A103 OK LIST Completed 2546 C: A202 LIST ~/Mail/ % 2547 S: * LIST (\Noselect) "/" ~/Mail/foo 2548 S: * LIST () "/" ~/Mail/meetings 2549 S: A202 OK LIST completed 2551 Extended examples: 2553 1: The first example shows the complete local hierarchy that will 2554 be used for the other examples. 2556 C: A01 LIST "" "*" 2557 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2558 S: * LIST () "/" "Fruit" 2559 S: * LIST () "/" "Fruit/Apple" 2560 S: * LIST () "/" "Fruit/Banana" 2561 S: * LIST () "/" "Tofu" 2562 S: * LIST () "/" "Vegetable" 2563 S: * LIST () "/" "Vegetable/Broccoli" 2564 S: * LIST () "/" "Vegetable/Corn" 2565 S: A01 OK done 2567 2: In the next example, we will see the subscribed mailboxes. This 2568 is similar to, but not equivalent with now deprecated, (see [RFC3501] for more details on LSUB command). Note 2570 that the mailbox called "Fruit/Peach" is subscribed to, but does 2571 not actually exist (perhaps it was deleted while still 2572 subscribed). The "Fruit" mailbox is not subscribed to, but it 2573 has two subscribed children. The "Vegetable" mailbox is 2574 subscribed and has two children; one of them is subscribed as 2575 well. 2577 C: A02 LIST (SUBSCRIBED) "" "*" 2578 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2579 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2580 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2581 S: * LIST (\Subscribed) "/" "Vegetable" 2582 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2583 S: A02 OK done 2585 3: The next example shows the use of the CHILDREN option. The 2586 client, without having to list the second level of hierarchy, 2587 now knows which of the top-level mailboxes have submailboxes 2588 (children) and which do not. Note that it's not necessary for 2589 the server to return the \HasNoChildren attribute for the inbox, 2590 because the \NoInferiors attribute already implies that, and has 2591 a stronger meaning. 2593 C: A03 LIST () "" "%" RETURN (CHILDREN) 2594 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2595 S: * LIST (\HasChildren) "/" "Fruit" 2596 S: * LIST (\HasNoChildren) "/" "Tofu" 2597 S: * LIST (\HasChildren) "/" "Vegetable" 2598 S: A03 OK done 2600 4: In this example, we see more mailboxes that reside on another 2601 server. This is similar to the command . 2603 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 2604 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2605 S: * LIST (\HasChildren) "/" "Fruit" 2606 S: * LIST (\HasNoChildren) "/" "Tofu" 2607 S: * LIST (\HasChildren) "/" "Vegetable" 2608 S: * LIST (\Remote) "/" "Bread" 2609 S: * LIST (\HasChildren \Remote) "/" "Meat" 2610 S: A04 OK done 2612 5: The following example also requests the server to include 2613 mailboxes that reside on another server. The server returns 2614 information about all mailboxes that are subscribed. This is 2615 similar to the command (see [RFC2193] for more 2616 details on RLSUB). We also see the use of two selection 2617 options. 2619 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 2620 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2621 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2622 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2623 S: * LIST (\Subscribed) "/" "Vegetable" 2624 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2625 S: * LIST (\Remote \Subscribed) "/" "Bread" 2626 S: A05 OK done 2628 6: The following example requests the server to include mailboxes 2629 that reside on another server. The server is asked to return 2630 subscription information for all returned mailboxes. This is 2631 different from the example above. 2633 Note that the output of this command is not a superset of the 2634 output in the previous example, as it doesn't include LIST 2635 response for the non-existent "Fruit/Peach". 2637 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 2638 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2639 S: * LIST () "/" "Fruit" 2640 S: * LIST () "/" "Fruit/Apple" 2641 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2642 S: * LIST () "/" "Tofu" 2643 S: * LIST (\Subscribed) "/" "Vegetable" 2644 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2645 S: * LIST () "/" "Vegetable/Corn" 2646 S: * LIST (\Remote \Subscribed) "/" "Bread" 2647 S: * LIST (\Remote) "/" "Meat" 2648 S: A06 OK done 2650 7: The following example demonstrates the difference between the 2651 \HasChildren attribute and the CHILDINFO extended data item. 2653 Let's assume there is the following hierarchy: 2655 C: C01 LIST "" "*" 2656 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2657 S: * LIST () "/" "Foo" 2658 S: * LIST () "/" "Foo/Bar" 2659 S: * LIST () "/" "Foo/Baz" 2660 S: * LIST () "/" "Moo" 2661 S: C01 OK done 2663 If the client asks RETURN (CHILDREN), it will get this: 2665 C: CA3 LIST "" "%" RETURN (CHILDREN) 2666 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2667 S: * LIST (\HasChildren) "/" "Foo" 2668 S: * LIST (\HasNoChildren) "/" "Moo" 2669 S: CA3 OK done 2671 A) Let's also assume that the mailbox "Foo/Baz" is the only 2672 subscribed mailbox. Then we get this result: 2674 C: C02 LIST (SUBSCRIBED) "" "*" 2675 S: * LIST (\Subscribed) "/" "Foo/Baz" 2676 S: C02 OK done 2678 Now, if the client issues , the server 2679 will return no mailboxes (as the mailboxes "Moo", "Foo", and 2680 "Inbox" are NOT subscribed). However, if the client issues 2681 this: 2683 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2684 S: * LIST () "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2685 S: C04 OK done 2687 (i.e., the mailbox "Foo" is not subscribed, but it has a child 2688 that is.) 2690 A1) If the mailbox "Foo" had also been subscribed, the last 2691 command would return this: 2693 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2694 S: * LIST (\Subscribed) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2695 S: C04 OK done 2697 or even this: 2699 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2700 S: * LIST (\Subscribed \HasChildren) "/" "Foo" ("CHILDINFO" 2701 ("SUBSCRIBED")) 2702 S: C04 OK done 2704 A2) If we assume instead that the mailbox "Foo" is not part of 2705 the original hierarchy and is not subscribed, the last command 2706 will give this result: 2708 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2709 S: * LIST (\NonExistent) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2710 S: C04 OK done 2711 B) Now, let's assume that no mailbox is subscribed. In this 2712 case, the command will 2713 return no responses, as there are no subscribed children (even 2714 though "Foo" has children). 2716 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 2717 are subscribed. In that case, we see this result: 2719 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 2720 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 2721 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 2722 S: C04 OK done 2724 (which means that the mailbox "Foo" has children, but none of 2725 them is subscribed). 2727 8: The following example demonstrates that the CHILDINFO extended 2728 data item is returned whether or not children mailboxes match 2729 the canonical LIST pattern. 2731 Let's assume there is the following hierarchy: 2733 C: D01 LIST "" "*" 2734 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2735 S: * LIST () "/" "foo2" 2736 S: * LIST () "/" "foo2/bar1" 2737 S: * LIST () "/" "foo2/bar2" 2738 S: * LIST () "/" "baz2" 2739 S: * LIST () "/" "baz2/bar2" 2740 S: * LIST () "/" "baz2/bar22" 2741 S: * LIST () "/" "baz2/bar222" 2742 S: * LIST () "/" "eps2" 2743 S: * LIST () "/" "eps2/mamba" 2744 S: * LIST () "/" "qux2/bar2" 2745 S: D01 OK done 2747 And that the following mailboxes are subscribed: 2749 C: D02 LIST (SUBSCRIBED) "" "*" 2750 S: * LIST (\Subscribed) "/" "foo2/bar1" 2751 S: * LIST (\Subscribed) "/" "foo2/bar2" 2752 S: * LIST (\Subscribed) "/" "baz2/bar2" 2753 S: * LIST (\Subscribed) "/" "baz2/bar22" 2754 S: * LIST (\Subscribed) "/" "baz2/bar222" 2755 S: * LIST (\Subscribed) "/" "eps2" 2756 S: * LIST (\Subscribed) "/" "eps2/mamba" 2757 S: * LIST (\Subscribed) "/" "qux2/bar2" 2758 S: D02 OK done 2759 The client issues the following command first: 2761 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 2762 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2763 S: * LIST (\Subscribed) "/" "foo2/bar2" 2764 S: * LIST (\Subscribed) "/" "baz2/bar2" 2765 S: * LIST (\Subscribed) "/" "baz2/bar22" 2766 S: * LIST (\Subscribed) "/" "baz2/bar222" 2767 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2768 S: * LIST (\Subscribed) "/" "qux2/bar2" 2769 S: D03 OK done 2771 and the server may also include (but this would violate a SHOULD 2772 NOT in Section 3.5, because CHILDINFO is redundant) 2774 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2775 S: * LIST (\NonExistent) "/" "qux2" ("CHILDINFO" ("SUBSCRIBED")) 2777 The CHILDINFO extended data item is returned for mailboxes 2778 "foo2", "baz2", and "eps2", because all of them have subscribed 2779 children, even though for the mailbox "foo2" only one of the two 2780 subscribed children matches the pattern, for the mailbox "baz2" 2781 all the subscribed children match the pattern, and for the 2782 mailbox "eps2" none of the subscribed children matches the 2783 pattern. 2785 Note that if the client issues 2787 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 2788 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2789 S: * LIST (\Subscribed) "/" "foo2/bar1" 2790 S: * LIST (\Subscribed) "/" "foo2/bar2" 2791 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2792 S: * LIST (\Subscribed) "/" "baz2/bar2" 2793 S: * LIST (\Subscribed) "/" "baz2/bar22" 2794 S: * LIST (\Subscribed) "/" "baz2/bar222" 2795 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2796 S: * LIST (\Subscribed) "/" "eps2/mamba" 2797 S: * LIST (\Subscribed) "/" "qux2/bar2" 2798 S: D03 OK done 2800 The LIST responses for mailboxes "foo2", "baz2", and "eps2" 2801 still have the CHILDINFO extended data item, even though this 2802 information is redundant and the client can determine it by 2803 itself. 2805 9: The following example shows usage of extended syntax for mailbox 2806 pattern. It also demonstrates that the presence of the 2807 CHILDINFO extended data item doesn't necessarily imply 2808 \HasChildren. 2810 C: a1 LIST "" ("foo") 2811 S: * LIST () "/" foo 2812 S: a1 OK done 2814 C: a2 LIST (SUBSCRIBED) "" "foo/*" 2815 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 2816 S: a2 OK done 2818 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN (CHILDREN) 2819 S: * LIST (\HasNoChildren) "/" foo ("CHILDINFO" ("SUBSCRIBED")) 2820 S: a3 OK done 2822 10: The following example shows how a server that supports missing 2823 mailbox hierarchy elements can signal to a client that didn't 2824 specify the RECURSIVEMATCH selection option that there is a 2825 child mailbox that matches the selection criteria. 2827 C: a1 LIST (REMOTE) "" * 2828 S: * LIST () "/" music/rock 2829 S: * LIST (\Remote) "/" also/jazz 2830 S: a1 OK done 2832 C: a2 LIST () "" % 2833 S: * LIST (\NonExistent \HasChildren) "/" music 2834 S: a2 OK done 2836 C: a3 LIST (REMOTE) "" % 2837 S: * LIST (\NonExistent \HasChildren) "/" music 2838 S: * LIST (\NonExistent \HasChildren) "/" also 2839 S: a3 OK done 2841 C: a3.1 LIST "" (% music/rock) 2842 S: * LIST () "/" music/rock 2843 S: a3.1 OK done 2845 Because "music/rock" is the only mailbox under "music", there's 2846 no need for the server to also return "music". However clients 2847 must handle both cases. 2849 11: The following examples show use of STATUS return option. 2851 C: A01 LIST "" % RETURN (STATUS (MESSAGES UNSEEN)) 2852 S: * LIST () "." "INBOX" 2853 S: * STATUS "INBOX" (MESSAGES 17 UNSEEN 16) 2854 S: * LIST () "." "foo" 2855 S: * STATUS "foo" (MESSAGES 30 UNSEEN 29) 2856 S: * LIST (\NoSelect) "." "bar" 2857 S: A01 OK List completed. 2859 The "bar" mailbox isn't selectable, so it has no STATUS reply. 2861 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (STATUS 2862 (MESSAGES)) 2863 S: * LIST (\Subscribed) "." "INBOX" 2864 S: * STATUS "INBOX" (MESSAGES 17) 2865 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED")) 2866 S: A02 OK List completed. 2868 The LIST reply for "foo" is returned because it has matching 2869 children, but no STATUS reply is returned because "foo" itself 2870 doesn't match the selection criteria. 2872 6.3.10. NAMESPACE Command 2874 Arguments: none 2876 Responses: REQUIRED untagged responses: NAMESPACE 2878 Result: OK - command completed 2879 NO - Can't complete the command 2880 BAD - arguments invalid 2882 The NAMESPACE command causes a single ungagged NAMESPACE response to 2883 be returned. The untagged NAMESPACE response contains the prefix and 2884 hierarchy delimiter to the server's Personal Namespace(s), Other 2885 Users' Namespace(s), and Shared Namespace(s) that the server wishes 2886 to expose. The response will contain a NIL for any namespace class 2887 that is not available. The Namespace-Response-Extensions ABNF non 2888 terminal is defined for extensibility and MAY be included in the 2889 NAMESPACE response. 2891 Example 1: 2893 In this example a server supports a single personal namespace. No 2894 leading prefix is used on personal mailboxes and "/" is the hierarchy 2895 delimiter. 2897 C: A001 NAMESPACE 2898 S: * NAMESPACE (("" "/")) NIL NIL 2899 S: A001 OK NAMESPACE command completed 2901 Example 2: 2903 A user logged on anonymously to a server. No personal mailboxes are 2904 associated with the anonymous user and the user does not have access 2905 to the Other Users' Namespace. No prefix is required to access 2906 shared mailboxes and the hierarchy delimiter is "." 2908 C: A001 NAMESPACE 2909 S: * NAMESPACE NIL NIL (("" ".")) 2910 S: A001 OK NAMESPACE command completed 2912 Example 3: 2914 A server that contains a Personal Namespace and a single Shared 2915 Namespace. 2917 C: A001 NAMESPACE 2918 S: * NAMESPACE (("" "/")) NIL (("Public Folders/" "/")) 2919 S: A001 OK NAMESPACE command completed 2921 Example 4: 2923 A server that contains a Personal Namespace, Other Users' Namespace 2924 and multiple Shared Namespaces. Note that the hierarchy delimiter 2925 used within each namespace can be different. 2927 C: A001 NAMESPACE 2928 S: * NAMESPACE (("" "/")) (("~" "/")) (("#shared/" "/") 2929 ("#public/" "/")("#ftp/" "/")("#news." ".")) 2930 S: A001 OK NAMESPACE command completed 2932 The prefix string allows a client to do things such as automatically 2933 creating personal mailboxes or LISTing all available mailboxes within 2934 a namespace. 2936 Example 5: 2938 A server that supports only the Personal Namespace, with a leading 2939 prefix of INBOX to personal mailboxes and a hierarchy delimiter of 2940 "." 2941 C: A001 NAMESPACE 2942 S: * NAMESPACE (("INBOX." ".")) NIL NIL 2943 S: A001 OK NAMESPACE command completed 2945 < Automatically create a mailbox to store sent items.> 2947 C: A002 CREATE "INBOX.Sent Mail" 2948 S: A002 OK CREATE command completed 2950 Although typically a server will support only a single Personal 2951 Namespace, and a single Other User's Namespace, circumstances exist 2952 where there MAY be multiples of these, and a client MUST be prepared 2953 for them. If a client is configured such that it is required to 2954 create a certain mailbox, there can be circumstances where it is 2955 unclear which Personal Namespaces it should create the mailbox in. 2956 In these situations a client SHOULD let the user select which 2957 namespaces to create the mailbox in or just use the first personal 2958 namespace. 2960 Example 6: 2962 In this example, a server supports 2 Personal Namespaces. In 2963 addition to the regular Personal Namespace, the user has an 2964 additional personal namespace to allow access to mailboxes in an MH 2965 format mailstore. 2967 The client is configured to save a copy of all mail sent by the user 2968 into a mailbox called 'Sent Mail'. Furthermore, after a message is 2969 deleted from a mailbox, the client is configured to move that message 2970 to a mailbox called 'Deleted Items'. 2972 Note that this example demonstrates how some extension flags can be 2973 passed to further describe the #mh namespace. 2975 C: A001 NAMESPACE 2976 S: * NAMESPACE (("" "/")("#mh/" "/" "X-PARAM" 2977 ("FLAG1" "FLAG2"))) NIL NIL 2978 S: A001 OK NAMESPACE command completed 2980 < It is desired to keep only one copy of sent mail. 2981 It is unclear which Personal Namespace the client 2982 should use to create the 'Sent Mail' mailbox. 2983 The user is prompted to select a namespace and only 2984 one 'Sent Mail' mailbox is created. > 2986 C: A002 CREATE "Sent Mail" 2987 S: A002 OK CREATE command completed 2989 < The client is designed so that it keeps two 2990 'Deleted Items' mailboxes, one for each namespace. > 2992 C: A003 CREATE "Delete Items" 2993 S: A003 OK CREATE command completed 2995 C: A004 CREATE "#mh/Deleted Items" 2996 S: A004 OK CREATE command completed 2998 The next level of hierarchy following the Other Users' Namespace 2999 prefix SHOULD consist of , where is a user name 3000 as per the LOGIN or AUTHENTICATE command. 3002 A client can construct a LIST command by appending a "%" to the Other 3003 Users' Namespace prefix to discover the Personal Namespaces of other 3004 users that are available to the currently authenticated user. 3006 In response to such a LIST command, a server SHOULD NOT return user 3007 names that have not granted access to their personal mailboxes to the 3008 user in question. 3010 A server MAY return a LIST response containing only the names of 3011 users that have explicitly granted access to the user in question. 3013 Alternatively, a server MAY return NO to such a LIST command, 3014 requiring that a user name be included with the Other Users' 3015 Namespace prefix before listing any other user's mailboxes. 3017 Example 7: 3019 A server that supports providing a list of other user's mailboxes 3020 that are accessible to the currently logged on user. 3022 C: A001 NAMESPACE 3023 S: * NAMESPACE (("" "/")) (("Other Users/" "/")) NIL 3024 S: A001 OK NAMESPACE command completed 3026 C: A002 LIST "" "Other Users/%" 3027 S: * LIST () "/" "Other Users/Mike" 3028 S: * LIST () "/" "Other Users/Karen" 3029 S: * LIST () "/" "Other Users/Matthew" 3030 S: * LIST () "/" "Other Users/Tesa" 3031 S: A002 OK LIST command completed 3033 Example 8: 3035 A server that does not support providing a list of other user's 3036 mailboxes that are accessible to the currently logged on user. The 3037 mailboxes are listable if the client includes the name of the other 3038 user with the Other Users' Namespace prefix. 3040 C: A001 NAMESPACE 3041 S: * NAMESPACE (("" "/")) (("#Users/" "/")) NIL 3042 S: A001 OK NAMESPACE command completed 3044 < In this example, the currently logged on user has access to 3045 the Personal Namespace of user Mike, but the server chose to 3046 suppress this information in the LIST response. However, 3047 by appending the user name Mike (received through user input) 3048 to the Other Users' Namespace prefix, the client is able 3049 to get a listing of the personal mailboxes of user Mike. > 3051 C: A002 LIST "" "#Users/%" 3052 S: A002 NO The requested item could not be found. 3054 C: A003 LIST "" "#Users/Mike/%" 3055 S: * LIST () "/" "#Users/Mike/INBOX" 3056 S: * LIST () "/" "#Users/Mike/Foo" 3057 S: A003 OK LIST command completed. 3059 A prefix string might not contain a hierarchy delimiter, because in 3060 some cases it is not needed as part of the prefix. 3062 Example 9: 3064 A server that allows access to the Other Users' Namespace by 3065 prefixing the others' mailboxes with a '~' followed by , 3066 where is a user name as per the LOGIN or AUTHENTICATE 3067 command. 3069 C: A001 NAMESPACE 3070 S: * NAMESPACE (("" "/")) (("~" "/")) NIL 3071 S: A001 OK NAMESPACE command completed 3073 < List the mailboxes for user mark > 3075 C: A002 LIST "" "~mark/%" 3076 S: * LIST () "/" "~mark/INBOX" 3077 S: * LIST () "/" "~mark/foo" 3078 S: A002 OK LIST command completed 3080 6.3.11. STATUS Command 3082 Arguments: mailbox name 3083 status data item names 3085 Responses: REQUIRED untagged responses: STATUS 3087 Result: OK - status completed 3088 NO - status failure: no status for that name 3089 BAD - command unknown or arguments invalid 3091 The STATUS command requests the status of the indicated mailbox. It 3092 does not change the currently selected mailbox, nor does it affect 3093 the state of any messages in the queried mailbox. 3095 The STATUS command provides an alternative to opening a second 3096 IMAP4rev2 connection and doing an EXAMINE command on a mailbox to 3097 query that mailbox's status without deselecting the current mailbox 3098 in the first IMAP4rev2 connection. 3100 Unlike the LIST command, the STATUS command is not guaranteed to be 3101 fast in its response. Under certain circumstances, it can be quite 3102 slow. In some implementations, the server is obliged to open the 3103 mailbox read-only internally to obtain certain status information. 3104 Also unlike the LIST command, the STATUS command does not accept 3105 wildcards. 3107 Note: The STATUS command is intended to access the status of 3108 mailboxes other than the currently selected mailbox. Because the 3109 STATUS command can cause the mailbox to be opened internally, and 3110 because this information is available by other means on the 3111 selected mailbox, the STATUS command SHOULD NOT be used on the 3112 currently selected mailbox. However, servers MUST be able to 3113 execute STATUS command on the selected mailbox. (This might also 3114 implicitly happen when STATUS return option is used in a LIST 3115 command). 3117 The STATUS command MUST NOT be used as a "check for new messages 3118 in the selected mailbox" operation (refer to sections Section 7, 3119 Section 7.3.1 for more information about the proper method for new 3120 message checking). 3122 STATUS SIZE (see below) can take a significant amount of time, 3123 depending upon server implementation. Clients should use STATUS 3124 SIZE cautiously. 3126 The currently defined status data items that can be requested are: 3128 MESSAGES The number of messages in the mailbox. 3130 UIDNEXT The next unique identifier value of the mailbox. Refer to 3131 Section 2.3.1.1 for more information. 3133 UIDVALIDITY The unique identifier validity value of the mailbox. 3134 Refer to Section 2.3.1.1 for more information. 3136 UNSEEN The number of messages which do not have the \Seen flag set. 3138 DELETED The number of messages which have the \Deleted flag set. 3140 SIZE The total size of the mailbox in octets. This is not strictly 3141 required to be an exact value, but it MUST be equal to or greater 3142 than the sum of the values of the RFC822.SIZE FETCH message data 3143 items (see Section 6.4.5) of all messages in the mailbox. 3145 Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES) 3146 S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 3147 S: A042 OK STATUS completed 3149 6.3.12. APPEND Command 3151 Arguments: mailbox name 3152 OPTIONAL flag parenthesized list 3153 OPTIONAL date/time string 3154 message literal 3156 Responses: OPTIONAL untagged response: LIST 3158 Result: OK - append completed 3159 NO - append error: can't append to that mailbox, error 3160 in flags or date/time or message text 3161 BAD - command unknown or arguments invalid 3163 The APPEND command appends the literal argument as a new message to 3164 the end of the specified destination mailbox. This argument SHOULD 3165 be in the format of an [RFC-5322] or [I18N-HDRS] message. 8-bit 3166 characters are permitted in the message. A server implementation 3167 that is unable to preserve 8-bit data properly MUST be able to 3168 reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB] 3169 content transfer encoding. 3171 Note: There may be exceptions, e.g., draft messages, in which 3172 required [RFC-5322] header lines are omitted in the message 3173 literal argument to APPEND. The full implications of doing so 3174 must be understood and carefully weighed. 