idnits 2.17.1 draft-ietf-extra-imap4rev2-12.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 2 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 (February 12, 2020) is 1528 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 6771, but not defined == Missing Reference: 'IMAP-OBSOLETE' is mentioned on line 6766, but not defined == Missing Reference: 'IMAP-COMPAT' is mentioned on line 6756, but not defined == Missing Reference: 'IMAP-HISTORICAL' is mentioned on line 6761, but not defined == Missing Reference: 'RFC-822' is mentioned on line 6775, but not defined ** Obsolete undefined reference: RFC 822 (Obsoleted by RFC 2822) == Missing Reference: 'IMAP-DISC' is mentioned on line 6713, but not defined == Missing Reference: 'SMTP' is mentioned on line 6734, but not defined == Missing Reference: 'RFC7888' is mentioned on line 6709, but not defined -- Looks like a reference, but probably isn't: '1' on line 832 == Missing Reference: 'IMAP-URL' is mentioned on line 6748, but not defined == Missing Reference: 'UIDVALIDITY 3857529045' is mentioned on line 5572, but not defined == Missing Reference: 'UIDNEXT 4392' is mentioned on line 1661, but not defined == Missing Reference: 'RFC5258' is mentioned on line 6695, but not defined == Missing Reference: 'RFC2193' is mentioned on line 6700, but not defined == Missing Reference: 'RFC3348' is mentioned on line 6704, but not defined ** Obsolete undefined reference: RFC 3348 (Obsoleted by RFC 5258) == Missing Reference: 'RFC4314' is mentioned on line 6741, but not defined == Missing Reference: 'UIDNEXT 2' is mentioned on line 3120, but not defined == Missing Reference: 'UIDVALIDITY 1' is mentioned on line 3191, but not defined == Missing Reference: 'IMAP-I18N' is mentioned on line 6718, but not defined == Missing Reference: 'HEADER' is mentioned on line 5589, but not defined == Missing Reference: 'BADCHARSET UTF-8' is mentioned on line 3761, but not defined == Missing Reference: 'UID' is mentioned on line 4171, but not defined == Missing Reference: 'RFC2087' is mentioned on line 6745, but not defined ** Obsolete undefined reference: RFC 2087 (Obsoleted by RFC 9208) == Missing Reference: 'READ-WRITE' is mentioned on line 5573, but not defined == Missing Reference: 'RFC4422' is mentioned on line 5909, but not defined == Missing Reference: 'IMAP4' is mentioned on line 5995, but not defined == Missing Reference: 'Namespace-Response-Extensions' is mentioned on line 6061, but not defined == Missing Reference: 'IMAP-TLS' is mentioned on line 6779, but not defined == Missing Reference: 'RFC5256' is mentioned on line 6690, but not defined == Missing Reference: 'IMAP-MODEL' is mentioned on line 6724, but not defined == Missing Reference: 'IMAP-UTF-8' is mentioned on line 6797, but not defined == Missing Reference: 'RFC3516' is mentioned on line 6887, but not defined ** Obsolete normative reference: RFC 5246 (ref. 'TLS') (Obsoleted by RFC 8446) ** 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 (~~), 33 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 Huawei Technologies 6 Expires: August 15, 2020 February 12, 2020 8 INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev2 9 draft-ietf-extra-imap4rev2-12 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 August 15, 2020. 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 . . . . . . . . . . . 12 90 2.3.4. [RFC-5322] Size Message Attribute . . . . . . . . . . 13 91 2.3.5. Envelope Structure Message Attribute . . . . . . . . 13 92 2.3.6. Body Structure Message Attribute . . . . . . . . . . 13 93 2.4. Message Texts . . . . . . . . . . . . . . . . . . . . . . 13 94 3. State and Flow Diagram . . . . . . . . . . . . . . . . . . . 13 95 3.1. Not Authenticated State . . . . . . . . . . . . . . . . . 13 96 3.2. Authenticated State . . . . . . . . . . . . . . . . . . . 13 97 3.3. Selected State . . . . . . . . . . . . . . . . . . . . . 14 98 3.4. Logout State . . . . . . . . . . . . . . . . . . . . . . 14 99 4. Data Formats . . . . . . . . . . . . . . . . . . . . . . . . 16 100 4.1. Atom . . . . . . . . . . . . . . . . . . . . . . . . . . 16 101 4.1.1. Sequence set and UID set . . . . . . . . . . . . . . 16 102 4.2. Number . . . . . . . . . . . . . . . . . . . . . . . . . 16 103 4.3. String . . . . . . . . . . . . . . . . . . . . . . . . . 16 104 4.3.1. 8-bit and Binary Strings . . . . . . . . . . . . . . 17 105 4.4. Parenthesized List . . . . . . . . . . . . . . . . . . . 18 106 4.5. NIL . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 107 5. Operational Considerations . . . . . . . . . . . . . . . . . 19 108 5.1. Mailbox Naming . . . . . . . . . . . . . . . . . . . . . 19 109 5.1.1. Mailbox Hierarchy Naming . . . . . . . . . . . . . . 20 110 5.1.2. Namespaces . . . . . . . . . . . . . . . . . . . . . 20 111 5.2. Mailbox Size and Message Status Updates . . . . . . . . . 21 112 5.3. Response when no Command in Progress . . . . . . . . . . 22 113 5.4. Autologout Timer . . . . . . . . . . . . . . . . . . . . 22 114 5.5. Multiple Commands in Progress (Command Pipelining) . . . 22 115 6. Client Commands . . . . . . . . . . . . . . . . . . . . . . . 