3176 If a flag parenthesized list is specified, the flags SHOULD be set in 3177 the resulting message; otherwise, the flag list of the resulting 3178 message is set to empty by default. 3180 If a date-time is specified, the internal date SHOULD be set in the 3181 resulting message; otherwise, the internal date of the resulting 3182 message is set to the current date and time by default. 3184 If the append is unsuccessful for any reason, the mailbox MUST be 3185 restored to its state before the APPEND attempt (other than possibly 3186 keeping the changed mailbox's UIDNEXT value); no partial appending is 3187 permitted. 3189 If the destination mailbox does not exist, a server MUST return an 3190 error, and MUST NOT automatically create the mailbox. Unless it is 3191 certain that the destination mailbox can not be created, the server 3192 MUST send the response code "[TRYCREATE]" as the prefix of the text 3193 of the tagged NO response. This gives a hint to the client that it 3194 can attempt a CREATE command and retry the APPEND if the CREATE is 3195 successful. 3197 On successful completion of an APPEND, the server SHOULD return an 3198 APPENDUID response code (see Section 7.1). 3200 In the case of a mailbox that has permissions set so that the client 3201 can APPEND to the mailbox, but not SELECT or EXAMINE it, the server 3202 SHOULD NOT send an APPENDUID response code as it would disclose 3203 information about the mailbox. 3205 In the case of a mailbox that has UIDNOTSTICKY status (see 3206 Section 7.1), the server MAY omit the APPENDUID response code as it 3207 is not meaningful. 3209 If the server does not return the APPENDUID response codes, the 3210 client can discover this information by selecting the destination 3211 mailbox. The location of messages placed in the destination mailbox 3212 by APPEND can be determined by using FETCH and/or SEARCH commands 3213 (e.g., for Message-ID or some unique marker placed in the message in 3214 an APPEND). 3216 If the mailbox is currently selected, the normal new message actions 3217 SHOULD occur. Specifically, the server SHOULD notify the client 3218 immediately via an untagged EXISTS response. If the server does not 3219 do so, the client MAY issue a NOOP command after one or more APPEND 3220 commands. 3222 If the server decides to convert (normalize) the mailbox name, it 3223 SHOULD return an untagged LIST with OLDNAME extended data item, with 3224 the OLDNAME value being the supplied mailbox name and the name 3225 parameter being the normalized mailbox name. (See Section 6.3.9.7 3226 for more details.) 3228 Example: C: A003 APPEND saved-messages (\Seen) {310} 3229 S: + Ready for literal data 3230 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3231 C: From: Fred Foobar 3232 C: Subject: afternoon meeting 3233 C: To: mooch@owatagu.siam.edu 3234 C: Message-Id: 3235 C: MIME-Version: 1.0 3236 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3237 C: 3238 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3239 C: 3240 S: A003 OK APPEND completed 3242 Example: C: A003 APPEND saved-messages (\Seen) {297} 3243 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3244 C: From: Fred Foobar 3245 C: Subject: afternoon meeting 3246 C: To: mooch@example.com 3247 C: Message-Id: 3248 C: MIME-Version: 1.0 3249 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3250 C: 3251 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3252 C: 3253 S: A003 OK [APPENDUID 38505 3955] APPEND completed 3254 C: A004 COPY 2:4 meeting 3255 S: A004 OK [COPYUID 38505 304,319:320 3956:3958] Done 3256 C: A005 UID COPY 305:310 meeting 3257 S: A005 OK No matching messages, so nothing copied 3258 C: A006 COPY 2 funny 3259 S: A006 OK Done 3260 C: A007 SELECT funny 3261 S: * 1 EXISTS 3262 S: * OK [UIDVALIDITY 3857529045] Validity session-only 3263 S: * OK [UIDNEXT 2] Predicted next UID 3264 S: * NO [UIDNOTSTICKY] Non-persistent UIDs 3265 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 3266 S: * OK [PERMANENTFLAGS (\Deleted \Seen)] Limited 3267 S: * LIST () "." funny 3268 S: A007 OK [READ-WRITE] SELECT completed 3270 In this example, A003 and A004 demonstrate successful appending and 3271 copying to a mailbox that returns the UIDs assigned to the messages. 3272 A005 is an example in which no messages were copied; this is because 3273 in A003, we see that message 2 had UID 304, and message 3 had UID 3274 319; therefore, UIDs 305 through 310 do not exist (refer to 3275 Section 2.3.1.1 for further explanation). A006 is an example of a 3276 message being copied that did not return a COPYUID; and, as expected, 3277 A007 shows that the mail store containing that mailbox does not 3278 support persistent UIDs. 3280 Note: The APPEND command is not used for message delivery, because 3281 it does not provide a mechanism to transfer [SMTP] envelope 3282 information. 3284 6.3.13. IDLE Command 3286 Arguments: none 3288 Responses: continuation data will be requested; the client sends the 3289 continuation data "DONE" to end the command 3291 Result: OK - IDLE completed after client sent "DONE" 3292 NO - failure: the server will not allow the IDLE command 3293 at this time 3294 BAD - command unknown or arguments invalid 3296 Without the IDLE command a client requires to poll the server for 3297 changes to the selected mailbox (new mail, deletions, flag changes). 3298 It's often more desirable to have the server transmit updates to the 3299 client in real time. This allows a user to see new mail immediately. 3300 The IDLE command allows a client to tell the server that it's ready 3301 to accept such real-time updates. 3303 The IDLE command is sent from the client to the server when the 3304 client is ready to accept unsolicited update messages. The server 3305 requests a response to the IDLE command using the continuation ("+") 3306 response. The IDLE command remains active until the client responds 3307 to the continuation, and as long as an IDLE command is active, the 3308 server is now free to send untagged EXISTS, EXPUNGE, FETCH, and other 3309 responses at any time. If the server choose to send unsolicited 3310 FETCH responses, they MUST include UID FETCH item. 3312 The IDLE command is terminated by the receipt of a "DONE" 3313 continuation from the client; such response satisfies the server's 3314 continuation request. At that point, the server MAY send any 3315 remaining queued untagged responses and then MUST immediately send 3316 the tagged response to the IDLE command and prepare to process other 3317 commands. As for other commands, the processing of any new command 3318 may cause the sending of unsolicited untagged responses, subject to 3319 the ambiguity limitations. The client MUST NOT send a command while 3320 the server is waiting for the DONE, since the server will not be able 3321 to distinguish a command from a continuation. 3323 The server MAY consider a client inactive if it has an IDLE command 3324 running, and if such a server has an inactivity timeout it MAY log 3325 the client off implicitly at the end of its timeout period. Because 3326 of that, clients using IDLE are advised to terminate the IDLE and re- 3327 issue it at least every 29 minutes to avoid being logged off. This 3328 still allows a client to receive immediate mailbox updates even 3329 though it need only "poll" at half hour intervals. 3331 Example: C: A001 SELECT INBOX 3332 S: * FLAGS (\Deleted \Seen \Flagged) 3333 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Flagged)] Limited 3334 S: * 3 EXISTS 3335 S: * OK [UIDVALIDITY 1] 3336 S: * LIST () "/" INBOX 3337 S: A001 OK [READ-WRITE] SELECT completed 3338 C: A002 IDLE 3339 S: + idling 3340 ...time passes; new mail arrives... 3341 S: * 4 EXISTS 3342 C: DONE 3343 S: A002 OK IDLE terminated 3344 ...another client expunges message 2 now... 3345 C: A003 FETCH 4 ALL 3346 S: * 4 FETCH (...) 3347 S: A003 OK FETCH completed 3348 C: A004 IDLE 3349 S: * 2 EXPUNGE 3350 S: * 3 EXISTS 3351 S: + idling 3352 ...time passes; another client expunges message 3... 3353 S: * 3 EXPUNGE 3354 S: * 2 EXISTS 3355 ...time passes; new mail arrives... 3356 S: * 3 EXISTS 3357 C: DONE 3358 S: A004 OK IDLE terminated 3359 C: A005 FETCH 3 ALL 3360 S: * 3 FETCH (...) 3361 S: A005 OK FETCH completed 3362 C: A006 IDLE 3364 6.4. Client Commands - Selected State 3366 In the selected state, commands that manipulate messages in a mailbox 3367 are permitted. 3369 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 3370 and the authenticated state commands (SELECT, EXAMINE, NAMESPACE, 3371 CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, STATUS, and 3372 APPEND), the following commands are valid in the selected state: 3373 CLOSE, UNSELECT, EXPUNGE, SEARCH, FETCH, STORE, COPY, MOVE, and UID. 3375 6.4.1. CLOSE Command 3377 Arguments: none 3379 Responses: no specific responses for this command 3381 Result: OK - close completed, now in authenticated state 3382 BAD - command unknown or arguments invalid 3384 The CLOSE command permanently removes all messages that have the 3385 \Deleted flag set from the currently selected mailbox, and returns to 3386 the authenticated state from the selected state. No untagged EXPUNGE 3387 responses are sent. 3389 No messages are removed, and no error is given, if the mailbox is 3390 selected by an EXAMINE command or is otherwise selected read-only. 3392 Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT command 3393 MAY be issued without previously issuing a CLOSE command. The 3394 SELECT, EXAMINE, and LOGOUT commands implicitly close the currently 3395 selected mailbox without doing an expunge. However, when many 3396 messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT sequence is 3397 considerably faster than an EXPUNGE-LOGOUT or EXPUNGE-SELECT because 3398 no untagged EXPUNGE responses (which the client would probably 3399 ignore) are sent. 3401 Example: C: A341 CLOSE 3402 S: A341 OK CLOSE completed 3404 6.4.2. UNSELECT Command 3406 Arguments: none 3408 Responses: no specific responses for this command 3410 Result: OK - unselect completed, now in authenticated state 3411 BAD - no mailbox selected, or argument supplied but none 3412 permitted 3414 The UNSELECT command frees server's resources associated with the 3415 selected mailbox and returns the server to the authenticated state. 3416 This command performs the same actions as CLOSE, except that no 3417 messages are permanently removed from the currently selected mailbox. 3419 Example: C: A342 UNSELECT 3420 S: A342 OK Unselect completed 3422 6.4.3. EXPUNGE Command 3424 Arguments: none 3426 Responses: untagged responses: EXPUNGE 3428 Result: OK - expunge completed 3429 NO - expunge failure: can't expunge (e.g., permission 3430 denied) 3431 BAD - command unknown or arguments invalid 3433 The EXPUNGE command permanently removes all messages that have the 3434 \Deleted flag set from the currently selected mailbox. Before 3435 returning an OK to the client, an untagged EXPUNGE response is sent 3436 for each message that is removed. 3438 Example: C: A202 EXPUNGE 3439 S: * 3 EXPUNGE 3440 S: * 3 EXPUNGE 3441 S: * 5 EXPUNGE 3442 S: * 8 EXPUNGE 3443 S: A202 OK EXPUNGE completed 3445 Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag 3446 set. See the description of the EXPUNGE response for further 3447 explanation. 3449 6.4.4. SEARCH Command 3451 Arguments: OPTIONAL result specifier 3452 OPTIONAL [CHARSET] specification 3453 searching criteria (one or more) 3455 Responses: OPTIONAL untagged response: ESEARCH 3457 Result: OK - search completed 3458 NO - search error: can't search that [CHARSET] or 3459 criteria 3460 BAD - command unknown or arguments invalid 3462 The SEARCH command searches the mailbox for messages that match the 3463 given searching criteria. 3465 The SEARCH command may contain result options. Result options 3466 control what kind of information is returned about messages matching 3467 the search criteria in an untagged ESEARCH response. If no result 3468 option is specified or empty list of options is specified "()", ALL 3469 is assumed (see below). The order of individual options is 3470 arbitrary. Individual options may contain parameters enclosed in 3471 parentheses (*). If an option has parameters, they consist of atoms 3472 and/or strings and/or lists in a specific order. Any options not 3473 defined by extensions that the server supports must be rejected with 3474 a BAD response. 3476 (*) - if an option has a mandatory parameter, which can always be 3477 represented as a number or a sequence-set, the option parameter does 3478 not need the enclosing (). See the ABNF for more details. 3480 This document specifies the following result options: 3482 MIN 3484 Return the lowest message number/UID that satisfies the SEARCH 3485 criteria. 3487 If the SEARCH results in no matches, the server MUST NOT 3488 include the MIN result option in the ESEARCH response; however, 3489 it still MUST send the ESEARCH response. 3491 MAX 3493 Return the highest message number/UID that satisfies the SEARCH 3494 criteria. 3496 If the SEARCH results in no matches, the server MUST NOT 3497 include the MAX result option in the ESEARCH response; however, 3498 it still MUST send the ESEARCH response. 3500 ALL 3502 Return all message numbers/UIDs that satisfy the SEARCH 3503 criteria using the sequence-set syntax. Note, the client MUST 3504 NOT assume that messages/UIDs will be listed in any particular 3505 order. 3507 If the SEARCH results in no matches, the server MUST NOT 3508 include the ALL result option in the ESEARCH response; however, 3509 it still MUST send the ESEARCH response. 3511 COUNT Return number of the messages that satisfy the SEARCH 3512 criteria. This result option MUST always be included in the 3513 ESEARCH response. 3515 SAVE 3516 This option tells the server to remember the result of the 3517 SEARCH or UID SEARCH command (as well as any command based on 3518 SEARCH, e.g., SORT and THREAD [RFC5256]>) and store it in an 3519 internal variable that we will reference as the "search result 3520 variable". The client can use the "$" marker to reference the 3521 content of this internal variable. The "$" marker can be used 3522 instead of message sequence or UID sequence in order to 3523 indicate that the server should substitute it with the list of 3524 messages from the search result variable. Thus, the client can 3525 use the result of the latest remembered SEARCH command as a 3526 parameter to another command. See Section 6.4.4.1 for details 3527 on how the value of the search result variable is determined, 3528 how it is affected by other commands executed, and how SAVE 3529 return option interacts with other return options. 3531 In absence of any other SEARCH result option, the SAVE result 3532 option also suppresses any ESEARCH response that would have 3533 been otherwise returned by the SEARCH command. 3535 Note: future extensions to this document can allow servers to return 3536 multiple ESEARCH responses for a single extended SEARCH command. 3537 However all options specified above MUST result in a single ESEARCH 3538 response if used by themselves or in a combination. This guaranty 3539 simplifies processing in IMAP4rev2 clients. Future SEARCH extensions 3540 that relax this restriction will have to describe how results from 3541 multiple ESEARCH responses are to be amalgamated. 3543 Searching criteria consist of one or more search keys. 3545 When multiple keys are specified, the result is the intersection (AND 3546 function) of all the messages that match those keys. For example, 3547 the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers to all 3548 deleted messages from Smith with INTERNALDATE greater than February 3549 1, 1994. A search key can also be a parenthesized list of one or 3550 more search keys (e.g., for use with the OR and NOT keys). 3552 Server implementations MAY exclude [MIME-IMB] body parts with 3553 terminal content media types other than TEXT and MESSAGE from 3554 consideration in SEARCH matching. 3556 The OPTIONAL [CHARSET] specification consists of the word "CHARSET" 3557 followed by a registered [CHARSET] [CHARSET-REG]. It indicates the 3558 [CHARSET] of the strings that appear in the search criteria. 3559 [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in 3560 [RFC-5322]/[MIME-IMB] headers, MUST be decoded before comparing text. 3561 Servers MUST support US-ASCII and UTF-8 charsets; other [CHARSET]s 3562 MAY be supported. Clients SHOULD use UTF-8. Note that if "CHARSET" 3563 is not provided IMAP4rev2 server MUST assume UTF-8, so selecting 3564 CHARSET UTF-8 is redundant. It is permitted for improved 3565 compatibility with existing IMAP4rev1 clients. 3567 If the server does not support the specified [CHARSET], it MUST 3568 return a tagged NO response (not a BAD). This response SHOULD 3569 contain the BADCHARSET response code, which MAY list the [CHARSET]s 3570 supported by the server. 3572 In all search keys that use strings and unless specified otherwise, a 3573 message matches the key if the string is a substring of the 3574 associated text. The matching SHOULD be case-insensitive for 3575 characters within ASCII range. Consider using [IMAP-I18N] for 3576 language-sensitive case-insensitive searching. Note that the empty 3577 string is a substring; this is useful when doing a HEADER search in 3578 order to test for a header field presence in the message. 3580 The defined search keys are as follows. Refer to the Formal Syntax 3581 section for the precise syntactic definitions of the arguments. 3583 Messages with message sequence numbers corresponding 3584 to the specified message sequence number set. 3586 ALL All messages in the mailbox; the default initial key for ANDing. 3588 ANSWERED Messages with the \Answered flag set. 3590 BCC Messages that contain the specified string in the 3591 envelope structure's BCC field. 3593 BEFORE Messages whose internal date (disregarding time and 3594 timezone) is earlier than the specified date. 3596 BODY Messages that contain the specified string in the body 3597 of the message. Unlike TEXT (see below), this doesn't match any 3598 header fields. Servers are allowed to implement flexible matching 3599 for this search key, for example matching "swim" to both "swam" 3600 and "swum" in English language text or only doing full word 3601 matching (where "swim" will not match "swimming"). 3603 CC Messages that contain the specified string in the 3604 envelope structure's CC field. 3606 DELETED Messages with the \Deleted flag set. 3608 DRAFT Messages with the \Draft flag set. 3610 FLAGGED Messages with the \Flagged flag set. 3612 FROM Messages that contain the specified string in the 3613 envelope structure's FROM field. 3615 HEADER Messages that have a header with the 3616 specified field-name (as defined in [RFC-5322]) and that contains 3617 the specified string in the text of the header (what comes after 3618 the colon). If the string to search is zero-length, this matches 3619 all messages that have a header line with the specified field-name 3620 regardless of the contents. Servers should use substring search 3621 for this SEARCH item, as clients can use it for automatic 3622 processing not initiated by end users. For example this can be 3623 used for searching for Message-ID or Content-Type header field 3624 values that need to be exact, or for searches in header fields 3625 that the IMAP server might not know anything about. 3627 KEYWORD Messages with the specified keyword flag set. 3629 LARGER Messages with an [RFC-5322] size larger than the 3630 specified number of octets. 3632 NOT Messages that do not match the specified search 3633 key. 3635 ON Messages whose internal date (disregarding time and 3636 timezone) is within the specified date. 3638 OR Messages that match either search 3639 key. 3641 SEEN Messages that have the \Seen flag set. 3643 SENTBEFORE Messages whose [RFC-5322] Date: header 3644 (disregarding time and timezone) is earlier than the specified 3645 date. 3647 SENTON Messages whose [RFC-5322] Date: header (disregarding 3648 time and timezone) is within the specified date. 3650 SENTSINCE Messages whose [RFC-5322] Date: header 3651 (disregarding time and timezone) is within or later than the 3652 specified date. 3654 SINCE Messages whose internal date (disregarding time and 3655 timezone) is within or later than the specified date. 3657 SMALLER Messages with an [RFC-5322] size smaller than the 3658 specified number of octets. 3660 SUBJECT Messages that contain the specified string in the 3661 envelope structure's SUBJECT field. 3663 TEXT Messages that contain the specified string in the 3664 header (including MIME header fields) or body of the message. 3665 Servers are allowed to implement flexible matching for this search 3666 key, for example matching "swim" to both "swam" and "swum" in 3667 English language text or only doing full word matching (where 3668 "swim" will not match "swimming"). 3670 TO Messages that contain the specified string in the 3671 envelope structure's TO field. 3673 UID Messages with unique identifiers corresponding to 3674 the specified unique identifier set. Sequence set ranges are 3675 permitted. 3677 UNANSWERED Messages that do not have the \Answered flag set. 3679 UNDELETED Messages that do not have the \Deleted flag set. 3681 UNDRAFT Messages that do not have the \Draft flag set. 3683 UNFLAGGED Messages that do not have the \Flagged flag set. 3685 UNKEYWORD Messages that do not have the specified keyword 3686 flag set. 3688 UNSEEN Messages that do not have the \Seen flag set. 3690 Example: C: A282 SEARCH RETURN (MIN COUNT) FLAGGED 3691 SINCE 1-Feb-1994 NOT FROM "Smith" 3692 S: * ESEARCH (TAG "A282") MIN 2 COUNT 3 3693 S: A282 OK SEARCH completed 3695 Example: C: A283 SEARCH RETURN () FLAGGED 3696 SINCE 1-Feb-1994 NOT FROM "Smith" 3697 S: * ESEARCH (TAG "A283") ALL 2,10:11 3698 S: A283 OK SEARCH completed 3700 Example: C: A284 SEARCH TEXT "string not in mailbox" 3701 S: * ESEARCH (TAG "A284") 3702 S: A284 OK SEARCH completed 3703 C: A285 SEARCH CHARSET UTF-8 TEXT {6} 3704 S: + Ready for literal text 3705 C: XXXXXX 3706 S: * ESEARCH (TAG "A285") ALL 43 3707 S: A285 OK SEARCH completed 3709 Note: Since this document is restricted to 7-bit ASCII text, it is 3710 not possible to show actual UTF-8 data. The "XXXXXX" is a 3711 placeholder for what would be 6 octets of 8-bit data in an actual 3712 transaction. 3714 The following example demonstrates finding the first unseen message 3715 in the mailbox: 3717 Example: C: A284 SEARCH RETURN (MIN) UNSEEN 3718 S: * ESEARCH (TAG "A284") MIN 4 3719 S: A284 OK SEARCH completed 3721 The following example demonstrates that if the ESEARCH UID indicator 3722 is present, all data in the ESEARCH response is referring to UIDs; 3723 for example, the MIN result specifier will be followed by a UID. 3725 Example: C: A285 UID SEARCH RETURN (MIN MAX) 1:5000 3726 S: * ESEARCH (TAG "A285") UID MIN 7 MAX 3800 3727 S: A285 OK SEARCH completed 3729 The following example demonstrates returning the number of deleted 3730 messages: 3732 Example: C: A286 SEARCH RETURN (COUNT) DELETED 3733 S: * ESEARCH (TAG "A286") COUNT 15 3734 S: A286 OK SEARCH completed 3736 6.4.4.1. SAVE result option and SEARCH result variable 3738 Upon successful completion of a SELECT or an EXAMINE command (after 3739 the tagged OK response), the current search result variable is reset 3740 to the empty sequence. 3742 A successful SEARCH command with the SAVE result option sets the 3743 value of the search result variable to the list of messages found in 3744 the SEARCH command. For example, if no messages were found, the 3745 search result variable will contain the empty sequence. 3747 Any of the following SEARCH commands MUST NOT change the search 3748 result variable: 3750 a SEARCH command that caused the server to return the BAD tagged 3751 response, 3753 a SEARCH command with no SAVE result option that caused the server 3754 to return NO tagged response, 3756 a successful SEARCH command with no SAVE result option. 3758 A SEARCH command with the SAVE result option that caused the server 3759 to return the NO tagged response sets the value of the search result 3760 variable to the empty sequence. 