24 116 6.1. Client Commands - Any State . . . . . . . . . . . . . . . 24 117 6.1.1. CAPABILITY Command . . . . . . . . . . . . . . . . . 24 118 6.1.2. NOOP Command . . . . . . . . . . . . . . . . . . . . 25 119 6.1.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . 26 120 6.2. Client Commands - Not Authenticated State . . . . . . . . 26 121 6.2.1. STARTTLS Command . . . . . . . . . . . . . . . . . . 27 122 6.2.2. AUTHENTICATE Command . . . . . . . . . . . . . . . . 28 123 6.2.3. LOGIN Command . . . . . . . . . . . . . . . . . . . . 31 124 6.3. Client Commands - Authenticated State . . . . . . . . . . 32 125 6.3.1. ENABLE Command . . . . . . . . . . . . . . . . . . . 32 126 6.3.2. SELECT Command . . . . . . . . . . . . . . . . . . . 34 127 6.3.3. EXAMINE Command . . . . . . . . . . . . . . . . . . . 36 128 6.3.4. CREATE Command . . . . . . . . . . . . . . . . . . . 37 129 6.3.5. DELETE Command . . . . . . . . . . . . . . . . . . . 38 130 6.3.6. RENAME Command . . . . . . . . . . . . . . . . . . . 39 131 6.3.7. SUBSCRIBE Command . . . . . . . . . . . . . . . . . . 41 132 6.3.8. UNSUBSCRIBE Command . . . . . . . . . . . . . . . . . 42 133 6.3.9. LIST Command . . . . . . . . . . . . . . . . . . . . 42 134 6.3.10. NAMESPACE Command . . . . . . . . . . . . . . . . . . 60 135 6.3.11. STATUS Command . . . . . . . . . . . . . . . . . . . 65 136 6.3.12. APPEND Command . . . . . . . . . . . . . . . . . . . 66 137 6.3.13. IDLE Command . . . . . . . . . . . . . . . . . . . . 69 138 6.4. Client Commands - Selected State . . . . . . . . . . . . 71 139 6.4.1. CLOSE Command . . . . . . . . . . . . . . . . . . . . 71 140 6.4.2. UNSELECT Command . . . . . . . . . . . . . . . . . . 72 141 6.4.3. EXPUNGE Command . . . . . . . . . . . . . . . . . . . 72 142 6.4.4. SEARCH Command . . . . . . . . . . . . . . . . . . . 73 143 6.4.5. FETCH Command . . . . . . . . . . . . . . . . . . . . 85 144 6.4.6. STORE Command . . . . . . . . . . . . . . . . . . . . 89 145 6.4.7. COPY Command . . . . . . . . . . . . . . . . . . . . 90 146 6.4.8. MOVE Command . . . . . . . . . . . . . . . . . . . . 91 147 6.4.9. UID Command . . . . . . . . . . . . . . . . . . . . . 93 148 6.5. Client Commands - Experimental/Expansion . . . . . . . . 95 149 6.5.1. X Command . . . . . . . . . . . . . . . . . . . 95 150 7. Server Responses . . . . . . . . . . . . . . . . . . . . . . 96 151 7.1. Server Responses - Status Responses . . . . . . . . . . . 97 152 7.1.1. OK Response . . . . . . . . . . . . . . . . . . . . . 105 153 7.1.2. NO Response . . . . . . . . . . . . . . . . . . . . . 105 154 7.1.3. BAD Response . . . . . . . . . . . . . . . . . . . . 106 155 7.1.4. PREAUTH Response . . . . . . . . . . . . . . . . . . 106 156 7.1.5. BYE Response . . . . . . . . . . . . . . . . . . . . 106 157 7.2. Server Responses - Server and Mailbox Status . . . . . . 107 158 7.2.1. The ENABLED Response . . . . . . . . . . . . . . . . 107 159 7.2.2. CAPABILITY Response . . . . . . . . . . . . . . . . . 107 160 7.2.3. LIST Response . . . . . . . . . . . . . . . . . . . . 108 161 7.2.4. NAMESPACE Response . . . . . . . . . . . . . . . . . 112 162 7.2.5. STATUS Response . . . . . . . . . . . . . . . . . . . 112 163 7.2.6. ESEARCH Response . . . . . . . . . . . . . . . . . . 113 164 7.2.7. FLAGS Response . . . . . . . . . . . . . . . . . . . 113 165 7.3. Server Responses - Mailbox Size . . . . . . . . . . . . . 114 166 7.3.1. EXISTS Response . . . . . . . . . . . . . . . . . . . 114 167 7.4. Server Responses - Message Status . . . . . . . . . . . . 114 168 7.4.1. EXPUNGE Response . . . . . . . . . . . . . . . . . . 114 169 7.4.2. FETCH Response . . . . . . . . . . . . . . . . . . . 115 170 7.5. Server Responses - Command Continuation Request . . . . . 121 171 8. Sample IMAP4rev2 connection . . . . . . . . . . . . . . . . . 121 172 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 122 173 10. Author's Note . . . . . . . . . . . . . . . . . . . . . . . . 139 174 11. Security Considerations . . . . . . . . . . . . . . . . . . . 139 175 11.1. STARTTLS Security Considerations . . . . . . . . . . . . 140 176 11.2. COPYUID and APPENDUID response codes . . . . . . . . . . 140 177 11.3. LIST command and Other Users' namespace . . . . . . . . 140 178 11.4. Other Security Considerations . . . . . . . . . . . . . 140 179 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 141 180 12.1. Updates to IMAP4 Capabilities registry . . . . . . . . . 142 181 12.2. GSSAPI/SASL service name . . . . . . . . . . . . . . . . 142 182 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 142 183 13.1. Normative References . . . . . . . . . . . . . . . . . . 142 184 13.2. Informative References (related protocols) . . . . . . . 145 185 13.3. Informative References (historical aspects of IMAP and 186 related protocols) . . . . . . . . . . . . . . . . . . . 146 187 Appendix A. Backward compatibility with IMAP4rev1 . . . . . . . 147 188 A.1. Mailbox International Naming Convention for compatibility 189 with IMAP4rev1 . . . . . . . . . . . . . . . . . . . . . 148 190 Appendix B. Backward compatibility with BINARY extension . . . . 149 191 Appendix C. Changes from RFC 3501 / IMAP4rev1 . . . . . . . . . 149 192 Appendix D. Acknowledgement . . . . . . . . . . . . . . . . . . 152 193 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 194 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 157 196 1. How to Read This Document 198 1.1. Organization of This Document 200 This document is written from the point of view of the implementor of 201 an IMAP4rev2 client or server. Beyond the protocol overview in 202 section 2, it is not optimized for someone trying to understand the 203 operation of the protocol. The material in sections 3 through 5 204 provides the general context and definitions with which IMAP4rev2 205 operates. 207 Sections 6, 7, and 9 describe the IMAP commands, responses, and 208 syntax, respectively. The relationships among these are such that it 209 is almost impossible to understand any of them separately. In 210 particular, do not attempt to deduce command syntax from the command 211 section alone; instead refer to the Formal Syntax section. 213 1.2. Conventions Used in This Document 215 "Conventions" are basic principles or procedures. Document 216 conventions are noted in this section. 218 In examples, "C:" and "S:" indicate lines sent by the client and 219 server respectively. 221 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 222 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 223 "OPTIONAL" in this document are to be interpreted as described in BCP 224 14 [RFC2119] [RFC8174] when, and only when, they appear in all 225 capitals, as shown here. 227 The word "can" (not "may") is used to refer to a possible 228 circumstance or situation, as opposed to an optional facility of the 229 protocol. 231 "User" is used to refer to a human user, whereas "client" refers to 232 the software being run by the user. 234 "Connection" refers to the entire sequence of client/server 235 interaction from the initial establishment of the network connection 236 until its termination. 238 "Session" refers to the sequence of client/server interaction from 239 the time that a mailbox is selected (SELECT or EXAMINE command) until 240 the time that selection ends (SELECT or EXAMINE of another mailbox, 241 CLOSE command, UNSELECT command, or connection termination). 243 Characters are 8-bit UTF-8 (of which 7-bit US-ASCII is a subset) 244 unless otherwise specified. Other character sets are indicated using 245 a "CHARSET", as described in [MIME-IMT] and defined in [CHARSET]. 246 CHARSETs have important additional semantics in addition to defining 247 character set; refer to these documents for more detail. 249 There are several protocol conventions in IMAP. These refer to 250 aspects of the specification which are not strictly part of the IMAP 251 protocol, but reflect generally-accepted practice. Implementations 252 need to be aware of these conventions, and avoid conflicts whether or 253 not they implement the convention. For example, "&" may not be used 254 as a hierarchy delimiter since it conflicts with the Mailbox 255 International Naming Convention, and other uses of "&" in mailbox 256 names are impacted as well. 258 1.3. Special Notes to Implementors 260 Implementors of the IMAP protocol are strongly encouraged to read the 261 IMAP implementation recommendations document [IMAP-IMPLEMENTATION] in 262 conjunction with this document, to help understand the intricacies of 263 this protocol and how best to build an interoperable product. 265 IMAP4rev2 is designed to be upwards compatible from the [IMAP2] and 266 unpublished IMAP2bis protocols. IMAP4rev2 is largely compatible with 267 the IMAP4rev1 protocol described in RFC 3501 and the IMAP4 protocol 268 described in RFC 1730; the exception being in certain facilities 269 added in RFC 1730 that proved problematic and were subsequently 270 removed. In the course of the evolution of IMAP4rev2, some aspects 271 in the earlier protocols have become obsolete. Obsolete commands, 272 responses, and data formats which an IMAP4rev2 implementation can 273 encounter when used with an earlier implementation are described in 274 Appendix C and [IMAP-OBSOLETE]. 276 Other compatibility issues with IMAP2bis, the most common variant of 277 the earlier protocol, are discussed in [IMAP-COMPAT]. A full 278 discussion of compatibility issues with rare (and presumed extinct) 279 variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is 280 primarily of historical interest. 282 IMAP was originally developed for the older [RFC-822] standard, and 283 as a consequence several fetch items in IMAP incorporate "RFC822" in 284 their name. In all cases, "RFC822" should be interpreted as a 285 reference to the updated [RFC-5322] standard. 287 2. Protocol Overview 289 2.1. Link Level 291 The IMAP4rev2 protocol assumes a reliable data stream such as that 292 provided by TCP. When TCP is used, an IMAP4rev2 server listens on 293 port 143 or port 993 (IMAP-over-TLS). 