3762 When a message listed in the search result variable is EXPUNGEd, it 3763 is automatically removed from the list. Implementors are reminded 3764 that if the server stores the list as a list of message numbers, it 3765 MUST automatically adjust them when notifying the client about 3766 expunged messages, as described in Section 7.4.1. 3768 If the server decides to send a new UIDVALIDITY value while the 3769 mailbox is opened, this causes resetting of the search variable to 3770 the empty sequence. 3772 Note that even if the "$" marker contains the empty sequence of 3773 messages, it must be treated by all commands accepting message sets 3774 as parameters as a valid, but non-matching list of messages. For 3775 example, the "FETCH $" command would return a tagged OK response and 3776 no FETCH responses. See also the Example 5 in Section 6.4.4.4. 3778 The SAVE result option doesn't change whether the server would return 3779 items corresponding to MIN, MAX, ALL, or COUNT result options. 3781 When the SAVE result option is combined with the MIN or MAX result 3782 option, and both ALL and COUNT result options are absent, the 3783 corresponding MIN/MAX is returned (if the search result is not 3784 empty), but the "$" marker would contain a single message as returned 3785 in the MIN/MAX return item. 3787 If the SAVE result option is combined with both MIN and MAX result 3788 options, and both ALL and COUNT result options are absent, the "$" 3789 marker would contain zero, one or two messages as returned in the 3790 MIN/MAX return items. 3792 If the SAVE result option is combined with the ALL and/or COUNT 3793 result option(s), the "$" marker would always contain all messages 3794 found by the SEARCH or UID SEARCH command. 3796 The following table summarizes the additional requirement on ESEARCH 3797 server implementations described in this section. 3799 +------------------------------+--------------------+ 3800 | Combination of Result option | "$" marker value | 3801 +------------------------------+--------------------+ 3802 | SAVE MIN | MIN | 3803 | SAVE MAX | MAX | 3804 | SAVE MIN MAX | MIN & MAX | 3805 | SAVE * [m] | all found messages | 3806 +------------------------------+--------------------+ 3808 where '*' means "ALL" and/or "COUNT", and '[m]' means optional "MIN" 3809 and/or "MAX" 3811 Implementation note: server implementors should note that "$" can 3812 reference IMAP message sequences or UID sequences, depending on the 3813 context where it is used. For example, the "$" marker can be set as 3814 a result of a SEARCH (SAVE) command and used as a parameter to a UID 3815 FETCH command (which accepts a UID sequence, not a message sequence), 3816 or the "$" marker can be set as a result of a UID SEARCH (SAVE) 3817 command and used as a parameter to a FETCH command (which accepts a 3818 message sequence, not a UID sequence). Server implementations need 3819 to automatically map the "$" marker value to message numbers or UIDs, 3820 depending on context where the "$" marker is used. 3822 6.4.4.2. Multiple Commands in Progress 3824 Use of a SEARCH RETURN (SAVE) command followed by a command using the 3825 "$" marker creates direct dependency between the two commands. As 3826 directed by Section 5.5, a server MUST execute the two commands in 3827 the order they were received. 3829 A client MAY pipeline a SEARCH RETURN (SAVE) command with one or more 3830 command using the "$" marker, as long as this doesn't create an 3831 ambiguity, as described in by Section 5.5. Examples 7-9 in 3832 Section 6.4.4.4 explain this in more details. 3834 6.4.4.3. Refusing to Save Search Results 3836 In some cases, the server MAY refuse to save a SEARCH (SAVE) result, 3837 for example, if an internal limit on the number of saved results is 3838 reached. In this case, the server MUST return a tagged NO response 3839 containing the NOTSAVED response code and set the search result 3840 variable to the empty sequence, as described in Section 6.4.4.1. 3842 6.4.4.4. Examples showing use of SAVE result option 3844 Only in this section: explanatory comments in examples that start 3845 with // are not part of the protocol. 3847 1) The following example demonstrates how the client can use the 3848 result of a SEARCH command to FETCH headers of interesting messages: 3850 Example 1: 3851 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3852 NOT FROM "Smith" 3853 S: A282 OK SEARCH completed, result saved 3854 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3855 S: * 2 FETCH (UID 14 ... 3856 S: * 84 FETCH (UID 100 ... 3857 S: * 882 FETCH (UID 1115 ... 3858 S: A283 OK completed 3860 The client can also pipeline the two commands: 3862 Example 2: 3863 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3864 NOT FROM "Smith" 3865 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3866 S: A282 OK SEARCH completed 3867 S: * 2 FETCH (UID 14 ... 3868 S: * 84 FETCH (UID 100 ... 3869 S: * 882 FETCH (UID 1115 ... 3870 S: A283 OK completed 3872 2) The following example demonstrates that the result of one SEARCH 3873 command can be used as input to another SEARCH command: 3875 Example 3: 3876 C: A300 SEARCH RETURN (SAVE) SINCE 1-Jan-2004 3877 NOT FROM "Smith" 3878 S: A300 OK SEARCH completed 3879 C: A301 UID SEARCH UID $ SMALLER 4096 3880 S: * ESEARCH (TAG "A301") UID ALL 17,900,901 3881 S: A301 OK completed 3883 Note that the second command in Example 3 can be replaced with: 3884 C: A301 UID SEARCH $ SMALLER 4096 3885 and the result of the command would be the same. 3887 3) The following example shows that the "$" marker can be combined 3888 with other message numbers using the OR SEARCH criterion. 3890 Example 4: 3891 C: P282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3892 NOT FROM "Smith" 3893 S: P282 OK SEARCH completed 3894 C: P283 SEARCH CHARSET UTF-8 (OR $ 1,3000:3021) TEXT {8} 3895 C: YYYYYYYY 3896 S: * ESEARCH (TAG "P283") ALL 882,1102,3003,3005:3006 3897 S: P283 OK completed 3899 Note: Since this document format is restricted to 7-bit ASCII text, 3900 it is not possible to show actual UTF-8 data. The "YYYYYYYY" is a 3901 placeholder for what would be 8 octets of 8-bit data in an actual 3902 transaction. 3904 4) The following example demonstrates that a failed SEARCH sets the 3905 search result variable to the empty list. The server doesn't 3906 implement the KOI8-R charset. 3908 Example 5: 3909 C: B282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3910 NOT FROM "Smith" 3911 S: B282 OK SEARCH completed 3912 C: B283 SEARCH RETURN (SAVE) CHARSET KOI8-R 3913 (OR $ 1,3000:3021) TEXT {4} 3914 C: XXXX 3915 S: B283 NO [BADCHARSET UTF-8] KOI8-R is not supported 3916 //After this command the saved result variable contains 3917 //no messages. A client that wants to reissue the B283 3918 //SEARCH command with another CHARSET would have to reissue 3919 //the B282 command as well. One possible workaround for 3920 //this is to include the desired CHARSET parameter 3921 //in the earliest SEARCH RETURN (SAVE) command in a 3922 //sequence of related SEARCH commands, to cause 3923 //the earliest SEARCH in the sequence to fail. 3924 //A better approach might be to always use CHARSET UTF-8 3925 //instead. 3927 Note: Since this document format is restricted to 7-bit ASCII text, 3928 it is not possible to show actual KOI8-R data. The "XXXX" is a 3929 placeholder for what would be 4 octets of 8-bit data in an actual 3930 transaction. 3932 5) The following example demonstrates that it is not an error to use 3933 the "$" marker when it contains no messages. 3935 Example 6: 3936 C: E282 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3937 NOT FROM "Eric" 3938 C: E283 COPY $ "Other Messages" 3939 //The "$" contains no messages 3940 S: E282 OK SEARCH completed 3941 S: E283 OK COPY completed, nothing copied 3943 Example 7: 3944 C: F282 SEARCH RETURN (SAVE) KEYWORD $Junk 3945 C: F283 COPY $ "Junk" 3946 C: F284 STORE $ +FLAGS.Silent (\Deleted) 3947 S: F282 OK SEARCH completed 3948 S: F283 OK COPY completed 3949 S: F284 OK STORE completed 3951 Example 8: 3952 C: G282 SEARCH RETURN (SAVE) KEYWORD $Junk 3953 C: G283 SEARCH RETURN (ALL) SINCE 28-Oct-2006 3954 FROM "Eric" 3955 // The server can execute the two SEARCH commands 3956 // in any order, as they don't have any dependency. 3957 // For example, it may return: 3958 S: * ESEARCH (TAG "G283") ALL 3:15,27,29:103 3959 S: G283 OK SEARCH completed 3960 S: G282 OK SEARCH completed 3962 The following example demonstrates that the result of the second 3963 SEARCH RETURN (SAVE) always overrides the result of the first. 3965 Example 9: 3966 C: H282 SEARCH RETURN (SAVE) KEYWORD $Junk 3967 C: H283 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3968 FROM "Eric" 3969 S: H282 OK SEARCH completed 3970 S: H283 OK SEARCH completed 3971 // At this point "$" would contain results of H283 3973 The following example demonstrates behavioral difference for 3974 different combinations of ESEARCH result options. 3976 Example 10: 3977 C: C282 SEARCH RETURN (ALL) SINCE 12-Feb-2006 3978 NOT FROM "Smith" 3979 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3980 //$ value hasn't changed 3981 S: C282 OK SEARCH completed 3983 C: C283 SEARCH RETURN (ALL SAVE) SINCE 12-Feb-2006 3984 NOT FROM "Smith" 3985 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3986 //$ value is 2,10:15,21 3987 S: C283 OK SEARCH completed 3989 C: C284 SEARCH RETURN (SAVE MIN) SINCE 12-Feb-2006 3990 NOT FROM "Smith" 3991 S: * ESEARCH (TAG "C284") MIN 2 3992 //$ value is 2 3993 S: C284 OK SEARCH completed 3995 C: C285 SEARCH RETURN (MAX SAVE MIN) SINCE 3996 12-Feb-2006 NOT FROM "Smith" 3997 S: * ESEARCH (TAG "C285") MIN 2 MAX 21 3998 //$ value is 2,21 3999 S: C285 OK SEARCH completed 4001 C: C286 SEARCH RETURN (MAX SAVE MIN COUNT) 4002 SINCE 12-Feb-2006 NOT FROM "Smith" 4003 S: * ESEARCH (TAG "C286") MIN 2 MAX 21 COUNT 8 4004 //$ value is 2,10:15,21 4005 S: C286 OK SEARCH completed 4007 C: C286 SEARCH RETURN (ALL SAVE MIN) SINCE 4008 12-Feb-2006 NOT FROM "Smith" 4009 S: * ESEARCH (TAG "C286") MIN 2 ALL 2,10:15,21 4010 //$ value is 2,10:15,21 4011 S: C286 OK SEARCH completed 4013 6.4.5. FETCH Command 4015 Arguments: sequence set 4016 message data item names or macro 4018 Responses: untagged responses: FETCH 4020 Result: OK - fetch completed 4021 NO - fetch error: can't fetch that data 4022 BAD - command unknown or arguments invalid 4024 The FETCH command retrieves data associated with a message in the 4025 mailbox. The data items to be fetched can be either a single atom or 4026 a parenthesized list. 4028 Most data items, identified in the formal syntax under the msg-att- 4029 static rule, are static and MUST NOT change for any particular 4030 message. Other data items, identified in the formal syntax under the 4031 msg-att-dynamic rule, MAY change, either as a result of a STORE 4032 command or due to external events. 4034 For example, if a client receives an ENVELOPE for a message when 4035 it already knows the envelope, it can safely ignore the newly 4036 transmitted envelope. 4038 There are three macros which specify commonly-used sets of data 4039 items, and can be used instead of data items. A macro must be used 4040 by itself, and not in conjunction with other macros or data items. 4042 ALL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE) 4044 FAST Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE) 4046 FULL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE 4047 BODY) 4049 Several data items reference "section" or "section-binary". See 4050 Section 6.4.5.1 for their detailed definition. 4052 The currently defined data items that can be fetched are: 4054 BINARY[]<> 4056 Requests that the specified section be transmitted after 4057 performing Content-Transfer-Encoding-related decoding. 4059 The argument, if present, requests that a subset of 4060 the data be returned. The semantics of a partial FETCH BINARY 4061 command are the same as for a partial FETCH BODY command, with 4062 the exception that the arguments refer to the DECODED 4063 section data. 4065 Note that this data item can only be requested for leaf (i.e. 4066 non multipart/*, non message/rfc822 and non message/global) 4067 body parts. 4069 BINARY.PEEK[]<> An alternate form of 4070 BINARY[] that does not implicitly set the \Seen 4071 flag. 4073 BINARY.SIZE[] 4075 Requests the decoded size of the section (i.e., the size to 4076 expect in response to the corresponding FETCH BINARY request). 4078 Note: client authors are cautioned that this might be an 4079 expensive operation for some server implementations. 4080 Needlessly issuing this request could result in degraded 4081 performance due to servers having to calculate the value every 4082 time the request is issued. 4084 Note that this data item can only be requested for leaf (i.e. 4085 non multipart/*, non message/rfc822 and non message/global) 4086 body parts. 4088 BODY Non-extensible form of BODYSTRUCTURE. 4090 BODY[
]<> 4092 The text of a particular body section. 4094 It is possible to fetch a substring of the designated text. 4095 This is done by appending an open angle bracket ("<"), the 4096 octet position of the first desired octet, a period, the 4097 maximum number of octets desired, and a close angle bracket 4098 (">") to the part specifier. If the starting octet is beyond 4099 the end of the text, an empty string is returned. 4101 Any partial fetch that attempts to read beyond the end of the 4102 text is truncated as appropriate. A partial fetch that starts 4103 at octet 0 is returned as a partial fetch, even if this 4104 truncation happened. 4106 Note: This means that BODY[]<0.2048> of a 1500-octet message 4107 will return BODY[]<0> with a literal of size 1500, not 4108 BODY[]. 4110 Note: A substring fetch of a HEADER.FIELDS or 4111 HEADER.FIELDS.NOT part specifier is calculated after 4112 subsetting the header. 4114 The \Seen flag is implicitly set; if this causes the flags to 4115 change, they SHOULD be included as part of the FETCH responses. 4117 BODY.PEEK[
]<> An alternate form of BODY[
] 4118 that does not implicitly set the \Seen flag. 4120 BODYSTRUCTURE The [MIME-IMB] body structure of the message. This is 4121 computed by the server by parsing the [MIME-IMB] header fields in 4122 the [RFC-5322] header and [MIME-IMB] headers. See Section 7.4.2 4123 for more details. 4125 ENVELOPE The envelope structure of the message. This is computed by 4126 the server by parsing the [RFC-5322] header into the component 4127 parts, defaulting various fields as necessary. See Section 7.4.2 4128 for more details. 4130 FLAGS The flags that are set for this message. 4132 INTERNALDATE The internal date of the message. 4134 RFC822.SIZE The [RFC-5322] size of the message. 4136 UID The unique identifier for the message. 4138 Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)]) 4139 S: * 2 FETCH .... 4140 S: * 3 FETCH .... 4141 S: * 4 FETCH .... 4142 S: A654 OK FETCH completed 4144 6.4.5.1. FETCH section specification 4146 Several FETCH data items reference "section" or "section-binary". 4147 The section specification is a set of zero or more part specifiers 4148 delimited by periods. A part specifier is either a part number or 4149 one of the following: HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, 4150 and TEXT. (Non numeric part specifiers have to be the last specifier 4151 in a section specification.) An empty section specification refers 4152 to the entire message, including the header. 4154 Every message has at least one part number. Non-[MIME-IMB] messages, 4155 and non-multipart [MIME-IMB] messages with no encapsulated message, 4156 only have a part 1. 4158 Multipart messages are assigned consecutive part numbers, as they 4159 occur in the message. If a particular part is of type message or 4160 multipart, its parts MUST be indicated by a period followed by the 4161 part number within that nested multipart part. 4163 A part of type MESSAGE/RFC822 or MESSAGE/GLOBAL also has nested part 4164 numbers, referring to parts of the MESSAGE part's body. 4166 The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part 4167 specifiers can be the sole part specifier or can be prefixed by one 4168 or more numeric part specifiers, provided that the numeric part 4169 specifier refers to a part of type MESSAGE/RFC822 or MESSAGE/GLOBAL. 4170 The MIME part specifier MUST be prefixed by one or more numeric part 4171 specifiers. 4173 The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part specifiers 4174 refer to the [RFC-5322] header of the message or of an encapsulated 4175 [MIME-IMT] MESSAGE/RFC822 or MESSAGE/GLOBAL message. HEADER.FIELDS 4176 and HEADER.FIELDS.NOT are followed by a list of field-name (as 4177 defined in [RFC-5322]) names, and return a subset of the header. The 4178 subset returned by HEADER.FIELDS contains only those header fields 4179 with a field-name that matches one of the names in the list; 4180 similarly, the subset returned by HEADER.FIELDS.NOT contains only the 4181 header fields with a non-matching field-name. The field-matching is 4182 ASCII range case-insensitive but otherwise exact. Subsetting does 4183 not exclude the [RFC-5322] delimiting blank line between the header 4184 and the body; the blank line is included in all header fetches, 4185 except in the case of a message which has no body and no blank line. 4187 The MIME part specifier refers to the [MIME-IMB] header for this 4188 part. 4190 The TEXT part specifier refers to the text body of the message, 4191 omitting the [RFC-5322] header. 4193 Here is an example of a complex message with some of its part 4194 specifiers: 4196 HEADER ([RFC-5322] header of the message) 4197 TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4198 1 TEXT/PLAIN 4199 2 APPLICATION/OCTET-STREAM 4200 3 MESSAGE/RFC822 4201 3.HEADER ([RFC-5322] header of the message) 4202 3.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4203 3.1 TEXT/PLAIN 4204 3.2 APPLICATION/OCTET-STREAM 4205 4 MULTIPART/MIXED 4206 4.1 IMAGE/GIF 4207 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF) 4208 4.2 MESSAGE/RFC822 4209 4.2.HEADER ([RFC-5322] header of the message) 4210 4.2.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4211 4.2.1 TEXT/PLAIN 4212 4.2.2 MULTIPART/ALTERNATIVE 4213 4.2.2.1 TEXT/PLAIN 4214 4.2.2.2 TEXT/RICHTEXT 4216 6.4.6. STORE Command 4218 Arguments: sequence set 4219 message data item name 4220 value for message data item 4222 Responses: untagged responses: FETCH 4224 Result: OK - store completed 4225 NO - store error: can't store that data 4226 BAD - command unknown or arguments invalid 4228 The STORE command alters data associated with a message in the 4229 mailbox. Normally, STORE will return the updated value of the data 4230 with an untagged FETCH response. A suffix of ".SILENT" in the data 4231 item name prevents the untagged FETCH, and the server SHOULD assume 4232 that the client has determined the updated value itself or does not 4233 care about the updated value. 4235 Note: Regardless of whether or not the ".SILENT" suffix was used, 4236 the server SHOULD send an untagged FETCH response if a change to a 4237 message's flags from an external source is observed. The intent 4238 is that the status of the flags is determinate without a race 4239 condition. 4241 The currently defined data items that can be stored are: 4243 FLAGS Replace the flags for the message with the 4244 argument. The new value of the flags is returned as if a FETCH of 4245 those flags was done. 4247 FLAGS.SILENT Equivalent to FLAGS, but without returning 4248 a new value. 4250 +FLAGS Add the argument to the flags for the message. 4251 The new value of the flags is returned as if a FETCH of those 4252 flags was done. 4254 +FLAGS.SILENT Equivalent to +FLAGS, but without 4255 returning a new value. 4257 -FLAGS Remove the argument from the flags for the 4258 message. The new value of the flags is returned as if a FETCH of 4259 those flags was done. 4261 -FLAGS.SILENT Equivalent to -FLAGS, but without 4262 returning a new value. 4264 Example: C: A003 STORE 2:4 +FLAGS (\Deleted) 4265 S: * 2 FETCH (FLAGS (\Deleted \Seen)) 4266 S: * 3 FETCH (FLAGS (\Deleted)) 4267 S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen)) 4268 S: A003 OK STORE completed 4270 6.4.7. COPY Command 4272 Arguments: sequence set 4273 mailbox name 4275 Responses: no specific responses for this command 4277 Result: OK - copy completed 4278 NO - copy error: can't copy those messages or to that 4279 name 4280 BAD - command unknown or arguments invalid 4282 The COPY command copies the specified message(s) to the end of the 4283 specified destination mailbox. The flags and internal date of the 4284 message(s) SHOULD be preserved in the copy. 4286 If the destination mailbox does not exist, a server SHOULD return an 4287 error. It SHOULD NOT automatically create the mailbox. Unless it is 4288 certain that the destination mailbox can not be created, the server 4289 MUST send the response code "[TRYCREATE]" as the prefix of the text 4290 of the tagged NO response. This gives a hint to the client that it 4291 can attempt a CREATE command and retry the COPY if the CREATE is 4292 successful. 4294 If the COPY command is unsuccessful for any reason, server 4295 implementations MUST restore the destination mailbox to its state 4296 before the COPY attempt. 4298 On successful completion of a COPY, the server SHOULD return a 4299 COPYUID response code (see Section 7.1). 4301 In the case of a mailbox that has permissions set so that the client 4302 can COPY to the mailbox, but not SELECT or EXAMINE it, the server 4303 SHOULD NOT send an COPYUID response code as it would disclose 4304 information about the mailbox. 4306 In the case of a mailbox that has UIDNOTSTICKY status (see 4307 Section 7.1), the server MAY omit the COPYUID response code as it is 4308 not meaningful. 4310 If the server does not return the COPYUID response code, the client 4311 can discover this information by selecting the destination mailbox. 4313 The location of messages placed in the destination mailbox by COPY 4314 can be determined by using FETCH and/or SEARCH commands (e.g., for 4315 Message-ID). 4317 Example: C: A003 COPY 2:4 MEETING 4318 S: A003 OK COPY completed 4320 6.4.8. MOVE Command 4322 Arguments: sequence set 4323 mailbox name 4325 Responses: no specific responses for this command 4327 Result: OK - move completed 4328 NO - move error: can't move those messages or to that 4329 name 4330 BAD - command unknown or arguments invalid 4332 The MOVE command moves the specified message(s) to the end of the 4333 specified destination mailbox. The flags and internal date of the 4334 message(s) SHOULD be preserved. 4336 This means that a new message is created in the target mailbox with a 4337 new UID, the original message is removed from the source mailbox, and 4338 it appears to the client as a single action. This has the same 4339 effect for each message as this sequence: 4341 1. [UID] COPY 4343 2. [UID] STORE +FLAGS.SILENT \DELETED 4345 3. UID EXPUNGE 4347 Although the effect of the MOVE is the same as the preceding steps, 4348 the semantics are not identical: The intermediate states produced by 4349 those steps do not occur, and the response codes are different. In 4350 particular, though the COPY and EXPUNGE response codes will be 4351 returned, response codes for a STORE MUST NOT be generated and the 4352 \Deleted flag MUST NOT be set for any message. 4354 Because a MOVE applies to a set of messages, it might fail partway 4355 through the set. Regardless of whether the command is successful in 4356 moving the entire set, each individual message SHOULD either be moved 4357 or unaffected. The server MUST leave each message in a state where 4358 it is in at least one of the source or target mailboxes (no message 4359 can be lost or orphaned). The server SHOULD NOT leave any message in 4360 both mailboxes (it would be bad for a partial failure to result in a 4361 bunch of duplicate messages). This is true even if the server 4362 returns a tagged NO response to the command. 