295 2.2. Commands and Responses 297 An IMAP4rev2 connection consists of the establishment of a client/ 298 server network connection, an initial greeting from the server, and 299 client/server interactions. These client/server interactions consist 300 of a client command, server data, and a server completion result 301 response. 303 All interactions transmitted by client and server are in the form of 304 lines, that is, strings that end with a CRLF. The protocol receiver 305 of an IMAP4rev2 client or server is either reading a line, or is 306 reading a sequence of octets with a known count followed by a line. 308 2.2.1. Client Protocol Sender and Server Protocol Receiver 310 The client command begins an operation. Each client command is 311 prefixed with an identifier (typically a short alphanumeric string, 312 e.g., A0001, A0002, etc.) called a "tag". A different tag is 313 generated by the client for each command. 315 Clients MUST follow the syntax outlined in this specification 316 strictly. It is a syntax error to send a command with missing or 317 extraneous spaces or arguments. 319 There are two cases in which a line from the client does not 320 represent a complete command. In one case, a command argument is 321 quoted with an octet count (see the description of literal in String 322 under Data Formats); in the other case, the command arguments require 323 server feedback (see the AUTHENTICATE command). In either case, the 324 server sends a command continuation request response if it is ready 325 for the octets (if appropriate) and the remainder of the command. 326 This response is prefixed with the token "+". 328 Note: If instead, the server detected an error in the command, it 329 sends a BAD completion response with a tag matching the command 330 (as described below) to reject the command and prevent the client 331 from sending any more of the command. 333 It is also possible for the server to send a completion response 334 for some other command (if multiple commands are in progress), or 335 untagged data. In either case, the command continuation request 336 is still pending; the client takes the appropriate action for the 337 response, and reads another response from the server. In all 338 cases, the client MUST send a complete command (including 339 receiving all command continuation request responses and command 340 continuations for the command) before initiating a new command. 342 The protocol receiver of an IMAP4rev2 server reads a command line 343 from the client, parses the command and its arguments, and transmits 344 server data and a server command completion result response. 346 2.2.2. Server Protocol Sender and Client Protocol Receiver 348 Data transmitted by the server to the client and status responses 349 that do not indicate command completion are prefixed with the token 350 "*", and are called untagged responses. 352 Server data MAY be sent as a result of a client command, or MAY be 353 sent unilaterally by the server. There is no syntactic difference 354 between server data that resulted from a specific command and server 355 data that were sent unilaterally. 357 The server completion result response indicates the success or 358 failure of the operation. It is tagged with the same tag as the 359 client command which began the operation. Thus, if more than one 360 command is in progress, the tag in a server completion response 361 identifies the command to which the response applies. There are 362 three possible server completion responses: OK (indicating success), 363 NO (indicating failure), or BAD (indicating a protocol error such as 364 unrecognized command or command syntax error). 366 Servers SHOULD enforce the syntax outlined in this specification 367 strictly. Any client command with a protocol syntax error, including 368 (but not limited to) missing or extraneous spaces or arguments, 369 SHOULD be rejected, and the client given a BAD server completion 370 response. 372 The protocol receiver of an IMAP4rev2 client reads a response line 373 from the server. It then takes action on the response based upon the 374 first token of the response, which can be a tag, a "*", or a "+". 376 A client MUST be prepared to accept any server response at all times. 377 This includes server data that was not requested. Server data SHOULD 378 be recorded, so that the client can reference its recorded copy 379 rather than sending a command to the server to request the data. In 380 the case of certain server data, the data MUST be recorded. 382 This topic is discussed in greater detail in the Server Responses 383 section. 385 2.3. Message Attributes 387 In addition to message text, each message has several attributes 388 associated with it. These attributes can be retrieved individually 389 or in conjunction with other attributes or message texts. 391 2.3.1. Message Numbers 393 Messages in IMAP4rev2 are accessed by one of two numbers; the unique 394 identifier or the message sequence number. 396 2.3.1.1. Unique Identifier (UID) Message Attribute 398 An unsigned 32-bit value assigned to each message, which when used 399 with the unique identifier validity value (see below) forms a 64-bit 400 value that MUST NOT refer to any other message in the mailbox or any 401 subsequent mailbox with the same name forever. Unique identifiers 402 are assigned in a strictly ascending fashion in the mailbox; as each 403 message is added to the mailbox it is assigned a higher UID than the 404 message(s) which were added previously. Unlike message sequence 405 numbers, unique identifiers are not necessarily contiguous. 407 The unique identifier of a message MUST NOT change during the 408 session, and SHOULD NOT change between sessions. Any change of 409 unique identifiers between sessions MUST be detectable using the 410 UIDVALIDITY mechanism discussed below. Persistent unique identifiers 411 are required for a client to resynchronize its state from a previous 412 session with the server (e.g., disconnected or offline access 413 clients); this is discussed further in [IMAP-DISC]. 415 Associated with every mailbox are two 32-bit unsigned values which 416 aid in unique identifier handling: the next unique identifier value 417 (UIDNEXT) and the unique identifier validity value (UIDVALIDITY). 419 The next unique identifier value is the predicted value that will be 420 assigned to a new message in the mailbox. Unless the unique 421 identifier validity also changes (see below), the next unique 422 identifier value MUST have the following two characteristics. First, 423 the next unique identifier value MUST NOT change unless new messages 424 are added to the mailbox; and second, the next unique identifier 425 value MUST change whenever new messages are added to the mailbox, 426 even if those new messages are subsequently expunged. 428 Note: The next unique identifier value is intended to provide a 429 means for a client to determine whether any messages have been 430 delivered to the mailbox since the previous time it checked this 431 value. It is not intended to provide any guarantee that any 432 message will have this unique identifier. A client can only 433 assume, at the time that it obtains the next unique identifier 434 value, that messages arriving after that time will have a UID 435 greater than or equal to that value. 437 The unique identifier validity value is sent in a UIDVALIDITY 438 response code in an OK untagged response at mailbox selection time. 439 If unique identifiers from an earlier session fail to persist in this 440 session, the unique identifier validity value MUST be greater than 441 the one used in the earlier session. 443 Note: Ideally, unique identifiers SHOULD persist at all times. 444 Although this specification recognizes that failure to persist can 445 be unavoidable in certain server environments, it STRONGLY 446 ENCOURAGES message store implementation techniques that avoid this 447 problem. For example: 449 1. Unique identifiers MUST be strictly ascending in the mailbox 450 at all times. If the physical message store is re-ordered by 451 a non-IMAP agent, this requires that the unique identifiers in 452 the mailbox be regenerated, since the former unique 453 identifiers are no longer strictly ascending as a result of 454 the re-ordering. 456 2. If the message store has no mechanism to store unique 457 identifiers, it must regenerate unique identifiers at each 458 session, and each session must have a unique UIDVALIDITY 459 value. 461 3. If the mailbox is deleted and a new mailbox with the same name 462 is created at a later date, the server must either keep track 463 of unique identifiers from the previous instance of the 464 mailbox, or it must assign a new UIDVALIDITY value to the new 465 instance of the mailbox. A good UIDVALIDITY value to use in 466 this case is a 32-bit representation of the creation date/time 467 of the mailbox. It is alright to use a constant such as 1, 468 but only if it guaranteed that unique identifiers will never 469 be reused, even in the case of a mailbox being deleted (or 470 renamed) and a new mailbox by the same name created at some 471 future time. 473 4. The combination of mailbox name, UIDVALIDITY, and UID must 474 refer to a single immutable message on that server forever. 475 In particular, the internal date, [RFC-5322] size, envelope, 476 body structure, and message texts (all BODY[...] fetch data 477 items) must never change. This does not include message 478 numbers, nor does it include attributes that can be set by a 479 STORE command (e.g., FLAGS). 481 2.3.1.2. Message Sequence Number Message Attribute 483 A relative position from 1 to the number of messages in the mailbox. 484 This position MUST be ordered by ascending unique identifier. As 485 each new message is added, it is assigned a message sequence number 486 that is 1 higher than the number of messages in the mailbox before 487 that new message was added. 489 Message sequence numbers can be reassigned during the session. For 490 example, when a message is permanently removed (expunged) from the 491 mailbox, the message sequence number for all subsequent messages is 492 decremented. The number of messages in the mailbox is also 493 decremented. Similarly, a new message can be assigned a message 494 sequence number that was once held by some other message prior to an 495 expunge. 