4364 Because of the similarity of MOVE to COPY, extensions that affect 4365 COPY affect MOVE in the same way. Response codes such as TRYCREATE 4366 (see Section 7.1), as well as those defined by extensions, are sent 4367 as appropriate. 4369 Servers SHOULD send COPYUID in response to a UID MOVE (see 4370 Section 6.4.9) command. For additional information see Section 7.1. 4372 Servers are also advised to send the COPYUID response code in an 4373 untagged OK before sending EXPUNGE or moved responses. (Sending 4374 COPYUID in the tagged OK, as described in the UIDPLUS specification, 4375 means that clients first receive an EXPUNGE for a message and 4376 afterwards COPYUID for the same message. It can be unnecessarily 4377 difficult to process that sequence usefully.) 4379 An example: 4380 C: a UID MOVE 42:69 foo 4381 S: * OK [COPYUID 432432 42:69 1202:1229] 4382 S: * 22 EXPUNGE 4383 S: (more expunges) 4384 S: a OK Done 4386 Note that the server may send unrelated EXPUNGE responses as well, if 4387 any happen to have been expunged at the same time; this is normal 4388 IMAP operation. 4390 Note that moving a message to the currently selected mailbox (that 4391 is, where the source and target mailboxes are the same) is allowed 4392 when copying the message to the currently selected mailbox is 4393 allowed. 4395 The server may send EXPUNGE responses before the tagged response, so 4396 the client cannot safely send more commands with message sequence 4397 number arguments while the server is processing MOVE. 4399 MOVE and UID MOVE can be pipelined with other commands, but care has 4400 to be taken. Both commands modify sequence numbers and also allow 4401 unrelated EXPUNGE responses. The renumbering of other messages in 4402 the source mailbox following any EXPUNGE response can be surprising 4403 and makes it unsafe to pipeline any command that relies on message 4404 sequence numbers after a MOVE or UID MOVE. Similarly, MOVE cannot be 4405 pipelined with a command that might cause message renumbering. See 4406 Section 5.5, for more information about ambiguities as well as 4407 handling requirements for both clients and servers. 4409 6.4.9. UID Command 4411 Arguments: command name 4412 command arguments 4414 Responses: untagged responses: FETCH, ESEARCH, EXPUNGE 4416 Result: OK - UID command completed 4417 NO - UID command error 4418 BAD - command unknown or arguments invalid 4420 The UID command has three forms. In the first form, it takes as its 4421 arguments a COPY, MOVE, FETCH, or STORE command with arguments 4422 appropriate for the associated command. However, the numbers in the 4423 sequence set argument are unique identifiers instead of message 4424 sequence numbers. Sequence set ranges are permitted, but there is no 4425 guarantee that unique identifiers will be contiguous. 4427 A non-existent unique identifier is ignored without any error message 4428 generated. Thus, it is possible for a UID FETCH command to return an 4429 OK without any data or a UID COPY, UID MOVE or UID STORE to return an 4430 OK without performing any operations. 4432 In the second form, the UID command takes an EXPUNGE command with an 4433 extra parameter the specified a sequence set of UIDs to operate on. 4434 The UID EXPUNGE command permanently removes all messages that both 4435 have the \Deleted flag set and have a UID that is included in the 4436 specified sequence set from the currently selected mailbox. If a 4437 message either does not have the \Deleted flag set or has a UID that 4438 is not included in the specified sequence set, it is not affected. 4440 UID EXPUNGE is particularly useful for disconnected use clients. 4441 By using UID EXPUNGE instead of EXPUNGE when resynchronizing with 4442 the server, the client can ensure that it does not inadvertantly 4443 remove any messages that have been marked as \Deleted by other 4444 clients between the time that the client was last connected and 4445 the time the client resynchronizes. 4447 Example: C: A003 UID EXPUNGE 3000:3002 4448 S: * 3 EXPUNGE 4449 S: * 3 EXPUNGE 4450 S: * 3 EXPUNGE 4451 S: A003 OK UID EXPUNGE completed 4453 In the third form, the UID command takes a SEARCH command with SEARCH 4454 command arguments. The interpretation of the arguments is the same 4455 as with SEARCH; however, the numbers returned in a ESEARCH response 4456 for a UID SEARCH command are unique identifiers instead of message 4457 sequence numbers. Also, the corresponding ESEARCH response MUST 4458 include the UID indicator. For example, the command UID SEARCH 1:100 4459 UID 443:557 returns the unique identifiers corresponding to the 4460 intersection of two sequence sets, the message sequence number range 4461 1:100 and the UID range 443:557. 4463 Note: in the above example, the UID range 443:557 appears. The 4464 same comment about a non-existent unique identifier being ignored 4465 without any error message also applies here. Hence, even if 4466 neither UID 443 or 557 exist, this range is valid and would 4467 include an existing UID 495. 4469 Also note that a UID range of 559:* always includes the UID of the 4470 last message in the mailbox, even if 559 is higher than any 4471 assigned UID value. This is because the contents of a range are 4472 independent of the order of the range endpoints. Thus, any UID 4473 range with * as one of the endpoints indicates at least one 4474 message (the message with the highest numbered UID), unless the 4475 mailbox is empty. 4477 The number after the "*" in an untagged FETCH or EXPUNGE response is 4478 always a message sequence number, not a unique identifier, even for a 4479 UID command response. However, server implementations MUST 4480 implicitly include the UID message data item as part of any FETCH 4481 response caused by a UID command, regardless of whether a UID was 4482 specified as a message data item to the FETCH. 4484 Note: The rule about including the UID message data item as part of a 4485 FETCH response primarily applies to the UID FETCH and UID STORE 4486 commands, including a UID FETCH command that does not include UID as 4487 a message data item. Although it is unlikely that the other UID 4488 commands will cause an untagged FETCH, this rule applies to these 4489 commands as well. 4491 Example: C: A999 UID FETCH 4827313:4828442 FLAGS 4492 S: * 23 FETCH (FLAGS (\Seen) UID 4827313) 4493 S: * 24 FETCH (FLAGS (\Seen) UID 4827943) 4494 S: * 25 FETCH (FLAGS (\Seen) UID 4828442) 4495 S: A999 OK UID FETCH completed 4497 6.5. Client Commands - Experimental/Expansion 4499 6.5.1. X Command 4501 Arguments: implementation defined 4503 Responses: implementation defined 4504 Result: OK - command completed 4505 NO - failure 4506 BAD - command unknown or arguments invalid 4508 Any command prefixed with an X is an experimental command. Commands 4509 which are not part of this specification, a standard or standards- 4510 track revision of this specification, or an IESG-approved 4511 experimental protocol, MUST use the X prefix. 4513 Any added untagged responses issued by an experimental command MUST 4514 also be prefixed with an X. Server implementations MUST NOT send any 4515 such untagged responses, unless the client requested it by issuing 4516 the associated experimental command. 4518 Example: C: a441 CAPABILITY 4519 S: * CAPABILITY IMAP4rev2 XPIG-LATIN 4520 S: a441 OK CAPABILITY completed 4521 C: A442 XPIG-LATIN 4522 S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay 4523 S: A442 OK XPIG-LATIN ompleted-cay 4525 7. Server Responses 4527 Server responses are in three forms: status responses, server data, 4528 and command continuation request. The information contained in a 4529 server response, identified by "Contents:" in the response 4530 descriptions below, is described by function, not by syntax. The 4531 precise syntax of server responses is described in the Formal Syntax 4532 section. 4534 The client MUST be prepared to accept any response at all times. 4536 Status responses can be tagged or untagged. Tagged status responses 4537 indicate the completion result (OK, NO, or BAD status) of a client 4538 command, and have a tag matching the command. 4540 Some status responses, and all server data, are untagged. An 4541 untagged response is indicated by the token "*" instead of a tag. 4542 Untagged status responses indicate server greeting, or server status 4543 that does not indicate the completion of a command (for example, an 4544 impending system shutdown alert). For historical reasons, untagged 4545 server data responses are also called "unsolicited data", although 4546 strictly speaking, only unilateral server data is truly 4547 "unsolicited". 4549 Certain server data MUST be recorded by the client when it is 4550 received; this is noted in the description of that data. Such data 4551 conveys critical information which affects the interpretation of all 4552 subsequent commands and responses (e.g., updates reflecting the 4553 creation or destruction of messages). 4555 Other server data SHOULD be recorded for later reference; if the 4556 client does not need to record the data, or if recording the data has 4557 no obvious purpose (e.g., a SEARCH response when no SEARCH command is 4558 in progress), the data SHOULD be ignored. 4560 An example of unilateral untagged server data occurs when the IMAP 4561 connection is in the selected state. In the selected state, the 4562 server checks the mailbox for new messages as part of command 4563 execution. Normally, this is part of the execution of every command; 4564 hence, a NOOP command suffices to check for new messages. If new 4565 messages are found, the server sends untagged EXISTS response 4566 reflecting the new size of the mailbox. Server implementations that 4567 offer multiple simultaneous access to the same mailbox SHOULD also 4568 send appropriate unilateral untagged FETCH and EXPUNGE responses if 4569 another agent changes the state of any message flags or expunges any 4570 messages. 4572 Command continuation request responses use the token "+" instead of a 4573 tag. These responses are sent by the server to indicate acceptance 4574 of an incomplete client command and readiness for the remainder of 4575 the command. 4577 7.1. Server Responses - Status Responses 4579 Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD 4580 can be tagged or untagged. PREAUTH and BYE are always untagged. 4582 Status responses MAY include an OPTIONAL "response code". A response 4583 code consists of data inside square brackets in the form of an atom, 4584 possibly followed by a space and arguments. The response code 4585 contains additional information or status codes for client software 4586 beyond the OK/NO/BAD condition, and are defined when there is a 4587 specific action that a client can take based upon the additional 4588 information. 4590 The currently defined response codes are: 4592 ALERT 4594 The human-readable text contains a special alert that MUST be 4595 presented to the user in a fashion that calls the user's 4596 attention to the message. 4598 ALREADYEXISTS 4599 The operation attempts to create something that already exists, 4600 such as when the CREATE or RENAME directories attempt to create 4601 a mailbox and there is already one of that name. 4603 C: o356 RENAME this that 4604 S: o356 NO [ALREADYEXISTS] Mailbox "that" already exists 4606 APPENDUID 4608 Followed by the UIDVALIDITY of the destination mailbox and the 4609 UID assigned to the appended message in the destination 4610 mailbox, indicates that the message has been appended to the 4611 destination mailbox with that UID. 4613 If the server also supports the [MULTIAPPEND] extension, and if 4614 multiple messages were appended in the APPEND command, then the 4615 second value is a UID set containing the UIDs assigned to the 4616 appended messages, in the order they were transmitted in the 4617 APPEND command. This UID set may not contain extraneous UIDs 4618 or the symbol "*". 4620 Note: the UID set form of the APPENDUID response code MUST 4621 NOT be used if only a single message was appended. In 4622 particular, a server MUST NOT send a range such as 123:123. 4623 This is because a client that does not support [MULTIAPPEND] 4624 expects only a single UID and not a UID set. 4626 UIDs are assigned in strictly ascending order in the mailbox 4627 (refer to Section 2.3.1.1); note that a range of 12:10 is 4628 exactly equivalent to 10:12 and refers to the sequence 4629 10,11,12. 4631 This response code is returned in a tagged OK response to the 4632 APPEND command. 4634 AUTHENTICATIONFAILED 4636 Authentication failed for some reason on which the server is 4637 unwilling to elaborate. Typically, this includes "unknown 4638 user" and "bad password". 4640 This is the same as not sending any response code, except that 4641 when a client sees AUTHENTICATIONFAILED, it knows that the 4642 problem wasn't, e.g., UNAVAILABLE, so there's no point in 4643 trying the same login/password again later. 4645 C: b LOGIN "fred" "foo" 4646 S: b NO [AUTHENTICATIONFAILED] Authentication failed 4648 AUTHORIZATIONFAILED 4650 Authentication succeeded in using the authentication identity, 4651 but the server cannot or will not allow the authentication 4652 identity to act as the requested authorization identity. This 4653 is only applicable when the authentication and authorization 4654 identities are different. 4656 C: c1 AUTHENTICATE PLAIN 4657 [...] 4658 S: c1 NO [AUTHORIZATIONFAILED] No such authorization-ID 4660 C: c2 AUTHENTICATE PLAIN 4661 [...] 4662 S: c2 NO [AUTHORIZATIONFAILED] Authenticator is not an admin 4664 BADCHARSET 4666 Optionally followed by a parenthesized list of charsets. A 4667 SEARCH failed because the given charset is not supported by 4668 this implementation. If the optional list of charsets is 4669 given, this lists the charsets that are supported by this 4670 implementation. 4672 CANNOT 4674 The operation violates some invariant of the server and can 4675 never succeed. 4677 C: l create "///////" 4678 S: l NO [CANNOT] Adjacent slashes are not supported 4680 CAPABILITY 4682 Followed by a list of capabilities. This can appear in the 4683 initial OK or PREAUTH response to transmit an initial 4684 capabilities list. It can also appear in tagged responses to 4685 LOGIN or AUTHENTICATE commands. This makes it unnecessary for 4686 a client to send a separate CAPABILITY command if it recognizes 4687 this response. 4689 CLIENTBUG 4690 The server has detected a client bug. This can accompany all 4691 of OK, NO, and BAD, depending on what the client bug is. 4693 C: k1 select "/archive/projects/experiment-iv" 4694 [...] 4695 S: k1 OK [READ-ONLY] Done 4696 C: k2 status "/archive/projects/experiment-iv" (messages) 4697 [...] 4698 S: k2 OK [CLIENTBUG] Done 4700 CLOSED 4702 The CLOSED response code has no parameters. A server return 4703 the CLOSED response code when the currently selected mailbox is 4704 closed implicitly using the SELECT/EXAMINE command on another 4705 mailbox. The CLOSED response code serves as a boundary between 4706 responses for the previously opened mailbox (which was closed) 4707 and the newly selected mailbox; all responses before the CLOSED 4708 response code relate to the mailbox that was closed, and all 4709 subsequent responses relate to the newly opened mailbox. 4711 There is no need to return the CLOSED response code on 4712 completion of the CLOSE or the UNSELECT command (or similar), 4713 whose purpose is to close the currently selected mailbox 4714 without opening a new one. 4716 CONTACTADMIN 4718 The user should contact the system administrator or support 4719 desk. 4721 C: e login "fred" "foo" 4722 S: e OK [CONTACTADMIN] 4724 COPYUID 4726 Followed by the UIDVALIDITY of the destination mailbox, a UID 4727 set containing the UIDs of the message(s) in the source mailbox 4728 that were copied to the destination mailbox and containing the 4729 UIDs assigned to the copied message(s) in the destination 4730 mailbox, indicates that the message(s) have been copied to the 4731 destination mailbox with the stated UID(s). 4733 The source UID set is in the order the message(s) were copied; 4734 the destination UID set corresponds to the source UID set and 4735 is in the same order. Neither of the UID sets may contain 4736 extraneous UIDs or the symbol "*". 4738 UIDs are assigned in strictly ascending order in the mailbox 4739 (refer to Section 2.3.1.1); note that a range of 12:10 is 4740 exactly equivalent to 10:12 and refers to the sequence 4741 10,11,12. 4743 This response code is returned in a tagged OK response to the 4744 COPY command. 4746 CORRUPTION 4748 The server discovered that some relevant data (e.g., the 4749 mailbox) are corrupt. This response code does not include any 4750 information about what's corrupt, but the server can write that 4751 to its logfiles. 4753 C: i select "/archive/projects/experiment-iv" 4754 S: i NO [CORRUPTION] Cannot open mailbox 4756 EXPIRED 4758 Either authentication succeeded or the server no longer had the 4759 necessary data; either way, access is no longer permitted using 4760 that passphrase. The client or user should get a new 4761 passphrase. 4763 C: d login "fred" "foo" 4764 S: d NO [EXPIRED] That password isn't valid any more 4766 EXPUNGEISSUED 4768 Someone else has issued an EXPUNGE for the same mailbox. The 4769 client may want to issue NOOP soon. [IMAP-MULTIACCESS] 4770 discusses this subject in depth. 4772 C: h search from fred@example.com 4773 S: * ESEARCH (TAG "h") ALL 1:3,5,8,13,21,42 4774 S: h OK [EXPUNGEISSUED] Search completed 4776 HASCHILDREN 4778 The mailbox delete operation failed because the mailbox has one 4779 or more children and the server doesn't allow deletion of 4780 mailboxes with children. 4782 C: m356 DELETE Notes 4783 S: o356 NO [HASCHILDREN] Mailbox "Notes" has children that need 4784 to be deleted first 4786 INUSE 4788 An operation has not been carried out because it involves 4789 sawing off a branch someone else is sitting on. Someone else 4790 may be holding an exclusive lock needed for this operation, or 4791 the operation may involve deleting a resource someone else is 4792 using, typically a mailbox. 4794 The operation may succeed if the client tries again later. 4796 C: g delete "/archive/projects/experiment-iv" 4797 S: g NO [INUSE] Mailbox in use 4799 LIMIT 4801 The operation ran up against an implementation limit of some 4802 kind, such as the number of flags on a single message or the 4803 number of flags used in a mailbox. 4805 C: m STORE 42 FLAGS f1 f2 f3 f4 f5 ... f250 4806 S: m NO [LIMIT] At most 32 flags in one mailbox supported 4808 NONEXISTENT 4810 The operation attempts to delete something that does not exist. 4811 Similar to ALREADYEXISTS. 4813 C: p RENAME this that 4814 S: p NO [NONEXISTENT] No such mailbox 4816 NOPERM 4818 The access control system (e.g., Access Control List (ACL), see 4819 [RFC4314] does not permit this user to carry out an operation, 4820 such as selecting or creating a mailbox. 4822 C: f select "/archive/projects/experiment-iv" 4823 S: f NO [NOPERM] Access denied 4825 OVERQUOTA 4827 The user would be over quota after the operation. (The user 4828 may or may not be over quota already.) 4830 Note that if the server sends OVERQUOTA but doesn't support the 4831 IMAP QUOTA extension defined by [RFC2087], then there is a 4832 quota, but the client cannot find out what the quota is. 4834 C: n1 uid copy 1:* oldmail 4835 S: n1 NO [OVERQUOTA] Sorry 4837 C: n2 uid copy 1:* oldmail 4838 S: n2 OK [OVERQUOTA] You are now over your soft quota 4840 PARSE 4842 The human-readable text represents an error in parsing the 4843 [RFC-5322] header or [MIME-IMB] headers of a message in the 4844 mailbox. 4846 PERMANENTFLAGS 4848 Followed by a parenthesized list of flags, indicates which of 4849 the known flags the client can change permanently. Any flags 4850 that are in the FLAGS untagged response, but not the 4851 PERMANENTFLAGS list, can not be set permanently. The 4852 PERMANENTFLAGS list can also include the special flag \*, which 4853 indicates that it is possible to create new keywords by 4854 attempting to store those keywords in the mailbox. If the 4855 client attempts to STORE a flag that is not in the 4856 PERMANENTFLAGS list, the server will either ignore the change 4857 or store the state change for the remainder of the current 4858 session only. 4860 There is no need for a server that included the special flag \* 4861 to return a new PERMANENTFLAGS response code when a new keyword 4862 was successfully set on a message upon client request. However 4863 if the server has a limit on the number of different keywords 4864 that can be stored in a mailbox and that limit is reached, the 4865 server MUST send a new PERMANENTFLAGS response code without the 4866 special flag \*. 4868 PRIVACYREQUIRED 4870 The operation is not permitted due to a lack of privacy. If 4871 Transport Layer Security (TLS) is not in use, the client could 4872 try STARTTLS (see Section 6.2.1) and then repeat the operation. 4874 C: d login "fred" "foo" 4875 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4877 C: d select inbox 4878 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4880 READ-ONLY 4882 The mailbox is selected read-only, or its access while selected 4883 has changed from read-write to read-only. 4885 READ-WRITE 4887 The mailbox is selected read-write, or its access while 4888 selected has changed from read-only to read-write. 4890 SERVERBUG 4892 The server encountered a bug in itself or violated one of its 4893 own invariants. 4895 C: j select "/archive/projects/experiment-iv" 4896 S: j NO [SERVERBUG] This should not happen 4898 TRYCREATE 4900 An APPEND or COPY attempt is failing because the target mailbox 4901 does not exist (as opposed to some other reason). This is a 4902 hint to the client that the operation can succeed if the 4903 mailbox is first created by the CREATE command. 4905 UIDNEXT 4907 Followed by a decimal number, indicates the next unique 4908 identifier value. Refer to Section 2.3.1.1 for more 4909 information. 4911 UIDNOTSTICKY 4913 The selected mailbox is supported by a mail store that does not 4914 support persistent UIDs; that is, UIDVALIDITY will be different 4915 each time the mailbox is selected. Consequently, APPEND or 4916 COPY to this mailbox will not return an APPENDUID or COPYUID 4917 response code. 4919 This response code is returned in an untagged NO response to 4920 the SELECT command. 4922 Note: servers SHOULD NOT have any UIDNOTSTICKY mail stores. 4923 This facility exists to support legacy mail stores in which 4924 it is technically infeasible to support persistent UIDs. 4925 This should be avoided when designing new mail stores. 4927 UIDVALIDITY 4929 Followed by a decimal number, indicates the unique identifier 4930 validity value. Refer to Section 2.3.1.1 for more information. 4932 UNAVAILABLE 4934 Temporary failure because a subsystem is down. For example, an 4935 IMAP server that uses a Lightweight Directory Access Protocol 4936 (LDAP) or Radius server for authentication might use this 4937 response code when the LDAP/Radius server is down. 4939 C: a LOGIN "fred" "foo" 4940 S: a NO [UNAVAILABLE] User's backend down for maintenance 4942 UNKNOWN-CTE 4944 The server does not know how to decode the section's Content- 4945 Transfer-Encoding. 4947 Client implementations MUST ignore response codes that they do not 4948 recognize. 4950 7.1.1. OK Response 4952 Contents: OPTIONAL response code 4953 human-readable text 4955 The OK response indicates an information message from the server. 4956 When tagged, it indicates successful completion of the associated 4957 command. The human-readable text MAY be presented to the user as an 4958 information message. The untagged form indicates an information-only 4959 message; the nature of the information MAY be indicated by a response 4960 code. 4962 The untagged form is also used as one of three possible greetings at 4963 connection startup. It indicates that the connection is not yet 4964 authenticated and that a LOGIN or an AUTHENTICATE command is needed. 4966 Example: S: * OK IMAP4rev2 server ready 4967 C: A001 LOGIN fred blurdybloop 4968 S: * OK [ALERT] System shutdown in 10 minutes 4969 S: A001 OK LOGIN Completed 4971 7.1.2. NO Response 4973 Contents: OPTIONAL response code 4974 human-readable text 4976 The NO response indicates an operational error message from the 4977 server. When tagged, it indicates unsuccessful completion of the 4978 associated command. The untagged form indicates a warning; the 4979 command can still complete successfully. The human-readable text 4980 describes the condition. 4982 Example: C: A222 COPY 1:2 owatagusiam 4983 S: * NO Disk is 98% full, please delete unnecessary data 4984 S: A222 OK COPY completed 4985 C: A223 COPY 3:200 blurdybloop 4986 S: * NO Disk is 98% full, please delete unnecessary data 4987 S: * NO Disk is 99% full, please delete unnecessary data 4988 S: A223 NO COPY failed: disk is full 4990 7.1.3. BAD Response 4992 Contents: OPTIONAL response code 4993 human-readable text 4995 The BAD response indicates an error message from the server. When 4996 tagged, it reports a protocol-level error in the client's command; 4997 the tag indicates the command that caused the error. The untagged 4998 form indicates a protocol-level error for which the associated 4999 command can not be determined; it can also indicate an internal 5000 server failure. The human-readable text describes the condition. 5002 Example: C: ...very long command line... 5003 S: * BAD Command line too long 5004 C: ...empty line... 5005 S: * BAD Empty command line 5006 C: A443 EXPUNGE 5007 S: * BAD Disk crash, attempting salvage to a new disk! 5008 S: * OK Salvage successful, no data lost 5009 S: A443 OK Expunge completed 5011 7.1.4. PREAUTH Response 5013 Contents: OPTIONAL response code 5014 human-readable text 5016 The PREAUTH response is always untagged, and is one of three possible 5017 greetings at connection startup. It indicates that the connection 5018 has already been authenticated by external means; thus no LOGIN/ 5019 AUTHENTICATE command is needed. 5021 Example: S: * PREAUTH IMAP4rev2 server logged in as Smith 5023 7.1.5. BYE Response 5025 Contents: OPTIONAL response code 5026 human-readable text 5028 The BYE response is always untagged, and indicates that the server is 5029 about to close the connection. The human-readable text MAY be 5030 displayed to the user in a status report by the client. The BYE 5031 response is sent under one of four conditions: 5033 1. as part of a normal logout sequence. The server will close the 5034 connection after sending the tagged OK response to the LOGOUT 5035 command. 5037 2. as a panic shutdown announcement. The server closes the 5038 connection immediately. 5040 3. as an announcement of an inactivity autologout. The server 5041 closes the connection immediately. 5043 4. as one of three possible greetings at connection startup, 5044 indicating that the server is not willing to accept a connection 5045 from this client. The server closes the connection immediately. 5047 The difference between a BYE that occurs as part of a normal LOGOUT 5048 sequence (the first case) and a BYE that occurs because of a failure 5049 (the other three cases) is that the connection closes immediately in 5050 the failure case. In all cases the client SHOULD continue to read 5051 response data from the server until the connection is closed; this 5052 will ensure that any pending untagged or completion responses are 5053 read and processed. 5055 Example: S: * BYE Autologout; idle for too long 5057 7.2. Server Responses - Server and Mailbox Status 5059 These responses are always untagged. This is how server and mailbox 5060 status data are transmitted from the server to the client. Many of 5061 these responses typically result from a command with the same name. 5063 7.2.1. The ENABLED Response 5065 Contents: capability listing 5067 The ENABLED response occurs as a result of an ENABLE command. The 5068 capability listing contains a space-separated listing of capability 5069 names that the server supports and that were successfully enabled. 5070 The ENABLED response may contain no capabilities, which means that no 5071 extensions listed by the client were successfully enabled. 5073 7.2.2. CAPABILITY Response 5075 Contents: capability listing 5077 The CAPABILITY response occurs as a result of a CAPABILITY command. 5078 The capability listing contains a space-separated listing of 5079 capability names that the server supports. The capability listing 5080 MUST include the atom "IMAP4rev2". 5082 In addition, client and server implementations MUST implement the 5083 STARTTLS, LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) 5084 capabilities. See the Security Considerations section for important 5085 information. 5087 A capability name which begins with "AUTH=" indicates that the server 5088 supports that particular authentication mechanism. 5090 The LOGINDISABLED capability indicates that the LOGIN command is 5091 disabled, and that the server will respond with a tagged NO response 5092 to any attempt to use the LOGIN command even if the user name and 5093 password are valid. An IMAP client MUST NOT issue the LOGIN command 5094 if the server advertises the LOGINDISABLED capability. 5096 Other capability names indicate that the server supports an 5097 extension, revision, or amendment to the IMAP4rev2 protocol. Server 5098 responses MUST conform to this document until the client issues a 5099 command that uses the associated capability. 5101 Capability names MUST either begin with "X" or be informational, 5102 experimental or standards-track IMAP4rev2 extensions, revisions, or 5103 amendments registered with IANA. A server SHOULD NOT offer 5104 unregistered or non-standard capability names, unless such names are 5105 prefixed with an "X". 5107 Client implementations SHOULD NOT require any capability name other 5108 than "IMAP4rev2", and MUST ignore any unknown capability names. 5110 A server MAY send capabilities automatically, by using the CAPABILITY 5111 response code in the initial PREAUTH or OK responses, and by sending 5112 an updated CAPABILITY response code in the tagged OK response as part 5113 of a successful authentication. It is unnecessary for a client to 5114 send a separate CAPABILITY command if it recognizes these automatic 5115 capabilities. 5117 Example: S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI XPIG-LATIN 5119 7.2.3. LIST Response 5121 Contents: name attributes 5122 hierarchy delimiter 5123 name 5124 OPTIONAL extension data 5126 The LIST response occurs as a result of a LIST command. It returns a 5127 single name that matches the LIST specification. There can be 5128 multiple LIST responses for a single LIST command. 5130 The following base mailbox name attributes are defined: 5132 \NonExistent The "\NonExistent" attribute indicates that a mailbox 5133 name does not refer to an existing mailbox. Note that this 5134 attribute is not meaningful by itself, as mailbox names that match 5135 the canonical LIST pattern but don't exist must not be returned 5136 unless one of the two conditions listed below is also satisfied: 5138 1. The mailbox name also satisfies the selection criteria (for 5139 example, it is subscribed and the "SUBSCRIBED" selection 5140 option has been specified). 5142 2. "RECURSIVEMATCH" has been specified, and the mailbox name has 5143 at least one descendant mailbox name that does not match the 5144 LIST pattern and does match the selection criteria. 5146 In practice, this means that the "\NonExistent" attribute is 5147 usually returned with one or more of "\Subscribed", "\Remote", 5148 "\HasChildren", or the CHILDINFO extended data item. 5150 The "\NonExistent" attribute implies "\NoSelect". 5152 \Noinferiors It is not possible for any child levels of hierarchy to 5153 exist under this name; no child levels exist now and none can be 5154 created in the future. 5156 \Noselect It is not possible to use this name as a selectable 5157 mailbox. 5159 \HasChildren The presence of this attribute indicates that the 5160 mailbox has child mailboxes. A server SHOULD NOT set this 5161 attribute if there are child mailboxes and the user does not have 5162 permission to access any of them. In this case, \HasNoChildren 5163 SHOULD be used. In many cases, however, a server may not be able 5164 to efficiently compute whether a user has access to any child 5165 mailbox. Note that even though the \HasChildren attribute for a 5166 mailbox must be correct at the time of processing of the mailbox, 5167 a client must be prepared to deal with a situation when a mailbox 5168 is marked with the \HasChildren attribute, but no child mailbox 5169 appears in the response to the LIST command. This might happen, 5170 for example, due to children mailboxes being deleted or made 5171 inaccessible to the user (using access control) by another client 5172 before the server is able to list them. 5174 \HasNoChildren The presence of this attribute indicates that the 5175 mailbox has NO child mailboxes that are accessible to the 5176 currently authenticated user. 5178 \Marked The mailbox has been marked "interesting" by the server; the 5179 mailbox probably contains messages that have been added since the 5180 last time the mailbox was selected. 5182 \Unmarked The mailbox does not contain any additional messages since 5183 the last time the mailbox was selected. 5185 \Subscribed The mailbox name was subscribed to using the SUBSCRIBE 5186 command. 5188 \Remote The mailbox is a remote mailbox. 5190 It is an error for the server to return both a \HasChildren and a 5191 \HasNoChildren attribute in the same LIST response. A client that 5192 encounters a LIST response with both \HasChildren and \HasNoChildren 5193 attributes present should act as if both are absent in the LIST 5194 response. 5196 Note: the \HasNoChildren attribute should not be confused with the 5197 \NoInferiors attribute, which indicates that no child mailboxes 5198 exist now and none can be created in the future. 5200 If it is not feasible for the server to determine whether or not the 5201 mailbox is "interesting", the server SHOULD NOT send either \Marked 5202 or \Unmarked. The server MUST NOT send more than one of \Marked, 5203 \Unmarked, and \Noselect for a single mailbox, and MAY send none of 5204 these. 5206 In addition to the base mailbox name attributes defined above, an 5207 IMAP server MAY also include any or all of the following attributes 5208 that denote "role" (or "special-use") of a mailbox. These attributes 5209 are included along with base attributes defined above. A given 5210 mailbox may have none, one, or more than one of these attributes. In 5211 some cases, a special use is advice to a client about what to put in 5212 that mailbox. In other cases, it's advice to a client about what to 5213 expect to find there. 5215 \All This mailbox presents all messages in the user's message store. 5216 Implementations MAY omit some messages, such as, perhaps, those in 5217 \Trash and \Junk. When this special use is supported, it is 5218 almost certain to represent a virtual mailbox. 5220 \Archive This mailbox is used to archive messages. The meaning of 5221 an "archival" mailbox is server-dependent; typically, it will be 5222 used to get messages out of the inbox, or otherwise keep them out 5223 of the user's way, while still making them accessible. 5225 \Drafts This mailbox is used to hold draft messages -- typically, 5226 messages that are being composed but have not yet been sent. In 5227 some server implementations, this might be a virtual mailbox, 5228 containing messages from other mailboxes that are marked with the 5229 "\Draft" message flag. Alternatively, this might just be advice 5230 that a client put drafts here. 5232 \Flagged This mailbox presents all messages marked in some way as 5233 "important". When this special use is supported, it is likely to 5234 represent a virtual mailbox collecting messages (from other 5235 mailboxes) that are marked with the "\Flagged" message flag. 5237 \Junk This mailbox is where messages deemed to be junk mail are 5238 held. Some server implementations might put messages here 5239 automatically. Alternatively, this might just be advice to a 5240 client-side spam filter. 5242 \Sent This mailbox is used to hold copies of messages that have been 5243 sent. Some server implementations might put messages here 5244 automatically. Alternatively, this might just be advice that a 5245 client save sent messages here. 5247 \Trash This mailbox is used to hold messages that have been deleted 5248 or marked for deletion. In some server implementations, this 5249 might be a virtual mailbox, containing messages from other 5250 mailboxes that are marked with the "\Deleted" message flag. 5251 Alternatively, this might just be advice that a client that 5252 chooses not to use the IMAP "\Deleted" model should use this as 5253 its trash location. In server implementations that strictly 5254 expect the IMAP "\Deleted" model, this special use is likely not 5255 to be supported. 5257 All of special-use attributes are OPTIONAL, and any given server or 5258 message store may support any combination of the attributes, or none 5259 at all. In most cases, there will likely be at most one mailbox with 5260 a given attribute for a given user, but in some server or message 5261 store implementations it might be possible for multiple mailboxes to 5262 have the same special-use attribute. 5264 Special-use attributes are likely to be user-specific. User Adam 5265 might share his \Sent mailbox with user Barb, but that mailbox is 5266 unlikely to also serve as Barb's \Sent mailbox. 5268 Other mailbox name attributes can be found in the "IMAP Mailbox Name 5269 Attributes" registry [IMAP-MAILBOX-NAME-ATTRS-REG]. 5271 The hierarchy delimiter is a character used to delimit levels of 5272 hierarchy in a mailbox name. A client can use it to create child 5273 mailboxes, and to search higher or lower levels of naming hierarchy. 5274 All children of a top-level hierarchy node MUST use the same 5275 separator character. A NIL hierarchy delimiter means that no 5276 hierarchy exists; the name is a "flat" name. 5278 The name represents an unambiguous left-to-right hierarchy, and MUST 5279 be valid for use as a reference in LIST command. Unless \Noselect or 5280 \NonExistent is indicated, the name MUST also be valid as an argument 5281 for commands, such as SELECT, that accept mailbox names. 5283 The name might be followed by an OPTIONAL series of extended fields, 5284 a parenthesized list of tagged data (also referred to as "extended 5285 data item"). The first element of an extended field is a string, 5286 which identifies the type of data. [RFC5258] specified requirements 5287 on string registration (which are called "tags" there; such tags are 5288 not to be confused with IMAP command tags), in particular it said 5289 that "Tags MUST be registered with IANA". This document doesn't 5290 change that. See Section 9.5 of [RFC5258] for the registration 5291 template. The server MAY return data in the extended fields that was 5292 not directly solicited by the client in the corresponding LIST 5293 command. For example, the client can enable extra extended fields by 5294 using another IMAP extension that make use of the extended LIST 5295 responses. The client MUST ignore all extended fields it doesn't 5296 recognize. 5298 Example: S: * LIST (\Noselect) "/" ~/Mail/foo 5300 Example: S: * LIST (\Marked) ":" Tables (tablecloth (("edge" "lacy") 5301 ("color" "red")) Sample "text") 5302 S: * LIST () ":" Tables:new (tablecloth ("edge" "lacy") 5303 Sample ("text" "more text")) 5305 7.2.4. NAMESPACE Response 5307 Contents: the prefix and hierarchy delimiter to the server's 5308 Personal Namespace(s), Other Users' Namespace(s), and 5309 Shared Namespace(s) 5311 The NAMESPACE response occurs as a result of a NAMESPACE command. It 5312 contains the prefix and hierarchy delimiter to the server's Personal 5313 Namespace(s), Other Users' Namespace(s), and Shared Namespace(s) that 5314 the server wishes to expose. The response will contain a NIL for any 5315 namespace class that is not available. Namespace-Response-Extensions 5316 ABNF non terminal is defined for extensibility and MAY be included in 5317 the response. 5319 Example: S: * NAMESPACE (("" "/")) (("~" "/")) NIL 5321 7.2.5. STATUS Response 5323 Contents: name 5324 status parenthesized list 5326 The STATUS response occurs as a result of an STATUS command. It 5327 returns the mailbox name that matches the STATUS specification and 5328 the requested mailbox status information. 5330 Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 5332 7.2.6. ESEARCH Response 5334 Contents: one or more search-return-data pairs 5336 The ESEARCH response occurs as a result of a SEARCH or UID SEARCH 5337 command. 5339 The ESEARCH response starts with an optional search correlator. If 5340 it is missing, then the response was not caused by a particular IMAP 5341 command, whereas if it is present, it contains the tag of the command 5342 that caused the response to be returned. 5344 The search correlator is followed by an optional UID indicator. If 5345 this indicator is present, all data in the ESEARCH response refers to 5346 UIDs, otherwise all returned data refers to message numbers. 5348 The rest of the ESEARCH response contains one or more search data 5349 pairs. Each pair starts with unique return item name, followed by a 5350 space and the corresponding data. Search data pairs may be returned 5351 in any order. Unless specified otherwise by an extension, any return 5352 item name SHOULD appear only once in an ESEARCH response. 5354 [[TBD: describe the most common search data pairs returned.]] 5356 Example: S: * ESEARCH UID COUNT 5 ALL 4:19,21,28 5358 Example: S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28 5360 Example: S: * ESEARCH COUNT 5 ALL 1:17,21 5362 7.2.7. FLAGS Response 5364 Contents: flag parenthesized list 5366 The FLAGS response occurs as a result of a SELECT or EXAMINE command. 5367 The flag parenthesized list identifies the flags (at a minimum, the 5368 system-defined flags) that are applicable for this mailbox. Flags 5369 other than the system flags can also exist, depending on server 5370 implementation. 5372 The update from the FLAGS response MUST be recorded by the client. 5374 Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5376 7.3. Server Responses - Mailbox Size 5378 These responses are always untagged. This is how changes in the size 5379 of the mailbox are transmitted from the server to the client. 5380 Immediately following the "*" token is a number that represents a 5381 message count. 5383 7.3.1. EXISTS Response 5385 Contents: none 5387 The EXISTS response reports the number of messages in the mailbox. 5388 This response occurs as a result of a SELECT or EXAMINE command, and 5389 if the size of the mailbox changes (e.g., new messages). 5391 The update from the EXISTS response MUST be recorded by the client. 5393 Example: S: * 23 EXISTS 5395 7.4. Server Responses - Message Status 5397 These responses are always untagged. This is how message data are 5398 transmitted from the server to the client, often as a result of a 5399 command with the same name. Immediately following the "*" token is a 5400 number that represents a message sequence number. 5402 7.4.1. EXPUNGE Response 5404 Contents: none 5406 The EXPUNGE response reports that the specified message sequence 5407 number has been permanently removed from the mailbox. The message 5408 sequence number for each successive message in the mailbox is 5409 immediately decremented by 1, and this decrement is reflected in 5410 message sequence numbers in subsequent responses (including other 5411 untagged EXPUNGE responses). 5413 The EXPUNGE response also decrements the number of messages in the 5414 mailbox; it is not necessary to send an EXISTS response with the new 5415 value. 5417 As a result of the immediate decrement rule, message sequence numbers 5418 that appear in a set of successive EXPUNGE responses depend upon 5419 whether the messages are removed starting from lower numbers to 5420 higher numbers, or from higher numbers to lower numbers. For 5421 example, if the last 5 messages in a 9-message mailbox are expunged, 5422 a "lower to higher" server will send five untagged EXPUNGE responses 5423 for message sequence number 5, whereas a "higher to lower server" 5424 will send successive untagged EXPUNGE responses for message sequence 5425 numbers 9, 8, 7, 6, and 5. 5427 An EXPUNGE response MUST NOT be sent when no command is in progress, 5428 nor while responding to a FETCH, STORE, or SEARCH command. This rule 5429 is necessary to prevent a loss of synchronization of message sequence 5430 numbers between client and server. A command is not "in progress" 5431 until the complete command has been received; in particular, a 5432 command is not "in progress" during the negotiation of command 5433 continuation. 5435 Note: UID FETCH, UID STORE, and UID SEARCH are different commands 5436 from FETCH, STORE, and SEARCH. An EXPUNGE response MAY be sent 5437 during a UID command. 5439 The update from the EXPUNGE response MUST be recorded by the client. 5441 Example: S: * 44 EXPUNGE 5443 7.4.2. FETCH Response 5445 Contents: message data 5447 The FETCH response returns data about a message to the client. The 5448 data are pairs of data item names and their values in parentheses. 5449 This response occurs as the result of a FETCH or STORE command, as 5450 well as by unilateral server decision (e.g., flag updates). 5452 The current data items are: 5454 BINARY[]<> 5456 An or expressing the content of the 5457 specified section after removing any Content-Transfer-Encoding- 5458 related encoding. If is present it refers to the 5459 offset within the DECODED section data. 5461 If the domain of the decoded data is "8bit" and the data does 5462 not contain the NUL octet, the server SHOULD return the data in 5463 a instead of a ; this allows the client to 5464 determine if the "8bit" data contains the NUL octet without 5465 having to explicitly scan the data stream for for NULs. 5467 Messaging clients and servers have been notoriously lax in 5468 their adherence to the Internet CRLF convention for terminating 5469 lines of textual data (text/* media types) in Internet 5470 protocols. When sending data in BINARY[...] FETCH data item, 5471 servers MUST ensure that textual line-oriented sections are 5472 always transmitted using the IMAP4 CRLF line termination 5473 syntax, regardless of the underlying storage representation of 5474 the data on the server. 5476 If the server does not know how to decode the section's 5477 Content-Transfer-Encoding, it MUST fail the request and issue a 5478 "NO" response that contains the "UNKNOWN-CTE" response code. 5480 BINARY.SIZE[] 5482 The size of the section after removing any Content-Transfer- 5483 Encoding-related encoding. The value returned MUST match the 5484 size of the or that will be returned by 5485 the corresponding FETCH BINARY request. 5487 If the server does not know how to decode the section's 5488 Content-Transfer-Encoding, it MUST fail the request and issue a 5489 "NO" response that contains the "UNKNOWN-CTE" response code. 5491 BODY A form of BODYSTRUCTURE without extension data. 5493 BODY[
]<> 5495 A string expressing the body contents of the specified section. 5496 The string SHOULD be interpreted by the client according to the 5497 content transfer encoding, body type, and subtype. 5499 If the origin octet is specified, this string is a substring of 5500 the entire body contents, starting at that origin octet. This 5501 means that BODY[]<0> MAY be truncated, but BODY[] is NEVER 5502 truncated. 5504 Note: The origin octet facility MUST NOT be used by a server 5505 in a FETCH response unless the client specifically requested 5506 it by means of a FETCH of a BODY[