497 In addition to accessing messages by relative position in the 498 mailbox, message sequence numbers can be used in mathematical 499 calculations. For example, if an untagged "11 EXISTS" is received, 500 and previously an untagged "8 EXISTS" was received, three new 501 messages have arrived with message sequence numbers of 9, 10, and 11. 502 Another example, if message 287 in a 523 message mailbox has UID 503 12345, there are exactly 286 messages which have lesser UIDs and 236 504 messages which have greater UIDs. 506 2.3.2. Flags Message Attribute 508 A list of zero or more named tokens associated with the message. A 509 flag is set by its addition to this list, and is cleared by its 510 removal. There are two types of flags in IMAP4rev2. A flag of 511 either type can be permanent or session-only. 513 A system flag is a flag name that is pre-defined in this 514 specification and begin with "\". Certain system flags (\Deleted and 515 \Seen) have special semantics described elsewhere in this document. 516 The currently-defined system flags are: 518 \Seen Message has been read 520 \Answered Message has been answered 522 \Flagged Message is "flagged" for urgent/special attention 524 \Deleted Message is "deleted" for removal by later EXPUNGE 525 \Draft Message has not completed composition (marked as a draft). 527 \Recent This flag was in used in IMAP4rev1 and is now deprecated. 529 A keyword is defined by the server implementation. Keywords do not 530 begin with "\". Servers MAY permit the client to define new keywords 531 in the mailbox (see the description of the PERMANENTFLAGS response 532 code for more information). Some keywords that start with "$" are 533 also defined in this specification. 535 This document defines several keywords that were not originally 536 defined in RFC 3501, but which were found to be useful by client 537 implementations. These keywords SHOULD be supported (i.e. allowed in 538 APPEND, COPY, MOVE and SEARCH commands) by server implementations: 540 $Forwarded Message has been forwarded to another email address, 541 embedded within or attached to a new message. An email client 542 sets this keyword when it successfully forwards the message to 543 another email address. Typical usage of this keyword is to show a 544 different (or additional) icon for a message that has been 545 forwarded. Once set, the flag SHOULD NOT be cleared. 547 $MDNSent Message Disposition Notification [RFC8098] was generated 548 and sent for this message. 550 A flag can be permanent or session-only on a per-flag basis. 551 Permanent flags are those which the client can add or remove from the 552 message flags permanently; that is, concurrent and subsequent 553 sessions will see any change in permanent flags. Changes to session 554 flags are valid only in that session. 556 2.3.3. Internal Date Message Attribute 558 The internal date and time of the message on the server. This is not 559 the date and time in the [RFC-5322] header, but rather a date and 560 time which reflects when the message was received. In the case of 561 messages delivered via [SMTP], this SHOULD be the date and time of 562 final delivery of the message as defined by [SMTP]. In the case of 563 messages delivered by the IMAP4rev2 COPY or MOVE command, this SHOULD 564 be the internal date and time of the source message. In the case of 565 messages delivered by the IMAP4rev2 APPEND command, this SHOULD be 566 the date and time as specified in the APPEND command description. 567 All other cases are implementation defined. 569 2.3.4. [RFC-5322] Size Message Attribute 571 The number of octets in the message, as expressed in [RFC-5322] 572 format. 574 2.3.5. Envelope Structure Message Attribute 576 A parsed representation of the [RFC-5322] header of the message. 577 Note that the IMAP Envelope structure is not the same as an [SMTP] 578 envelope. 580 2.3.6. Body Structure Message Attribute 582 A parsed representation of the [MIME-IMB] body structure information 583 of the message. 585 2.4. Message Texts 587 In addition to being able to fetch the full [RFC-5322] text of a 588 message, IMAP4rev2 permits the fetching of portions of the full 589 message text. Specifically, it is possible to fetch the [RFC-5322] 590 message header, [RFC-5322] message body, a [MIME-IMB] body part, or a 591 [MIME-IMB] header. 593 3. State and Flow Diagram 595 Once the connection between client and server is established, an 596 IMAP4rev2 connection is in one of four states. The initial state is 597 identified in the server greeting. Most commands are only valid in 598 certain states. It is a protocol error for the client to attempt a 599 command while the connection is in an inappropriate state, and the 600 server will respond with a BAD or NO (depending upon server 601 implementation) command completion result. 603 3.1. Not Authenticated State 605 In the not authenticated state, the client MUST supply authentication 606 credentials before most commands will be permitted. This state is 607 entered when a connection starts unless the connection has been pre- 608 authenticated. 