]<> data 5507 item. 5509 8-bit textual data is permitted if a [CHARSET] identifier is 5510 part of the body parameter parenthesized list for this section. 5511 Note that headers (part specifiers HEADER or MIME, or the 5512 header portion of a MESSAGE/RFC822 or MESSAGE/GLOBAL part), MAY 5513 be in UTF-8. Note also that the [RFC-5322] delimiting blank 5514 line between the header and the body is not affected by header 5515 line subsetting; the blank line is always included as part of 5516 header data, except in the case of a message which has no body 5517 and no blank line. 5519 Non-textual data such as binary data MUST be transfer encoded 5520 into a textual form, such as BASE64, prior to being sent to the 5521 client. To derive the original binary data, the client MUST 5522 decode the transfer encoded string. 5524 BODYSTRUCTURE 5526 A parenthesized list that describes the [MIME-IMB] body 5527 structure of a message. This is computed by the server by 5528 parsing the [MIME-IMB] header fields, defaulting various fields 5529 as necessary. 5531 For example, a simple text message of 48 lines and 2279 octets 5532 can have a body structure of: ("TEXT" "PLAIN" ("CHARSET" "US- 5533 ASCII") NIL NIL "7BIT" 2279 48) 5535 Multiple parts are indicated by parenthesis nesting. Instead 5536 of a body type as the first element of the parenthesized list, 5537 there is a sequence of one or more nested body structures. The 5538 second element of the parenthesized list is the multipart 5539 subtype (mixed, digest, parallel, alternative, etc.). 5541 For example, a two part message consisting of a text and a 5542 BASE64-encoded text attachment can have a body structure of: 5543 (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 5544 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") 5545 "<960723163407.20117h@cac.washington.edu>" "Compiler diff" 5546 "BASE64" 4554 73) "MIXED") 5548 Extension data follows the multipart subtype. Extension data 5549 is never returned with the BODY fetch, but can be returned with 5550 a BODYSTRUCTURE fetch. Extension data, if present, MUST be in 5551 the defined order. The extension data of a multipart body part 5552 are in the following order: 5554 body parameter parenthesized list A parenthesized list of 5555 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5556 "bar" is the value of "foo", and "rag" is the value of 5557 "baz"] as defined in [MIME-IMB]. Servers SHOULD decode 5558 parameter value continuations and parameter value character 5559 sets as described in [RFC2231], for example, if the message 5560 contains parameters "baz*0", "baz*1" and "baz*2", the server 5561 should RFC2231-decode them, concatenate and return the 5562 resulting value as a parameter "baz". Similarly, if the 5563 message contains parameters "foo*0*" and "foo*1*", the 5564 server should RFC2231-decode them, convert to UTF-8, 5565 concatenate and return the resulting value as a parameter 5566 "foo*". 5568 body disposition A parenthesized list, consisting of a 5569 disposition type string, followed by a parenthesized list of 5570 disposition attribute/value pairs as defined in 5571 [DISPOSITION]. Servers SHOULD decode parameter value 5572 continuations as described in [RFC2231]. 5574 body language A string or parenthesized list giving the body 5575 language value as defined in [LANGUAGE-TAGS]. 5577 body location A string giving the body content URI as defined 5578 in [LOCATION]. 5580 Any following extension data are not yet defined in this 5581 version of the protocol. Such extension data can consist of 5582 zero or more NILs, strings, numbers, or potentially nested 5583 parenthesized lists of such data. Client implementations that 5584 do a BODYSTRUCTURE fetch MUST be prepared to accept such 5585 extension data. Server implementations MUST NOT send such 5586 extension data until it has been defined by a revision of this 5587 protocol. 5589 The basic fields of a non-multipart body part are in the 5590 following order: 5592 body type A string giving the content media type name as 5593 defined in [MIME-IMB]. 5595 body subtype A string giving the content subtype name as 5596 defined in [MIME-IMB]. 5598 body parameter parenthesized list A parenthesized list of 5599 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5600 "bar" is the value of "foo" and "rag" is the value of "baz"] 5601 as defined in [MIME-IMB]. 5603 body id A string giving the Content-ID header field value as 5604 defined in Section 7 of [MIME-IMB]. 5606 body description A string giving the Content-Description 5607 header field value as defined in Section 8 of [MIME-IMB]. 5609 body encoding A string giving the content transfer encoding as 5610 defined in Section 6 of [MIME-IMB]. 5612 body size A number giving the size of the body in octets. 5613 Note that this size is the size in its transfer encoding and 5614 not the resulting size after any decoding. 5616 A body type of type MESSAGE and subtype RFC822 contains, 5617 immediately after the basic fields, the envelope structure, 5618 body structure, and size in text lines of the encapsulated 5619 message. 5621 A body type of type TEXT contains, immediately after the basic 5622 fields, the size of the body in text lines. Note that this 5623 size is the size in its content transfer encoding and not the 5624 resulting size after any decoding. 5626 Extension data follows the basic fields and the type-specific 5627 fields listed above. Extension data is never returned with the 5628 BODY fetch, but can be returned with a BODYSTRUCTURE fetch. 5629 Extension data, if present, MUST be in the defined order. 5631 The extension data of a non-multipart body part are in the 5632 following order: 5634 body MD5 A string giving the body MD5 value as defined in 5635 [MD5]. 5637 body disposition A parenthesized list with the same content 5638 and function as the body disposition for a multipart body 5639 part. 5641 body language A string or parenthesized list giving the body 5642 language value as defined in [LANGUAGE-TAGS]. 5644 body location A string giving the body content URI as defined 5645 in [LOCATION]. 5647 Any following extension data are not yet defined in this 5648 version of the protocol, and would be as described above under 5649 multipart extension data. 5651 ENVELOPE 5653 A parenthesized list that describes the envelope structure of a 5654 message. This is computed by the server by parsing the 5655 [RFC-5322] header into the component parts, defaulting various 5656 fields as necessary. 5658 The fields of the envelope structure are in the following 5659 order: date, subject, from, sender, reply-to, to, cc, bcc, in- 5660 reply-to, and message-id. The date, subject, in-reply-to, and 5661 message-id fields are strings. The from, sender, reply-to, to, 5662 cc, and bcc fields are parenthesized lists of address 5663 structures. 5665 An address structure is a parenthesized list that describes an 5666 electronic mail address. The fields of an address structure 5667 are in the following order: personal name, [SMTP] at-domain- 5668 list (source route, obs-route), mailbox name, and host name. 5670 [RFC-5322] group syntax is indicated by a special form of 5671 address structure in which the host name field is NIL. If the 5672 mailbox name field is also NIL, this is an end of group marker 5673 (semi-colon in RFC 822 syntax). If the mailbox name field is 5674 non-NIL, this is a start of group marker, and the mailbox name 5675 field holds the group name phrase. 5677 If the Date, Subject, In-Reply-To, and Message-ID header lines 5678 are absent in the [RFC-5322] header, the corresponding member 5679 of the envelope is NIL; if these header lines are present but 5680 empty the corresponding member of the envelope is the empty 5681 string. 5683 Note: some servers may return a NIL envelope member in the 5684 "present but empty" case. Clients SHOULD treat NIL and 5685 empty string as identical. 5687 Note: [RFC-5322] requires that all messages have a valid 5688 Date header. Therefore, for a well-formed message the date 5689 member in the envelope can not be NIL or the empty string. 5690 However it can be NIL for a malformed or a draft message. 5692 Note: [RFC-5322] requires that the In-Reply-To and Message- 5693 ID headers, if present, have non-empty content. Therefore, 5694 for a well-formed message the in-reply-to and message-id 5695 members in the envelope can not be the empty string. 5696 However they can still be the empty string for a malformed 5697 message. 5699 If the From, To, Cc, and Bcc header lines are absent in the 5700 [RFC-5322] header, or are present but empty, the corresponding 5701 member of the envelope is NIL. 5703 If the Sender or Reply-To lines are absent in the [RFC-5322] 5704 header, or are present but empty, the server sets the 5705 corresponding member of the envelope to be the same value as 5706 the from member (the client is not expected to know to do 5707 this). 5709 Note: [RFC-5322] requires that all messages have a valid 5710 From header. Therefore, for a well-formed message the from, 5711 sender, and reply-to members in the envelope can not be NIL. 5712 However they can be NIL for a malformed or a draft message. 5714 FLAGS A parenthesized list of flags that are set for this message. 5716 INTERNALDATE A string representing the internal date of the message. 5718 RFC822.SIZE A number expressing the [RFC-5322] size of the message. 5720 UID A number expressing the unique identifier of the message. 5722 If the server chooses to send unsolicited FETCH responses, they MUST 5723 include UID FETCH item. Note that this is a new requirement when 5724 compared to RFC 3501. 5726 Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827) 5728 7.5. Server Responses - Command Continuation Request 5730 The command continuation request response is indicated by a "+" token 5731 instead of a tag. This form of response indicates that the server is 5732 ready to accept the continuation of a command from the client. The 5733 remainder of this response is a line of text. 5735 This response is used in the AUTHENTICATE command to transmit server 5736 data to the client, and request additional client data. This 5737 response is also used if an argument to any command is a 5738 synchronizing literal. 5740 The client is not permitted to send the octets of the synchronizing 5741 literal unless the server indicates that it is expected. This 5742 permits the server to process commands and reject errors on a line- 5743 by-line basis. The remainder of the command, including the CRLF that 5744 terminates a command, follows the octets of the literal. If there 5745 are any additional command arguments, the literal octets are followed 5746 by a space and those arguments. 5748 Example: C: A001 LOGIN {11} 5749 S: + Ready for additional command text 5750 C: FRED FOOBAR {7} 5751 S: + Ready for additional command text 5752 C: fat man 5753 S: A001 OK LOGIN completed 5754 C: A044 BLURDYBLOOP {102856} 5755 S: A044 BAD No such command as "BLURDYBLOOP" 5757 8. Sample IMAP4rev2 connection 5759 The following is a transcript of an IMAP4rev2 connection. A long 5760 line in this sample is broken for editorial clarity. 5762 S: * OK IMAP4rev2 Service Ready 5763 C: a001 login mrc secret 5764 S: a001 OK LOGIN completed 5765 C: a002 select inbox 5766 S: * 18 EXISTS 5767 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5768 S: * OK [UIDVALIDITY 3857529045] UIDs valid 5769 S: * LIST () "/" INBOX ("OLDNAME" ("inbox")) 5770 S: a002 OK [READ-WRITE] SELECT completed 5771 C: a003 fetch 12 full 5772 S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700" 5773 RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)" 5774 "IMAP4rev2 WG mtg summary and minutes" 5775 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5776 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5777 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5778 ((NIL NIL "imap" "cac.washington.edu")) 5779 ((NIL NIL "minutes" "CNRI.Reston.VA.US") 5780 ("John Klensin" NIL "KLENSIN" "MIT.EDU")) NIL NIL 5781 "") 5782 BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 5783 92)) 5784 S: a003 OK FETCH completed 5785 C: a004 fetch 12 body[header] 5786 S: * 12 FETCH (BODY[HEADER] {342} 5787 S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT) 5788 S: From: Terry Gray 5789 S: Subject: IMAP4rev2 WG mtg summary and minutes 5790 S: To: imap@cac.washington.edu 5791 S: cc: minutes@CNRI.Reston.VA.US, John Klensin 5792 S: Message-Id: 5793 S: MIME-Version: 1.0 5794 S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 5795 S: 5796 S: ) 5797 S: a004 OK FETCH completed 5798 C: a005 store 12 +flags \deleted 5799 S: * 12 FETCH (FLAGS (\Seen \Deleted)) 5800 S: a005 OK +FLAGS completed 5801 C: a006 logout 5802 S: * BYE IMAP4rev2 server terminating connection 5803 S: a006 OK LOGOUT completed 5805 9. Formal Syntax 5807 The following syntax specification uses the Augmented Backus-Naur 5808 Form (ABNF) notation as specified in [ABNF]. 5810 In the case of alternative or optional rules in which a later rule 5811 overlaps an earlier rule, the rule which is listed earlier MUST take 5812 priority. For example, "\Seen" when parsed as a flag is the \Seen 5813 flag name and not a flag-extension, even though "\Seen" can be parsed 5814 as a flag-extension. Some, but not all, instances of this rule are 5815 noted below. 5817 Note: [ABNF] rules MUST be followed strictly; in particular: 5819 (1) Except as noted otherwise, all alphabetic characters are case- 5820 insensitive. The use of upper or lower case characters to define 5821 token strings is for editorial clarity only. Implementations MUST 5822 accept these strings in a case-insensitive fashion. 5824 (2) In all cases, SP refers to exactly one space. It is NOT 5825 permitted to substitute TAB, insert additional spaces, or 5826 otherwise treat SP as being equivalent to LWSP. 5828 (3) The ASCII NUL character, %x00, MUST NOT be used at any time. 5830 address = "(" addr-name SP addr-adl SP addr-mailbox SP 5831 addr-host ")" 5833 addr-adl = nstring 5834 ; Holds route from [RFC-5322] obs-route if 5835 ; non-NIL 5837 addr-host = nstring 5838 ; NIL indicates [RFC-5322] group syntax. 5839 ; Otherwise, holds [RFC-5322] domain name 5841 addr-mailbox = nstring 5842 ; NIL indicates end of [RFC-5322] group; if 5843 ; non-NIL and addr-host is NIL, holds 5844 ; [RFC-5322] group name. 5845 ; Otherwise, holds [RFC-5322] local-part 5846 ; after removing [RFC-5322] quoting 5848 addr-name = nstring 5849 ; If non-NIL, holds phrase from [RFC-5322] 5850 ; mailbox after removing [RFC-5322] quoting 5852 append = "APPEND" SP mailbox [SP flag-list] [SP date-time] SP 5853 literal 5855 append-uid = uniqueid 5857 astring = 1*ASTRING-CHAR / string 5858 ASTRING-CHAR = ATOM-CHAR / resp-specials 5860 atom = 1*ATOM-CHAR 5862 ATOM-CHAR = 5864 atom-specials = "(" / ")" / "{" / SP / CTL / list-wildcards / 5865 quoted-specials / resp-specials 5867 authenticate = "AUTHENTICATE" SP auth-type [SP initial-resp] 5868 *(CRLF base64) 5870 auth-type = atom 5871 ; Defined by [SASL] 5873 base64 = *(4base64-char) [base64-terminal] 5875 base64-char = ALPHA / DIGIT / "+" / "/" 5876 ; Case-sensitive 5878 base64-terminal = (2base64-char "==") / (3base64-char "=") 5880 body = "(" (body-type-1part / body-type-mpart) ")" 5882 body-extension = nstring / number / 5883 "(" body-extension *(SP body-extension) ")" 5884 ; Future expansion. Client implementations 5885 ; MUST accept body-extension fields. Server 5886 ; implementations MUST NOT generate 5887 ; body-extension fields except as defined by 5888 ; future standard or standards-track 5889 ; revisions of this specification. 5891 body-ext-1part = body-fld-md5 [SP body-fld-dsp [SP body-fld-lang 5892 [SP body-fld-loc *(SP body-extension)]]] 5893 ; MUST NOT be returned on non-extensible 5894 ; "BODY" fetch 5896 body-ext-mpart = body-fld-param [SP body-fld-dsp [SP body-fld-lang 5897 [SP body-fld-loc *(SP body-extension)]]] 5898 ; MUST NOT be returned on non-extensible 5899 ; "BODY" fetch 5901 body-fields = body-fld-param SP body-fld-id SP body-fld-desc SP 5902 body-fld-enc SP body-fld-octets 5904 body-fld-desc = nstring 5905 body-fld-dsp = "(" string SP body-fld-param ")" / nil 5907 body-fld-enc = (DQUOTE ("7BIT" / "8BIT" / "BINARY" / "BASE64"/ 5908 "QUOTED-PRINTABLE") DQUOTE) / string 5909 ; Content-Transfer-Encoding header field value. 5910 ; Defaults to "7BIT" (as per RFC 2045) 5911 ; if not present in the body part. 5913 body-fld-id = nstring 5915 body-fld-lang = nstring / "(" string *(SP string) ")" 5917 body-fld-loc = nstring 5919 body-fld-lines = number 5921 body-fld-md5 = nstring 5923 body-fld-octets = number 5925 body-fld-param = "(" string SP string *(SP string SP string) ")" / nil 5927 body-type-1part = (body-type-basic / body-type-msg / body-type-text) 5928 [SP body-ext-1part] 5930 body-type-basic = media-basic SP body-fields 5931 ; MESSAGE subtype MUST NOT be "RFC822" or "GLOBAL" 5933 body-type-mpart = 1*body SP media-subtype 5934 [SP body-ext-mpart] 5935 ; MULTIPART body part 5937 body-type-msg = media-message SP body-fields SP envelope 5938 SP body SP body-fld-lines 5940 body-type-text = media-text SP body-fields SP body-fld-lines 5942 capability = ("AUTH=" auth-type) / atom 5943 ; New capabilities MUST begin with "X" or be 5944 ; registered with IANA in 5945 ; a standards-track, an experimental 5946 ; or an informational RFC. 5948 capability-data = "CAPABILITY" *(SP capability) SP "IMAP4rev2" 5949 *(SP capability) 5950 ; Servers MUST implement the STARTTLS, AUTH=PLAIN, 5951 ; and LOGINDISABLED capabilities. 5952 ; Servers which offer RFC 1730 compatibility MUST 5953 ; list "IMAP4" as the first capability. 5954 ; Servers which offer RFC 3501 compatibility MUST 5955 ; list "IMAP4rev1" as one of capabilities. 5957 CHAR = 5959 CHAR8 = %x01-ff 5960 ; any OCTET except NUL, %x00 5962 charset = atom / quoted 5964 childinfo-extended-item = "CHILDINFO" SP "(" 5965 list-select-base-opt-quoted 5966 *(SP list-select-base-opt-quoted) ")" 5967 ; Extended data item (mbox-list-extended-item) 5968 ; returned when the RECURSIVEMATCH 5969 ; selection option is specified. 5970 ; Note 1: the CHILDINFO extended data item tag can be 5971 ; returned with and without surrounding quotes, as per 5972 ; mbox-list-extended-item-tag production. 5973 ; Note 2: The selection options are always returned 5974 ; quoted, unlike their specification in 5975 ; the extended LIST command. 5977 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 5978 ; attributes for CHILDREN return option, at most one 5979 ; possible per LIST response 5981 command = tag SP (command-any / command-auth / command-nonauth / 5982 command-select) CRLF 5983 ; Modal based on state 5985 command-any = "CAPABILITY" / "LOGOUT" / "NOOP" / enable / x-command 5986 ; Valid in all states 5988 command-auth = append / create / delete / examine / list / 5989 Namespace-Command / 5990 rename / select / status / subscribe / unsubscribe / 5991 idle 5992 ; Valid only in Authenticated or Selected state 5994 command-nonauth = login / authenticate / "STARTTLS" 5995 ; Valid only when in Not Authenticated state 5997 command-select = "CLOSE" / "UNSELECT" / "EXPUNGE" / copy / 5998 move / fetch / store / search / uid 5999 ; Valid only when in Selected state 6001 continue-req = "+" SP (resp-text / base64) CRLF 6003 copy = "COPY" SP sequence-set SP mailbox 6005 create = "CREATE" SP mailbox 6006 ; Use of INBOX gives a NO error 6008 date = date-text / DQUOTE date-text DQUOTE 6010 date-day = 1*2DIGIT 6011 ; Day of month 6013 date-day-fixed = (SP DIGIT) / 2DIGIT 6014 ; Fixed-format version of date-day 6016 date-month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / 6017 "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" 6019 date-text = date-day "-" date-month "-" date-year 6021 date-year = 4DIGIT 6023 date-time = DQUOTE date-day-fixed "-" date-month "-" date-year 6024 SP time SP zone DQUOTE 6026 delete = "DELETE" SP mailbox 6027 ; Use of INBOX gives a NO error 6029 digit-nz = %x31-39 6030 ; 1-9 6032 eitem-standard-tag = atom 6033 ; a tag for LIST extended data item defined in a Standard 6034 ; Track or Experimental RFC. 6036 eitem-vendor-tag = vendor-token "-" atom 6037 ; a vendor-specific tag for LIST extended data item 6039 enable = "ENABLE" 1*(SP capability) 6041 enable-data = "ENABLED" *(SP capability) 6043 envelope = "(" env-date SP env-subject SP env-from SP 6044 env-sender SP env-reply-to SP env-to SP env-cc SP 6045 env-bcc SP env-in-reply-to SP env-message-id ")" 6047 env-bcc = "(" 1*address ")" / nil 6048 env-cc = "(" 1*address ")" / nil 6050 env-date = nstring 6052 env-from = "(" 1*address ")" / nil 6054 env-in-reply-to = nstring 6056 env-message-id = nstring 6058 env-reply-to = "(" 1*address ")" / nil 6060 env-sender = "(" 1*address ")" / nil 6062 env-subject = nstring 6064 env-to = "(" 1*address ")" / nil 6066 esearch-response = "ESEARCH" [search-correlator] [SP "UID"] 6067 *(SP search-return-data) 6068 ; ESEARCH response replaces SEARCH response 6069 ; from IMAP4rev1. 6071 examine = "EXAMINE" SP mailbox 6073 fetch = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" / 6074 fetch-att / "(" fetch-att *(SP fetch-att) ")") 6076 fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" / 6077 "RFC822.SIZE" / 6078 "BODY" ["STRUCTURE"] / "UID" / 6079 "BODY" section [partial] / 6080 "BODY.PEEK" section [partial] / 6081 "BINARY" [".PEEK"] section-binary [partial] / 6082 "BINARY.SIZE" section-binary 6084 flag = "\Answered" / "\Flagged" / "\Deleted" / 6085 "\Seen" / "\Draft" / flag-keyword / flag-extension 6086 ; Does not include "\Recent" 6088 flag-extension = "\" atom 6089 ; Future expansion. Client implementations 6090 ; MUST accept flag-extension flags. Server 6091 ; implementations MUST NOT generate 6092 ; flag-extension flags except as defined by 6093 ; future standard or standards-track 6094 ; revisions of this specification. 6095 ; "\Recent" was defined in RFC 3501 6096 ; and is now deprecated. 6098 flag-fetch = flag 6100 flag-keyword = "$MDNSent" / "$Forwarded" / "$Junk" / 6101 "$NotJunk" / "$Phishing" / atom 6103 flag-list = "(" [flag *(SP flag)] ")" 6105 flag-perm = flag / "\*" 6107 greeting = "*" SP (resp-cond-auth / resp-cond-bye) CRLF 6109 header-fld-name = astring 6111 header-list = "(" header-fld-name *(SP header-fld-name) ")" 6113 idle = "IDLE" CRLF "DONE" 6115 initial-resp = (base64 / "=") 6116 ; "initial response" defined in 6117 ; Section 5.1 of [RFC4422] 6119 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 6120 [SP list-return-opts] 6122 list-mailbox = 1*list-char / string 6124 list-char = ATOM-CHAR / list-wildcards / resp-specials 6126 list-return-opts = "RETURN" SP 6127 "(" [return-option *(SP return-option)] ")" 6128 ; list return options, e.g., CHILDREN 6130 list-select-base-opt = "SUBSCRIBED" / option-extension 6131 ; options that can be used by themselves 6133 list-select-base-opt-quoted = DQUOTE list-select-base-opt DQUOTE 6135 list-select-independent-opt = "REMOTE" / option-extension 6136 ; options that do not syntactically interact with 6137 ; other options 6139 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 6140 ; options that require a list-select-base-opt 6141 ; to also be present 6143 list-select-opt = list-select-base-opt / list-select-independent-opt 6144 / list-select-mod-opt 6145 ; An option registration template is described in 6146 ; Section 9.3 of this document. 6148 list-select-opts = "(" [ 6149 (*(list-select-opt SP) list-select-base-opt 6150 *(SP list-select-opt)) 6151 / (list-select-independent-opt 6152 *(SP list-select-independent-opt)) 6153 ] ")" 6154 ; Any number of options may be in any order. 6155 ; If a list-select-mod-opt appears, then a 6156 ; list-select-base-opt must also appear. 6157 ; This allows these: 6158 ; () 6159 ; (REMOTE) 6160 ; (SUBSCRIBED) 6161 ; (SUBSCRIBED REMOTE) 6162 ; (SUBSCRIBED RECURSIVEMATCH) 6163 ; (SUBSCRIBED REMOTE RECURSIVEMATCH) 6164 ; But does NOT allow these: 6165 ; (RECURSIVEMATCH) 6166 ; (REMOTE RECURSIVEMATCH) 6168 list-wildcards = "%" / "*" 6170 literal = "{" number ["+"] "}" CRLF *CHAR8 6171 ; represents the number of CHAR8s. 6172 ; A non-synchronizing literal is distinguished from 6173 ; a synchronizing literal by presence of the "+" 6174 ; before the closing "}". 6175 ; Non synchronizing literals are not allowed when 6176 ; sent from server to the client. 