610 3.2. Authenticated State 612 In the authenticated state, the client is authenticated and MUST 613 select a mailbox to access before commands that affect messages will 614 be permitted. This state is entered when a pre-authenticated 615 connection starts, when acceptable authentication credentials have 616 been provided, after an error in selecting a mailbox, or after a 617 successful CLOSE command. 619 3.3. Selected State 621 In a selected state, a mailbox has been selected to access. This 622 state is entered when a mailbox has been successfully selected. 624 3.4. Logout State 626 In the logout state, the connection is being terminated. This state 627 can be entered as a result of a client request (via the LOGOUT 628 command) or by unilateral action on the part of either the client or 629 server. 631 If the client requests the logout state, the server MUST send an 632 untagged BYE response and a tagged OK response to the LOGOUT command 633 before the server closes the connection; and the client MUST read the 634 tagged OK response to the LOGOUT command before the client closes the 635 connection. 637 A server SHOULD NOT unilaterally close the connection without sending 638 an untagged BYE response that contains the reason for having done so. 639 A client SHOULD NOT unilaterally close the connection, and instead 640 SHOULD issue a LOGOUT command. If the server detects that the client 641 has unilaterally closed the connection, the server MAY omit the 642 untagged BYE response and simply close its connection. 644 +----------------------+ 645 |connection established| 646 +----------------------+ 647 || 648 \/ 649 +--------------------------------------+ 650 | server greeting | 651 +--------------------------------------+ 652 || (1) || (2) || (3) 653 \/ || || 654 +-----------------+ || || 655 |Not Authenticated| || || 656 +-----------------+ || || 657 || (7) || (4) || || 658 || \/ \/ || 659 || +----------------+ || 660 || | Authenticated |<=++ || 661 || +----------------+ || || 662 || || (7) || (5) || (6) || 663 || || \/ || || 664 || || +--------+ || || 665 || || |Selected|==++ || 666 || || +--------+ || 667 || || || (7) || 668 \/ \/ \/ \/ 669 +--------------------------------------+ 670 | Logout | 671 +--------------------------------------+ 672 || 673 \/ 674 +-------------------------------+ 675 |both sides close the connection| 676 +-------------------------------+ 678 (1) connection without pre-authentication (OK greeting) 679 (2) pre-authenticated connection (PREAUTH greeting) 680 (3) rejected connection (BYE greeting) 681 (4) successful LOGIN or AUTHENTICATE command 682 (5) successful SELECT or EXAMINE command 683 (6) CLOSE command, unsolicited CLOSED response code or 684 failed SELECT or EXAMINE command 685 (7) LOGOUT command, server shutdown, or connection closed 687 4. Data Formats 689 IMAP4rev2 uses textual commands and responses. Data in IMAP4rev2 can 690 be in one of several forms: atom, number, string, parenthesized list, 691 or NIL. Note that a particular data item may take more than one 692 form; for example, a data item defined as using "astring" syntax may 693 be either an atom or a string. 695 4.1. Atom 697 An atom consists of one or more non-special characters. 699 4.1.1. Sequence set and UID set 701 A set of messages can be referenced by a sequence set containing 702 either message sequence numbers or unique identifiers. See Section 9 703 for details. Sequence sets can contain ranges (e.g. "5:50"), an 704 enumeration of specific message/UID numbers, a special symbol "*", or 705 a combination of the above. 707 A "UID set" is similar to the sequence set of unique identifiers; 708 however, the "*" value for a sequence number is not permitted. 710 4.2. Number 712 A number consists of one or more digit characters, and represents a 713 numeric value. 715 4.3. String 717 A string is in one of three forms: synchonizing literal, non- 718 synchronizing literal or quoted string. The synchronizing literal 719 form is the general form of string. The non-synchronizing literal 720 form is also the general form, but has length limitation. The quoted 721 string form is an alternative that avoids the overhead of processing 722 a literal at the cost of limitations of characters which may be used. 724 When the distinction between synchronizing and non-synchronizing 725 literals is not important, this document just uses the term 726 "literal". 728 A synchronizing literal is a sequence of zero or more octets 729 (including CR and LF), prefix-quoted with an octet count in the form 730 of an open brace ("{"), the number of octets, close brace ("}"), and 731 CRLF. In the case of synchronizing literals transmitted from server 732 to client, the CRLF is immediately followed by the octet data. In 733 the case of synchronizing literals transmitted from client to server, 734 the client MUST wait to receive a command continuation request 735 (described later in this document) before sending the octet data (and 736 the remainder of the command). 