6178 literal8 = "~{" number "}" CRLF *OCTET 6179 ; represents the number of OCTETs 6180 ; in the response string. 6182 login = "LOGIN" SP userid SP password 6184 mailbox = "INBOX" / astring 6185 ; INBOX is case-insensitive. All case variants of 6186 ; INBOX (e.g., "iNbOx") MUST be interpreted as INBOX 6187 ; not as an astring. An astring which consists of 6188 ; the case-insensitive sequence "I" "N" "B" "O" "X" 6189 ; is considered to be INBOX and not an astring. 6190 ; Refer to section 5.1 for further 6191 ; semantic details of mailbox names. 6193 mailbox-data = "FLAGS" SP flag-list / "LIST" SP mailbox-list / 6194 esearch-response / 6195 "STATUS" SP mailbox SP "(" [status-att-list] ")" / 6196 number SP "EXISTS" / Namespace-Response 6198 mailbox-list = "(" [mbx-list-flags] ")" SP 6199 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 6200 [SP mbox-list-extended] 6201 ; This is the list information pointed to by the ABNF 6202 ; item "mailbox-data", which is defined in [IMAP4] 6204 mbox-list-extended = "(" [mbox-list-extended-item 6205 *(SP mbox-list-extended-item)] ")" 6207 mbox-list-extended-item = mbox-list-extended-item-tag SP 6208 tagged-ext-val 6210 mbox-list-extended-item-tag = astring 6211 ; The content MUST conform to either "eitem-vendor-tag" 6212 ; or "eitem-standard-tag" ABNF productions. 6214 mbox-or-pat = list-mailbox / patterns 6216 mbx-list-flags = *(mbx-list-oflag SP) mbx-list-sflag 6217 *(SP mbx-list-oflag) / 6218 mbx-list-oflag *(SP mbx-list-oflag) 6220 mbx-list-oflag = "\Noinferiors" / child-mbox-flag / 6221 "\Subscribed" / "\Remote" / flag-extension 6222 ; Other flags; multiple possible per LIST response 6224 mbx-list-sflag = "\NonExistent" / "\Noselect" / "\Marked" / "\Unmarked" 6225 ; Selectability flags; only one per LIST response 6227 media-basic = ((DQUOTE ("APPLICATION" / "AUDIO" / "IMAGE" / 6228 "FONT" / "MESSAGE" / "MODEL" / "VIDEO" ) DQUOTE) 6229 / string) 6230 SP media-subtype 6231 ; Defined in [MIME-IMT]. 6232 ; FONT defined in RFC 8081. 6234 media-message = DQUOTE "MESSAGE" DQUOTE SP 6235 DQUOTE ("RFC822" / "GLOBAL") DQUOTE 6236 ; Defined in [MIME-IMT] 6238 media-subtype = string 6239 ; Defined in [MIME-IMT] 6241 media-text = DQUOTE "TEXT" DQUOTE SP media-subtype 6242 ; Defined in [MIME-IMT] 6244 message-data = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att)) 6246 move = "MOVE" SP sequence-set SP mailbox 6248 msg-att = "(" (msg-att-dynamic / msg-att-static) 6249 *(SP (msg-att-dynamic / msg-att-static)) ")" 6251 msg-att-dynamic = "FLAGS" SP "(" [flag-fetch *(SP flag-fetch)] ")" 6252 ; MAY change for a message 6254 msg-att-static = "ENVELOPE" SP envelope / "INTERNALDATE" SP date-time / 6255 "RFC822.SIZE" SP number / 6256 "BODY" ["STRUCTURE"] SP body / 6257 "BODY" section ["<" number ">"] SP nstring / 6258 "BINARY" section-binary SP (nstring / literal8) / 6259 "BINARY.SIZE" section-binary SP number / 6260 "UID" SP uniqueid 6261 ; MUST NOT change for a message 6263 name-component = 1*UTF8-CHAR 6264 ; MUST NOT contain ".", "/", "%", or "*" 6266 Namespace = nil / "(" 1*Namespace-Descr ")" 6268 Namespace-Command = "NAMESPACE" 6270 Namespace-Descr = "(" string SP 6271 (DQUOTE QUOTED-CHAR DQUOTE / nil) 6272 [Namespace-Response-Extensions] ")" 6274 Namespace-Response-Extensions = *Namespace-Response-Extension 6276 Namespace-Response-Extension = SP string SP 6277 "(" string *(SP string) ")" 6279 Namespace-Response = "NAMESPACE" SP Namespace 6280 SP Namespace SP Namespace 6281 ; The first Namespace is the Personal Namespace(s). 6282 ; The second Namespace is the Other Users' 6283 ; Namespace(s). 6284 ; The third Namespace is the Shared Namespace(s). 6286 nil = "NIL" 6287 nstring = string / nil 6289 number = 1*DIGIT 6290 ; Unsigned 32-bit integer 6291 ; (0 <= n < 4,294,967,296) 6293 number64 = 1*DIGIT 6294 ; Unsigned 63-bit integer 6295 ; (0 <= n <= 9,223,372,036,854,775,807) 6297 nz-number = digit-nz *DIGIT 6298 ; Non-zero unsigned 32-bit integer 6299 ; (0 < n < 4,294,967,296) 6301 oldname-extended-item = "OLDNAME" SP "(" mailbox ")" 6302 ; Extended data item (mbox-list-extended-item) 6303 ; returned in a LIST response when a mailbox is 6304 ; renamed or deleted. Also returned when 6305 ; the server canonicalized the provided mailbox 6306 ; name. 6307 ; Note 1: the OLDNAME tag can be returned 6308 ; with or without surrounding quotes, as per 6309 ; mbox-list-extended-item-tag production. 6311 option-extension = (option-standard-tag / option-vendor-tag) 6312 [SP option-value] 6314 option-standard-tag = atom 6315 ; an option defined in a Standards Track or 6316 ; Experimental RFC 6318 option-val-comp = astring / 6319 option-val-comp *(SP option-val-comp) / 6320 "(" option-val-comp ")" 6322 option-value = "(" option-val-comp ")" 6324 option-vendor-tag = vendor-token "-" atom 6325 ; a vendor-specific option, non-standard 6327 partial-range = number ["." nz-number] 6328 ; Copied from RFC 5092 (IMAP URL) 6330 partial = "<" number "." nz-number ">" 6331 ; Partial FETCH request. 0-based offset of 6332 ; the first octet, followed by the number of octets 6333 ; in the fragment. 6335 password = astring 6337 patterns = "(" list-mailbox ")" 6338 ; [RFC5258] supports multiple patterns, 6339 ; but this document only requires one 6340 ; to be supported. 6341 ; If the server is also implementing 6342 ; [RFC5258], "patterns" syntax from that 6343 ; document must be followed. 6345 quoted = DQUOTE *QUOTED-CHAR DQUOTE 6347 QUOTED-CHAR = / 6348 "\" quoted-specials / UTF8-2 / UTF8-3 / UTF8-4 6350 quoted-specials = DQUOTE / "\" 6352 rename = "RENAME" SP mailbox SP mailbox 6353 ; Use of INBOX as a destination gives a NO error 6355 response = *(continue-req / response-data) response-done 6357 response-data = "*" SP (resp-cond-state / resp-cond-bye / 6358 mailbox-data / message-data / capability-data / 6359 enable-data) CRLF 6361 response-done = response-tagged / response-fatal 6363 response-fatal = "*" SP resp-cond-bye CRLF 6364 ; Server closes connection immediately 6366 response-tagged = tag SP resp-cond-state CRLF 6368 resp-code-apnd = "APPENDUID" SP nz-number SP append-uid 6370 resp-code-copy = "COPYUID" SP nz-number SP uid-set SP uid-set 6372 resp-cond-auth = ("OK" / "PREAUTH") SP resp-text 6373 ; Authentication condition 6375 resp-cond-bye = "BYE" SP resp-text 6377 resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text 6378 ; Status condition 6380 resp-specials = "]" 6382 resp-text = ["[" resp-text-code "]" SP] [text] 6383 resp-text-code = "ALERT" / 6384 "BADCHARSET" [SP "(" charset *(SP charset) ")" ] / 6385 capability-data / "PARSE" / 6386 "PERMANENTFLAGS" SP 6387 "(" [flag-perm *(SP flag-perm)] ")" / 6388 "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / 6389 "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number / 6390 resp-code-apnd / resp-code-copy / "UIDNOTSTICKY" / 6391 "UNAVAILABLE" / "AUTHENTICATIONFAILED" / 6392 "AUTHORIZATIONFAILED" / "EXPIRED" / 6393 "PRIVACYREQUIRED" / "CONTACTADMIN" / "NOPERM" / 6394 "INUSE" / "EXPUNGEISSUED" / "CORRUPTION" / 6395 "SERVERBUG" / "CLIENTBUG" / "CANNOT" / 6396 "LIMIT" / "OVERQUOTA" / "ALREADYEXISTS" / 6397 "NONEXISTENT" / "NOTSAVED" / "HASCHILDREN" / 6398 "CLOSED" / 6399 "UNKNOWN-CTE" / 6400 atom [SP 1*] 6402 return-option = "SUBSCRIBED" / "CHILDREN" / status-option / 6403 option-extension 6405 search = "SEARCH" [search-return-opts] 6406 SP search-program 6408 search-correlator = SP "(" "TAG" SP tag-string ")" 6410 search-key = "ALL" / "ANSWERED" / "BCC" SP astring / 6411 "BEFORE" SP date / "BODY" SP astring / 6412 "CC" SP astring / "DELETED" / "FLAGGED" / 6413 "FROM" SP astring / "KEYWORD" SP flag-keyword / 6414 "ON" SP date / "SEEN" / 6415 "SINCE" SP date / "SUBJECT" SP astring / 6416 "TEXT" SP astring / "TO" SP astring / 6417 "UNANSWERED" / "UNDELETED" / "UNFLAGGED" / 6418 "UNKEYWORD" SP flag-keyword / "UNSEEN" / 6419 ; Above this line were in [IMAP2] 6420 "DRAFT" / "HEADER" SP header-fld-name SP astring / 6421 "LARGER" SP number / "NOT" SP search-key / 6422 "OR" SP search-key SP search-key / 6423 "SENTBEFORE" SP date / "SENTON" SP date / 6424 "SENTSINCE" SP date / "SMALLER" SP number / 6425 "UID" SP sequence-set / "UNDRAFT" / sequence-set / 6426 "(" search-key *(SP search-key) ")" 6428 search-modifier-name = tagged-ext-label 6430 search-mod-params = tagged-ext-val 6431 ; This non-terminal shows recommended syntax 6432 ; for future extensions. 6434 search-program = ["CHARSET" SP charset SP] 6435 search-key *(SP search-key) 6436 ; CHARSET argument to SEARCH MUST be 6437 ; registered with IANA. 6439 search-ret-data-ext = search-modifier-name SP search-return-value 6440 ; Note that not every SEARCH return option 6441 ; is required to have the corresponding 6442 ; ESEARCH return data. 6444 search-return-data = "MIN" SP nz-number / 6445 "MAX" SP nz-number / 6446 "ALL" SP sequence-set / 6447 "COUNT" SP number / 6448 search-ret-data-ext 6449 ; All return data items conform to 6450 ; search-ret-data-ext syntax. 6451 ; Note that "$" marker is not allowed 6452 ; after the ALL return data item. 6454 search-return-opts = SP "RETURN" SP "(" [search-return-opt 6455 *(SP search-return-opt)] ")" 6457 search-return-opt = "MIN" / "MAX" / "ALL" / "COUNT" / 6458 "SAVE" / 6459 search-ret-opt-ext 6460 ; conforms to generic search-ret-opt-ext 6461 ; syntax 6463 search-ret-opt-ext = search-modifier-name [SP search-mod-params] 6465 search-return-value = tagged-ext-val 6466 ; Data for the returned search option. 6467 ; A single "nz-number"/"number"/"number64" value 6468 ; can be returned as an atom (i.e., without 6469 ; quoting). A sequence-set can be returned 6470 ; as an atom as well. 6472 section = "[" [section-spec] "]" 6474 section-binary = "[" [section-part] "]" 6476 section-msgtext = "HEADER" / "HEADER.FIELDS" [".NOT"] SP header-list / 6477 "TEXT" 6478 ; top-level or MESSAGE/RFC822 or MESSAGE/GLOBAL part 6480 section-part = nz-number *("." nz-number) 6481 ; body part reference. 6482 ; Allows for accessing nested body parts. 6484 section-spec = section-msgtext / (section-part ["." section-text]) 6486 section-text = section-msgtext / "MIME" 6487 ; text other than actual body part (headers, etc.) 6489 select = "SELECT" SP mailbox 6491 seq-number = nz-number / "*" 6492 ; message sequence number (COPY, FETCH, STORE 6493 ; commands) or unique identifier (UID COPY, 6494 ; UID FETCH, UID STORE commands). 6495 ; * represents the largest number in use. In 6496 ; the case of message sequence numbers, it is 6497 ; the number of messages in a non-empty mailbox. 6498 ; In the case of unique identifiers, it is the 6499 ; unique identifier of the last message in the 6500 ; mailbox or, if the mailbox is empty, the 6501 ; mailbox's current UIDNEXT value. 6502 ; The server should respond with a tagged BAD 6503 ; response to a command that uses a message 6504 ; sequence number greater than the number of 6505 ; messages in the selected mailbox. This 6506 ; includes "*" if the selected mailbox is empty. 6508 seq-range = seq-number ":" seq-number 6509 ; two seq-number values and all values between 6510 ; these two regardless of order. 6511 ; Example: 2:4 and 4:2 are equivalent and indicate 6512 ; values 2, 3, and 4. 6513 ; Example: a unique identifier sequence range of 6514 ; 3291:* includes the UID of the last message in 6515 ; the mailbox, even if that value is less than 3291. 6517 sequence-set = (seq-number / seq-range) ["," sequence-set] 6518 ; set of seq-number values, regardless of order. 6519 ; Servers MAY coalesce overlaps and/or execute the 6520 ; sequence in any order. 6521 ; Example: a message sequence number set of 6522 ; 2,4:7,9,12:* for a mailbox with 15 messages is 6523 ; equivalent to 2,4,5,6,7,9,12,13,14,15 6524 ; Example: a message sequence number set of *:4,5:7 6525 ; for a mailbox with 10 messages is equivalent to 6526 ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and 6527 ; overlap coalesced to be 4,5,6,7,8,9,10. 6529 sequence-set =/ seq-last-command 6530 ; Allow for "result of the last command" indicator. 6532 seq-last-command = "$" 6534 status = "STATUS" SP mailbox SP 6535 "(" status-att *(SP status-att) ")" 6537 status-att = "MESSAGES" / "UIDNEXT" / "UIDVALIDITY" / 6538 "UNSEEN" / "DELETED" / "SIZE" 6540 status-att-val = ("MESSAGES" SP number) / 6541 ("UIDNEXT" SP nz-number) / 6542 ("UIDVALIDITY" SP nz-number) / 6543 ("UNSEEN" SP number) / 6544 ("DELETED" SP number) / 6545 ("SIZE" SP number64) 6546 ; Extensions to the STATUS responses 6547 ; should extend this production. 6548 ; Extensions should use the generic 6549 ; syntax defined by tagged-ext. 6551 status-att-list = status-att-val *(SP status-att-val) 6553 status-option = "STATUS" SP "(" status-att *(SP status-att) ")" 6554 ; This ABNF production complies with 6555 ; syntax. 6557 store = "STORE" SP sequence-set SP store-att-flags 6559 store-att-flags = (["+" / "-"] "FLAGS" [".SILENT"]) SP 6560 (flag-list / (flag *(SP flag))) 6562 string = quoted / literal 6564 subscribe = "SUBSCRIBE" SP mailbox 6566 tag = 1* 6568 tag-string = astring 6569 ; represented as 6571 tagged-ext-label = tagged-label-fchar *tagged-label-char 6572 ; Is a valid RFC 3501 "atom". 6574 tagged-label-fchar = ALPHA / "-" / "_" / "." 6576 tagged-label-char = tagged-label-fchar / DIGIT / ":" 6577 tagged-ext-comp = astring / 6578 tagged-ext-comp *(SP tagged-ext-comp) / 6579 "(" tagged-ext-comp ")" 6580 ; Extensions that follow this general 6581 ; syntax should use nstring instead of 6582 ; astring when appropriate in the context 6583 ; of the extension. 6584 ; Note that a message set or a "number" 6585 ; can always be represented as an "atom". 6586 ; An URL should be represented as 6587 ; a "quoted" string. 6589 tagged-ext-simple = sequence-set / number / number64 6591 tagged-ext-val = tagged-ext-simple / 6592 "(" [tagged-ext-comp] ")" 6594 text = 1*(TEXT-CHAR / UTF8-2 / UTF8-3 / UTF8-4) 6595 ; Non ASCII text can only be returned 6596 ; after ENABLE IMAP4rev2 command 6598 TEXT-CHAR = 6600 time = 2DIGIT ":" 2DIGIT ":" 2DIGIT 6601 ; Hours minutes seconds 6603 uid = "UID" SP 6604 (copy / move / fetch / search / store / uid-expunge) 6605 ; Unique identifiers used instead of message 6606 ; sequence numbers 6608 uid-expunge = "EXPUNGE" SP sequence-set 6609 ; Unique identifiers used instead of message 6610 ; sequence numbers 6612 uid-set = (uniqueid / uid-range) *("," uid-set) 6614 uid-range = (uniqueid ":" uniqueid) 6615 ; two uniqueid values and all values 6616 ; between these two regards of order. 6617 ; Example: 2:4 and 4:2 are equivalent. 6619 uniqueid = nz-number 6620 ; Strictly ascending 6622 unsubscribe = "UNSUBSCRIBE" SP mailbox 6624 userid = astring 6625 UTF8-2 = 6627 UTF8-3 = 6629 UTF8-4 = 6631 vendor-token = "vendor." name-component 6632 ; Definition copied from RFC 2244. 6633 ; MUST be registered with IANA 6635 x-command = "X" atom 6637 zone = ("+" / "-") 4DIGIT 6638 ; Signed four-digit value of hhmm representing 6639 ; hours and minutes east of Greenwich (that is, 6640 ; the amount that the given time differs from 6641 ; Universal Time). Subtracting the timezone 6642 ; from the given time will give the UT form. 6643 ; The Universal Time zone is "+0000". 6645 10. Author's Note 6647 This document is a revision or rewrite of earlier documents, and 6648 supercedes the protocol specification in those documents: RFC 3501, 6649 RFC 2060, RFC 1730, unpublished IMAP2bis.TXT document, RFC 1176, and 6650 RFC 1064. 6652 11. Security Considerations 6654 IMAP4rev2 protocol transactions, including electronic mail data, are 6655 sent in the clear over the network unless protection from snooping is 6656 negotiated. This can be accomplished either by the use of IMAPS 6657 service, STARTTLS command, negotiated privacy protection in the 6658 AUTHENTICATE command, or some other protection mechanism. 6660 11.1. STARTTLS Security Considerations 6662 IMAP client and server implementations MUST comply with relevant TLS 6663 recommendations from [RFC8314]. 6665 Clients and servers MUST implement TLS 1.2 or newer. Use of TLS 1.3 6666 [TLS-1.3] is RECOMMENDED. However [TLS-1.2] MAY be used. 6667 Additionally, when using TLS 1.2, IMAP implementations MUST implement 6668 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite, and SHOULD 6669 implement the TLS_RSA_WITH_AES_128_CBC_SHA [TLS-1.2] cipher suite. 6670 This is important as it assures that any two compliant 6671 implementations can be configured to interoperate. Other TLS cipher 6672 suites recommended in RFC 7525 are RECOMMENDED: 6674 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 6675 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 and 6676 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384. All other cipher suites are 6677 OPTIONAL. Note that this is a change from section 2.1 of [IMAP-TLS]. 6679 The list of mandatory-to-implement TLS 1.3 cipher suites is described 6680 in Section 9.1 of [TLS-1.3]. 6682 During the TLS negotiation [TLS-1.3][TLS-1.2], the client MUST check 6683 its understanding of the server hostname against the server's 6684 identity as presented in the server Certificate message, in order to 6685 prevent man-in-the-middle attacks. This procedure is described in 6686 [RFC7817]. 6688 Both the client and server MUST check the result of the STARTTLS 6689 command and subsequent TLS ([TLS-1.3][TLS-1.2]) negotiation to see 6690 whether acceptable authentication and/or privacy was achieved. 6692 11.2. COPYUID and APPENDUID response codes 6694 The COPYUID and APPENDUID response codes return information about the 6695 mailbox, which may be considered sensitive if the mailbox has 6696 permissions set that permit the client to COPY or APPEND to the 6697 mailbox, but not SELECT or EXAMINE it. 6699 Consequently, these response codes SHOULD NOT be issued if the client 6700 does not have access to SELECT or EXAMINE the mailbox. 6702 11.3. LIST command and Other Users' namespace 6704 In response to a LIST command containing an argument of the Other 6705 Users' Namespace prefix, a server SHOULD NOT list users that have not 6706 granted list access to their personal mailboxes to the currently 6707 authenticated user. Providing such a list, could compromise security 6708 by potentially disclosing confidential information of who is located 6709 on the server, or providing a starting point of a list of user 6710 accounts to attack. 6712 11.4. Other Security Considerations 6714 A server error message for an AUTHENTICATE command which fails due to 6715 invalid credentials SHOULD NOT detail why the credentials are 6716 invalid. 6718 Use of the LOGIN command sends passwords in the clear. This can be 6719 avoided by using the AUTHENTICATE command with a [SASL] mechanism 6720 that does not use plaintext passwords, by first negotiating 6721 encryption via STARTTLS or some other protection mechanism. 6723 A server implementation MUST implement a configuration that, at the 6724 time of authentication, requires: 6725 (1) The STARTTLS command has been negotiated. 6726 OR 6727 (2) Some other mechanism that protects the session from password 6728 snooping has been provided. 6729 OR 6730 (3) The following measures are in place: 6731 (a) The LOGINDISABLED capability is advertised, and [SASL] mechanisms 6732 (such as PLAIN) using plaintext passwords are NOT advertised in the 6733 CAPABILITY list. 6734 AND 6735 (b) The LOGIN command returns an error even if the password is 6736 correct. 6737 AND 6738 (c) The AUTHENTICATE command returns an error with all [SASL] 6739 mechanisms that use plaintext passwords, even if the password is 6740 correct. 6742 A server error message for a failing LOGIN command SHOULD NOT specify 6743 that the user name, as opposed to the password, is invalid. 6745 A server SHOULD have mechanisms in place to limit or delay failed 6746 AUTHENTICATE/LOGIN attempts. 6748 Additional security considerations are discussed in the section 6749 discussing the AUTHENTICATE (see Section 6.2.2) and LOGIN (see 6750 Section 6.2.3) commands. 6752 12. IANA Considerations 6754 IANA is requested to update "Service Names and Transport Protocol 6755 Port Numbers" registry as follows: 6757 1. Registration for TCP port 143 and the corresponding "imap" 6758 service name should be updated to point to this document and RFC 6759 3501. 6761 2. Registration for TCP port 993 and the corresponding "imaps" 6762 service name should be updated to point to this document, RFC 6763 8314 and RFC 3501. 6765 3. Both UDP port 143 and UDP port 993 should be marked as "Reserved" 6766 in the registry. 6768 Additional IANA actions are specified in subsection of this section. 6770 12.1. Updates to IMAP4 Capabilities registry 6772 IMAP4 capabilities are registered by publishing a standards track or 6773 IESG approved informational or experimental RFC. The registry is 6774 currently located at: https://www.iana.org/assignments/ 6775 imap4-capabilities 6777 As this specification revises the AUTH= prefix, STARTTLS and 6778 LOGINDISABLED extensions, IANA is requested to update registry 6779 entries for these 3 extensions to point to this document. 6781 12.2. GSSAPI/SASL service name 6783 GSSAPI/Kerberos/SASL service names are registered by publishing a 6784 standards track or IESG approved experimental RFC. The registry is 6785 currently located at: https://www.iana.org/assignments/gssapi- 6786 service-names 6788 IANA is requested to update the "imap" service name previously 6789 registered in RFC 3501, to point to this document. 6791 12.3. LIST Selection Options, LIST Return Options, LIST extended data 6792 items 6794 [RFC5258] specifies IANA registration procedures for LIST Selection 6795 Options, LIST Return Options, LIST extended data items. This 6796 document doesn't change these registration procedures. In particular 6797 LIST selection options Section 6.3.9.1 and LIST return options 6798 Section 6.3.9.2 are registered using the procedure specified in 6799 Section 9 of [RFC5258] (and using the registration template from 6800 Section 9.3 of [RFC5258]). LIST Extended Data Items are registered 6801 using the registration template from Section 9.6 of [RFC5258]). 6803 IANA is requested to add a reference to [RFCXXXX] for the "OLDNAME" 6804 LIST-EXTENDED extended data item entry. This is in addition to the 6805 existing reference to [RFC5465]. 6807 13. References 6809 13.1. Normative References 6811 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access 6812 Protocol version 4 - LIST Command Extensions", RFC 5258, 6813 DOI 10.17487/RFC5258, June 2008, 6814 . 6816 [RFC5788] Melnikov, A. and D. Cridland, "IMAP4 Keyword Registry", 6817 RFC 5788, DOI 10.17487/RFC5788, March 2010, 6818 . 6820 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6821 Specifications: ABNF", STD 68, RFC 5234, January 2008, 6822 . 6824 [ANONYMOUS] 6825 Zeilenga, K., "Anonymous Simple Authentication and 6826 Security Layer (SASL) Mechanism", RFC 4505, June 2006, 6827 . 6829 [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration 6830 Procedures", BCP 19, RFC 2978, October 2000, 6831 . 6833 [SCRAM-SHA-256] 6834 Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple 6835 Authentication and Security Layer (SASL) Mechanisms", 6836 RFC 7677, DOI 10.17487/RFC7677, November 2015, 6837 . 6839 [DISPOSITION] 6840 Troost, R., Dorner, S., and K. Moore, Ed., "Communicating 6841 Presentation Information in Internet Messages: The 6842 Content-Disposition Header Field", RFC 2183, August 1997, 6843 . 6845 [PLAIN] Zeilenga, K., Ed., "The PLAIN Simple Authentication and 6846 Security Layer (SASL) Mechanism", RFC 4616, August 2006, 6847 . 6849 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6850 Requirement Levels", BCP 14, RFC 2119, 6851 DOI 10.17487/RFC2119, March 1997, 6852 . 6854 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 6855 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 6856 May 2017, . 6858 [LANGUAGE-TAGS] 6859 Alvestrand, H., "Content Language Headers", RFC 3282, May 6860 2002, . 6862 [LOCATION] 6863 Palme, J., Hopmann, A., and N. Shelness, "MIME 6864 Encapsulation of Aggregate Documents, such as HTML 6865 (MHTML)", RFC 2557, March 1999, 6866 . 6868 [MD5] Myers, J. and M. Rose, "The Content-MD5 Header Field", 6869 RFC 1864, October 1995, 6870 . 6872 [MIME-HDRS] 6873 Moore, K., "MIME (Multipurpose Internet Mail Extensions) 6874 Part Three: Message Header Extensions for Non-ASCII Text", 6875 RFC 2047, November 1996, 6876 . 6878 [MIME-IMB] 6879 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6880 Extensions (MIME) Part One: Format of Internet Message 6881 Bodies", RFC 2045, November 1996, 6882 . 6884 [MIME-IMT] 6885 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6886 Extensions (MIME) Part Two: Media Types", RFC 2046, 6887 November 1996, . 6889 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 6890 Word Extensions: Character Sets, Languages, and 6891 Continuations", RFC 2231, DOI 10.17487/RFC2231, November 6892 1997, . 6894 [RFC-5322] 6895 Resnick, P., Ed., "Internet Message Format", RFC 5322, 6896 October 2008, . 6898 [SASL] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 6899 Authentication and Security Layer (SASL)", RFC 4422, June 6900 2006, . 6902 [TLS-1.2] Dierks, T. and E. Rescorla, "The Transport Layer Security 6903 (TLS) Protocol Version 1.2", RFC 5246, August 2008, 6904 . 6906 [TLS-1.3] Rescorla, E., "The Transport Layer Security (TLS) Protocol 6907 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 6908 . 6910 [UTF-7] Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe 6911 Transformation Format of Unicode", RFC 2152, May 1997, 6912 . 6914 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 6915 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 6916 2003, . 6918 [MULTIAPPEND] 6919 Crispin, M., "Internet Message Access Protocol (IMAP) - 6920 MULTIAPPEND Extension", RFC 3502, March 2003, 6921 . 6923 [NET-UNICODE] 6924 Klensin, J. and M. Padlipsky, "Unicode Format for Network 6925 Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008, 6926 . 6928 [I18N-HDRS] 6929 Yang, A., Steele, S., and N. Freed, "Internationalized 6930 Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 6931 2012, . 6933 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 6934 Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, 6935 . 6937 [RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS) 6938 Server Identity Check Procedure for Email-Related 6939 Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016, 6940 . 6942 [RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition 6943 Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, 6944 February 2017, . 6946 [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: 6947 Use of Transport Layer Security (TLS) for Email Submission 6948 and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, 6949 . 6951 [IMAP-IMPLEMENTATION] 6952 Leiba, B., "IMAP4 Implementation Recommendations", 6953 RFC 2683, September 1999, 6954 . 6956 [IMAP-MULTIACCESS] 6957 Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", 6958 RFC 2180, July 1997, 6959 . 6961 13.2. Informative References (related protocols) 6963 [RFC3503] Melnikov, A., "Message Disposition Notification (MDN) 6964 profile for Internet Message Access Protocol (IMAP)", 6965 RFC 3503, DOI 10.17487/RFC3503, March 2003, 6966 . 6968 [RFC5256] Crispin, M. and K. Murchison, "Internet Message Access 6969 Protocol - SORT and THREAD Extensions", RFC 5256, 6970 DOI 10.17487/RFC5256, June 2008, 6971 . 6973 [RFC2193] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 6974 DOI 10.17487/RFC2193, September 1997, 6975 . 6977 [RFC3348] Gahrns, M. and R. Cheng, "The Internet Message Action 6978 Protocol (IMAP4) Child Mailbox Extension", RFC 3348, 6979 DOI 10.17487/RFC3348, July 2002, 6980 . 6982 [RFC5465] Gulbrandsen, A., King, C., and A. Melnikov, "The IMAP 6983 NOTIFY Extension", RFC 5465, DOI 10.17487/RFC5465, 6984 February 2009, . 6986 [RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals", 6987 RFC 7888, DOI 10.17487/RFC7888, May 2016, 6988 . 6990 [IMAP-DISC] 6991 Melnikov, A., Ed., "Synchronization Operations for 6992 Disconnected IMAP4 Clients", RFC 4549, June 2006, 6993 . 6995 [IMAP-I18N] 6996 Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 6997 Message Access Protocol Internationalization", RFC 5255, 6998 DOI 10.17487/RFC5255, June 2008, 6999 . 7001 [IMAP-MODEL] 7002 Crispin, M., "Distributed Electronic Mail Models in 7003 IMAP4", RFC 1733, December 1994, 7004 . 7006 [IMAP-UTF-8] 7007 Resnick, P., Ed., Newman, C., Ed., and S. Shen, Ed., "IMAP 7008 Support for UTF-8", RFC 6855, DOI 10.17487/RFC6855, March 7009 2013, . 7011 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 7012 October 2008, . 7014 [RFC3516] Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516, 7015 DOI 10.17487/RFC3516, April 2003, 7016 . 7018 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 7019 RFC 4314, December 2005, 7020 . 7022 [RFC2087] Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 7023 1997, . 7025 [IMAP-URL] 7026 Melnikov, A., Ed. and C. Newman, "IMAP URL Scheme", 7027 RFC 5092, DOI 10.17487/RFC5092, November 2007, 7028 . 7030 [IMAP-KEYWORDS-REG] 7031 IANA, "IMAP and JMAP Keywords", December 2009, 7032 . 7035 [IMAP-MAILBOX-NAME-ATTRS-REG] 7036 IANA, "IMAP Mailbox Name Attributes", June 2018, 7037 . 7040 [CHARSET-REG] 7041 IANA, "Character Set Registrations", May 2015, 7042 . 7045 13.3. Informative References (historical aspects of IMAP and related 7046 protocols) 7048 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 7049 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003, 7050 . 7052 [IMAP-COMPAT] 7053 Crispin, M., "IMAP4 Compatibility with IMAP2bis", 7054 RFC 2061, December 1996, 7055 . 7057 [IMAP-HISTORICAL] 7058 Crispin, M., "IMAP4 Compatibility with IMAP2 and 7059 IMAP2bis", RFC 1732, December 1994, 7060 . 7062 [IMAP-OBSOLETE] 7063 Crispin, M., "Internet Message Access Protocol - Obsolete 7064 Syntax", RFC 2062, December 1996, 7065 . 7067 [IMAP2] Crispin, M., "Interactive Mail Access Protocol: Version 7068 2", RFC 1176, August 1990, 7069 . 7071 [RFC-822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET 7072 TEXT MESSAGES", STD 11, RFC 822, August 1982, 7073 . 7075 [IMAP-TLS] 7076 Newman, C., "Using TLS with IMAP, POP3 and ACAP", 7077 RFC 2595, June 1999, 7078 . 7080 Appendix A. Backward compatibility with IMAP4rev1 7082 An implementation that wants to remain compatible with IMAP4rev1 can 7083 advertise both IMAP4rev1 and IMAP4rev2 in its CAPABILITY response/ 7084 response code. While some IMAP4rev1 responses were removed in 7085 IMAP4rev2, their presence will not break IMAP4rev2-only clients. 7087 If both IMAP4rev1 and IMAP4rev2 are advertised, an IMAP client that 7088 wants to use IMAP4rev2 MUST issue an "ENABLE IMAP4rev2" command. 7090 Servers advertising both IMAP4rev1 and IMAP4rev2 MUST NOT generate 7091 UTF-8 quoted strings unless the client has issued "ENABLE IMAP4rev2". 7093 Consider implementation of mechanisms described or referenced in 7094 [IMAP-UTF-8] to achieve this goal. 7096 Servers advertising both IMAP4rev1 and IMAP4rev2, and clients 7097 intending to be compatible with IMAP4rev1 servers MUST be compatible 7098 with the international mailbox naming convention described in the 7099 following subsection. 7101 A.1. Mailbox International Naming Convention for compatibility with 7102 IMAP4rev1 7104 Support for the Mailbox International Naming Convention described in 7105 this section is not required for IMAP4rev2-only clients and servers. 7106 It is only used for backward compatibility with IMAP4rev1 7107 implementations. 7109 By convention, international mailbox names in IMAP4rev1 are specified 7110 using a modified version of the UTF-7 encoding described in [UTF-7]. 7111 Modified UTF-7 may also be usable in servers that implement an 7112 earlier version of this protocol. 7114 In modified UTF-7, printable US-ASCII characters, except for "&", 7115 represent themselves; that is, characters with octet values 0x20-0x25 7116 and 0x27-0x7e. The character "&" (0x26) is represented by the two- 7117 octet sequence "&-". 7119 All other characters (octet values 0x00-0x1f and 0x7f-0xff) are 7120 represented in modified BASE64, with a further modification from 7121 [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be 7122 used to represent any printing US-ASCII character which can represent 7123 itself. Only characters inside the modified BASE64 alphabet are 7124 permitted in modified BASE64 text. 7126 "&" is used to shift to modified BASE64 and "-" to shift back to US- 7127 ASCII. There is no implicit shift from BASE64 to US-ASCII, and null 7128 shifts ("-&" while in BASE64; note that "&-" while in US-ASCII means 7129 "&") are not permitted. However, all names start in US-ASCII, and 7130 MUST end in US-ASCII; that is, a name that ends with a non-ASCII 7131 ISO-10646 character MUST end with a "-"). 7133 The purpose of these modifications is to correct the following 7134 problems with UTF-7: 7136 1. UTF-7 uses the "+" character for shifting; this conflicts with 7137 the common use of "+" in mailbox names, in particular USENET 7138 newsgroup names. 7140 2. UTF-7's encoding is BASE64 which uses the "/" character; this 7141 conflicts with the use of "/" as a popular hierarchy delimiter. 7143 3. UTF-7 prohibits the unencoded usage of "\"; this conflicts with 7144 the use of "\" as a popular hierarchy delimiter. 7146 4. UTF-7 prohibits the unencoded usage of "~"; this conflicts with 7147 the use of "~" in some servers as a home directory indicator. 7149 5. UTF-7 permits multiple alternate forms to represent the same 7150 string; in particular, printable US-ASCII characters can be 7151 represented in encoded form. 7153 Although modified UTF-7 is a convention, it establishes certain 7154 requirements on server handling of any mailbox name with an embedded 7155 "&" character. In particular, server implementations MUST preserve 7156 the exact form of the modified BASE64 portion of a modified UTF-7 7157 name and treat that text as case-sensitive, even if names are 7158 otherwise case-insensitive or case-folded. 7160 Server implementations SHOULD verify that any mailbox name with an 7161 embedded "&" character, used as an argument to CREATE, is: in the 7162 correctly modified UTF-7 syntax, has no superfluous shifts, and has 7163 no encoding in modified BASE64 of any printing US-ASCII character 7164 which can represent itself. However, client implementations MUST NOT 7165 depend upon the server doing this, and SHOULD NOT attempt to create a 7166 mailbox name with an embedded "&" character unless it complies with 7167 the modified UTF-7 syntax. 7169 Server implementations which export a mail store that does not follow 7170 the modified UTF-7 convention MUST convert to modified UTF-7 any 7171 mailbox name that contains either non-ASCII characters or the "&" 7172 character. 7174 For example, here is a mailbox name which mixes English, Chinese, 7175 and Japanese text: ~peter/mail/&U,BTFw-/&ZeVnLIqe- 7177 For example, the string "&Jjo!" is not a valid mailbox name 7178 because it does not contain a shift to US-ASCII before the "!". 7179 The correct form is "&Jjo-!". The string "&U,BTFw-&ZeVnLIqe-" is 7180 not permitted because it contains a superfluous shift. The 7181 correct form is "&U,BTF2XlZyyKng-". 7183 Appendix B. Backward compatibility with BINARY extension 7185 IMAP4rev2 is incorporates subset of functionality provided by the 7186 BINARY extension [RFC3516], in particular it includes additional 7187 FETCH items (BINARY, BINARY.PEEK and BINARY.SIZE), but not extensions 7188 to the APPEND command. IMAP4rev2 implementations that supports full 7189 RFC 3516 functionality need to also advertise the BINARY token in the 7190 CAPABILITY response. 7192 Appendix C. Backward compatibility with LIST-EXTENDED extension 7194 IMAP4rev2 is incorporates most of functionality provided by the LIST- 7195 EXTENDED extension [RFC5258]. In particular, multiple mailbox 7196 patterns syntax is not supported in IMAP4rev2, unless LIST-EXTENDED 7197 capability is also advertised in CAPABILITY response/response code. 7199 Appendix D. Changes from RFC 3501 / IMAP4rev1 7201 Below is the summary of changes since RFC 3501: 7203 1. Folded in IMAP NAMESPACE (RFC 2342), UNSELECT (RFC 3691), 7204 UIDPLUS (RFC 4315), ESEARCH (RFC 4731), SEARCHRES (RFC 5182), 7205 ENABLE (RFC 5161), IDLE (RFC 2177), SASL-IR (RFC 4959), LIST- 7206 EXTENDED (RFC 5258), LIST-STATUS (RFC 5819), MOVE (RFC 6851) and 7207 LITERAL- (RFC 7888) extensions. Also folded RFC 4466 (IMAP ABNF 7208 extensions), RFC 5530 (response codes), the FETCH side of the 7209 BINARY extension (RFC 3516) and the list of new mailbox 7210 attributes from SPECIAL-USE (RFC 6154). 7212 2. Added STATUS SIZE (RFC 8438) and STATUS DELETED. 7214 3. SEARCH command now requires to return ESEARCH response (SEARCH 7215 response is now deprecated). 7217 4. Clarified which SEARCH keys has to use substring match and which 7218 don't. 7220 5. Clarified that server should decode parameter value 7221 continuations as described in [RFC2231]. This requirement was 7222 hidden in RFC 2231 itself. 7224 6. Added CLOSED response code from RFC 7162. SELECT/EXAMINE when a 7225 mailbox is already selected now require for the CLOSED response 7226 code to be returned. 7228 7. SELECT/EXAMINE are now required to return untagged LIST 7229 response. 7231 8. UNSEEN response code on SELECT/EXAMINE is now deprecated. 7233 9. RECENT response on SELECT/EXAMINE, \Recent flag, RECENT STATUS, 7234 SEARCH NEW items are now deprecated. 7236 10. Clarified that the server doesn't need to send a new 7237 PERMANENTFLAGS response code when a new keyword was successfully 7238 added and the server advertised \* earlier for the same mailbox. 7240 11. For future extensibility extended ABNF for tagged-ext-simple to 7241 allow for bare number64. 7243 12. Added SHOULD level requirement on IMAP servers to support 7244 $MDNSent, $Forwarded, $Junk, $NonJunk and $Phishing keywords. 7246 13. Mailbox names and message headers now allow for UTF-8. Support 7247 for Modified UTF-7 in mailbox names is not required, unless 7248 compatibility with IMAP4rev1 is desired. 7250 14. Removed the CHECK command. Clients should use NOOP instead. 7252 15. RFC822, RFC822.HEADER and RFC822.TEXT FETCH data items were 7253 deprecated. Clients should use the corresponding BODY[] 7254 variants instead. 7256 16. LSUB command was deprecated. Clients should use LIST 7257 (SUBSCRIBED) instead. 7259 17. IDLE command can now return updates not related to the currently 7260 selected mailbox state. 7262 18. All unsolicited FETCH updates are required to include UID. 7264 19. Clarified that client implementations MUST ignore response codes 7265 that they do not recognize. (Change from a SHOULD to a MUST.) 7267 20. resp-text ABNF non terminal was updated to allow for empty text. 7269 21. After ENABLE IMAP4rev2 human readable response text can include 7270 non ASCII encoded in UTF-8. 7272 22. Updated to use modern TLS-related recommendations as per RFC 7273 8314, RFC 7817, RFC 7525. 7275 23. Replaced DIGEST-MD5 SASL mechanism with SCRAM-SHA-256. DIGEST- 7276 MD5 was deprecated. 7278 Appendix E. Other Recommended IMAP Extensions 7280 Support for the following extensions is recommended for all IMAP 7281 client and servers. Why they significantly reduce bandwidth and/or 7282 number of round trips used by IMAP in certain situations, the EXTRA 7283 WG decided that requiring them as a part of IMAP4rev2 would push the 7284 bar to implement too high for new implementations. Also note that 7285 absence of any IMAP extension from this list doesn't make it somehow 7286 deficient or not recommended for use with IMAP4rev2. 7288 1. QRESYNC and CONDSTORE extensions (RFC 7162). They make 7289 discovering changes to IMAP mailboxes more efficient, at the 7290 expense of storing a bit more state. 7292 2. OBJECTID extension (RFC 8474) helps with preserving IMAP client 7293 cache when messages moved/copied or mailboxes are renamed. 7295 Appendix F. Acknowledgement 7297 Earlier versions of this document were edited by Mark Crispin. 7298 Sadly, he is no longer available to help with this work. Editors of 7299 this revisions are hoping that Mark would have approved. 7301 Chris Newman has contributed text on I18N and use of UTF-8 in 7302 messages and mailbox names. 7304 Thank you to Tony Hansen for helping with the index generation. 7305 Thank you to Timo Sirainen, Bron Gondwana, Stephan Bosch and Arnt 7306 Gulbrandsen for extensive feedback. 7308 This document incorporate text from RFC 4315 (by Mark Crispin), RFC 7309 4466 (by Cyrus Daboo), RFC 4731 (by Dave Cridland), RFC 5161 (by Arnt 7310 Gulbrandsen), RFC 5465 (by Arnt Gulbrandsen and Curtis King), RFC 7311 5530 (by Arnt Gulbrandsen), RFC 5819 (by Timo Sirainen), RFC 6154 (by 7312 Jamie Nicolson), RFC 8438 (by Stephan Bosch) so work done by authors/ 7313 editors of these documents is appreciated. Note that editors of this 7314 document were redacted from the above list. 7316 The CHILDREN return option was originally proposed by Mike Gahrns and 7317 Raymond Cheng in [RFC3348]. Most of the information in 7318 Section 6.3.9.5 is taken directly from their original specification 7319 [RFC3348]. 7321 Index 7323 $ 7324 $Forwarded (predefined flag) 12 7325 $Junk (predefined flag) 12 7326 $MDNSent (predefined flag) 12 7327 $NotJunk (predefined flag) 12 7328 $Phishing (predefined flag) 13 7330 + 7331 +FLAGS 92 7332 +FLAGS.SILENT 92 7334 - 7335 -FLAGS 92 7336 -FLAGS.SILENT 92 7338 A 7339 ALERT (response code) 99 7340 ALL (fetch item) 88 7341 ALL (search key) 78 7342 ALL (search result option) 76 7343 ALREADYEXISTS (response code) 99 7344 ANSWERED (search key) 78 7345 APPEND (command) 68 7346 APPENDUID (response code) 100 7347 AUTHENTICATE (command) 29 7348 AUTHENTICATIONFAILED (response code) 100 7349 AUTHORIZATIONFAILED (response code) 101 7351 B 7352 BAD (response) 108 7353 BADCHARSET (response code) 101 7354 BCC (search key) 78 7355 BEFORE (search key) 78 7356 BINARY.PEEK[]<> (fetch item) 88 7357 BINARY.SIZE[] (fetch item) 89 7358 BINARY.SIZE[] (fetch result) 118 7359 BINARY[]<> (fetch result) 118 7360 BINARY[]<> (fetch item) 88 7361 BODY (fetch item) 89 7362 BODY (fetch result) 119 7363 BODY (search key) 78 7364 BODY.PEEK[
]<> (fetch item) 89 7365 BODYSTRUCTURE (fetch item) 90 7366 BODYSTRUCTURE (fetch result) 119 7367 BODY[
]<> (fetch result) 119 7368 BODY[
]<> (fetch item) 89 7369 BYE (response) 109 7370 Body Structure (message attribute) 14 7372 C 7373 CANNOT (response code) 101 7374 CAPABILITY (command) 25 7375 CAPABILITY (response code) 101 7376 CAPABILITY (response) 110 7377 CC (search key) 78 7378 CLIENTBUG (response code) 101 7379 CLOSE (command) 74 7380 CLOSED (response code) 102 7381 CONTACTADMIN (response code) 102 7382 COPY (command) 93 7383 COPYUID (response code) 102 7384 CORRUPTION (response code) 103 7385 COUNT (search result option) 76 7386 CREATE (command) 38 7388 D 7389 DELETE (command) 39 7390 DELETED (search key) 78 7391 DELETED (status item) 68 7392 DRAFT (search key) 78 7394 E 7395 ENABLE (command) 33 7396 ENVELOPE (fetch item) 90 7397 ENVELOPE (fetch result) 122 7398 ESEARCH (response) 115 7399 EXAMINE (command) 37 7400 EXPIRED (response code) 103 7401 EXPUNGE (command) 75 7402 EXPUNGE (response) 117 7403 EXPUNGEISSUED (response code) 103 7404 Envelope Structure (message attribute) 14 7406 F 7407 FAST (fetch item) 88 7408 FETCH (command) 87 7409 FETCH (response) 118 7410 FLAGGED (search key) 78 7411 FLAGS (fetch item) 90 7412 FLAGS (fetch result) 123 7413 FLAGS (response) 116 7414 FLAGS (store command data item) 92 7415 FLAGS.SILENT (store command data item) 92 7416 FROM (search key) 79 7417 FULL (fetch item) 88 7418 Flags (message attribute) 11 7420 H 7421 HASCHILDREN (response code) 103 7422 HEADER (part specifier) 90 7423 HEADER (search key) 79 7424 HEADER.FIELDS (part specifier) 90 7425 HEADER.FIELDS.NOT (part specifier) 90 7427 I 7428 IDLE (command) 71 7429 INTERNALDATE (fetch item) 90 7430 INTERNALDATE (fetch result) 123 7431 INUSE (response code) 104 7432 Internal Date (message attribute) 13 7434 K 7435 KEYWORD (search key) 79 7436 Keyword (type of flag) 12 7438 L 7439 LARGER (search key) 79 7440 LIMIT (response code) 104 7441 LIST (command) 44 7442 LIST (response) 111 7443 LOGOUT (command) 27 7445 M 7446 MAX (search result option) 76 7447 MAY (specification requirement term) 5 7448 MESSAGES (status item) 68 7449 MIME (part specifier) 91 7450 MIN (search result option) 76 7451 MOVE (command) 94 7452 MUST (specification requirement term) 5 7453 MUST NOT (specification requirement term) 5 7454 Message Sequence Number (message attribute) 11 7456 N 7457 NAMESPACE (command) 62 7458 NAMESPACE (response) 115 7459 NO (response) 108 7460 NONEXISTENT (response code) 104 7461 NOOP (command) 26 7462 NOPERM (response code) 104 7463 NOT (search key) 79 7464 NOT RECOMMENDED (specification requirement term) 5 7466 O 7467 OK (response) 107 7468 ON (search key) 79 7469 OPTIONAL (specification requirement term) 5 7470 OR (search key) 79 7471 OVERQUOTA (response code) 104 7473 P 7474 PARSE (response code) 105 7475 PERMANENTFLAGS (response code) 105 7476 PREAUTH (response) 108 7477 PRIVACYREQUIRED (response code) 105 7478 Permanent Flag (class of flag) 13 7479 Predefined keywords 12 7481 R 7482 READ-ONLY (response code) 106 7483 READ-WRITE (response code) 106 7484 RECOMMENDED (specification requirement term) 5 7485 RENAME (command) 41 7486 REQUIRED (specification requirement term) 5 7487 RFC822.SIZE (fetch item) 90 7488 RFC822.SIZE (fetch result) 123 7490 S 7491 SAVE (search result option) 76 7492 SEARCH (command) 75 7493 SEEN (search key) 79 7494 SELECT (command) 35 7495 SENTBEFORE (search key) 79 7496 SENTON (search key) 79 7497 SENTSINCE (search key) 79 7498 SERVERBUG (response code) 106 7499 SHOULD (specification requirement term) 5 7500 SHOULD NOT (specification requirement term) 5 7501 SINCE (search key) 79 7502 SIZE (status item) 68 7503 SMALLER (search key) 79 7504 STARTTLS (command) 28 7505 STATUS (command) 67 7506 STATUS (response) 115 7507 STORE (command) 92 7508 SUBJECT (search key) 80 7509 SUBSCRIBE (command) 43 7510 Session Flag (class of flag) 13 7511 System Flag (type of flag) 11 7513 T 7514 TEXT (part specifier) 90 7515 TEXT (search key) 80 7516 TO (search key) 80 7517 TRYCREATE (response code) 106 7519 U 7520 UID (command) 96 7521 UID (fetch item) 90 7522 UID (fetch result) 123 7523 UID (search key) 80 7524 UIDNEXT (response code) 106 7525 UIDNEXT (status item) 68 7526 UIDNOTSTICKY (response code) 106 7527 UIDVALIDITY (response code) 107 7528 UIDVALIDITY (status item) 68 7529 UNANSWERED (search key) 80 7530 UNAVAILABLE (response code) 107 7531 UNDELETED (search key) 80 7532 UNDRAFT (search key) 80 7533 UNFLAGGED (search key) 80 7534 UNKEYWORD (search key) 80 7535 UNKNOWN-CTE (response code) 107 7536 UNSEEN (search key) 80 7537 UNSEEN (status item) 68 7538 UNSELECT (command) 74 7539 UNSUBSCRIBE (command) 44 7540 Unique Identifier (UID) (message attribute) 9 7542 X 7543 X (command) 97 7545 [ 7546 [RFC-5322] Size (message attribute) 14 7548 \ 7549 \All (mailbox name attribute) 113 7550 \Answered (system flag) 12 7551 \Archive (mailbox name attribute) 113 7552 \Deleted (system flag) 12 7553 \Draft (system flag) 12 7554 \Drafts (mailbox name attribute) 113 7555 \Flagged (mailbox name attribute) 113 7556 \Flagged (system flag) 12 7557 \HasChildren (mailbox name attribute) 112 7558 \HasNoChildren (mailbox name attribute) 112 7559 \Junk (mailbox name attribute) 113 7560 \Marked (mailbox name attribute) 112 7561 \Noinferiors (mailbox name attribute) 111 7562 \NonExistent (mailbox name attribute) 111 7563 \Noselect (mailbox name attribute) 111 7564 \Recent (system flag) 12 7565 \Remote (mailbox name attribute) 112 7566 \Seen (system flag) 12 7567 \Sent (mailbox name attribute) 113 7568 \Subscribed (mailbox name attribute) 112 7569 \Trash (mailbox name attribute) 113 7570 \Unmarked (mailbox name attribute) 112 7572 Authors' Addresses 7574 Alexey Melnikov (editor) 7575 Isode Ltd 7576 14 Castle Mews 7577 Hampton, Middlesex TW12 2NP 7578 UK 7580 Email: Alexey.Melnikov@isode.com 7582 Barry Leiba (editor) 7583 Futurewei Technologies 7585 Phone: +1 646 827 0648 7586 Email: barryleiba@computer.org 7587 URI: http://internetmessagingtechnology.org/