738 The non-synchronizing literal is an alternate form of synchronizing 739 literal, and it may appear in communication from client to server 740 instead of the synchonizing form of literal. The non-synchronizing 741 literal form MUST NOT be sent from server to client. The non- 742 synchronizing literal is distinguished from the synchronizing literal 743 by having a plus ("+") between the octet count and the closing brace 744 ("}"). The server does not generate a command continuation request 745 in response to a non-synchronizing literal, and clients are not 746 required to wait before sending the octets of a non- synchronizing 747 literal. Non-synchronizing literals MUST NOT be larger than 4096 748 octets. Any literal larger than 4096 bytes MUST be sent as a 749 synchronizing literal. (Non-synchronizing literals defined in this 750 document are the same as non-synchronizing literals defined by the 751 LITERAL- extension from [RFC7888]. See that document for details on 752 how to handle invalid non-synchronizing literals longer than 4096 753 octets and for interaction with other IMAP extensions.) 755 A quoted string is a sequence of zero or more Unicode characters, 756 excluding CR and LF, encoded in UTF-8, with double quote (<">) 757 characters at each end. 759 The empty string is represented as "" (a quoted string with zero 760 characters between double quotes), as {0} followed by CRLF (a 761 synchronizing literal with an octet count of 0) or as {0+} followed 762 by CRLF (a non-synchronizing literal with an octet count of 0). 764 Note: Even if the octet count is 0, a client transmitting a 765 synchronizing literal MUST wait to receive a command continuation 766 request. 768 4.3.1. 8-bit and Binary Strings 770 8-bit textual and binary mail is supported through the use of a 771 [MIME-IMB] content transfer encoding. IMAP4rev2 implementations MAY 772 transmit 8-bit or multi-octet characters in literals, but SHOULD do 773 so only when the [CHARSET] is identified. 775 IMAP4rev2 is compatible with [I18N-HDRS]. As a result, the 776 identified charset for header-field values with 8-bit content is 777 UTF-8 [UTF-8]. IMAP4rev2 implementations MUST accept and MAY 778 transmit [UTF-8] text in quoted-strings as long as the string does 779 not contain NUL, CR, or LF. This differs from IMAP4rev1 780 implementations. 782 Although a BINARY content transfer encoding is defined, unencoded 783 binary strings are not permitted, unless returned in a in 784 response to BINARY.PEEK[]<> or 785 BINARY[]<> FETCH data item. A "binary 786 string" is any string with NUL characters. A string with an 787 excessive amount of CTL characters MAY also be considered to be 788 binary. Unless returned in response to BINARY.PEEK[...]/BINARY[...] 789 FETCH, client and server implementations MUST encode binary data into 790 a textual form, such as BASE64, before transmitting the data. 792 4.4. Parenthesized List 794 Data structures are represented as a "parenthesized list"; a sequence 795 of data items, delimited by space, and bounded at each end by 796 parentheses. A parenthesized list can contain other parenthesized 797 lists, using multiple levels of parentheses to indicate nesting. 799 The empty list is represented as () -- a parenthesized list with no 800 members. 802 4.5. NIL 804 The special form "NIL" represents the non-existence of a particular 805 data item that is represented as a string or parenthesized list, as 806 distinct from the empty string "" or the empty parenthesized list (). 808 Note: NIL is never used for any data item which takes the form of 809 an atom. For example, a mailbox name of "NIL" is a mailbox named 810 NIL as opposed to a non-existent mailbox name. This is because 811 mailbox uses "astring" syntax which is an atom or a string. 812 Conversely, an addr-name of NIL is a non-existent personal name, 813 because addr-name uses "nstring" syntax which is NIL or a string, 814 but never an atom. 816 Examples: 818 The following LIST response: 820 * LIST () "/" NIL 822 is equivalent to: 823 * LIST () "/" "NIL" 825 as LIST response ABNF is using astring for mailbox name. 827 However, the following response 829 * FETCH 1 (BODY[1] NIL) 831 is not equivalent to: 832 * FETCH 1 (BODY[1] "NIL") 833 The former means absence of the body part, while the latter 834 means that it contains literal sequence of characters "NIL". 836 5. Operational Considerations 838 The following rules are listed here to ensure that all IMAP4rev2 839 implementations interoperate properly. 841 5.1. Mailbox Naming 843 In IMAP4rev2, Mailbox names are encoded in Net-Unicode [NET-UNICODE] 844 (this differs from IMAP4rev1). Client implementations MAY attempt to 845 create Net-Unicode mailbox names, and MUST interpret any 8-bit 846 mailbox names returned by LIST as [NET-UNICODE]. Server 847 implementations MUST prohibit the creation of 8-bit mailbox names 848 that do not comply with Net-Unicode (however, servers MAY accept a 849 de-normalized UTF-8 mailbox name and convert it to Net-Unicode prior 850 to mailbox creation). 852 The case-insensitive mailbox name INBOX is a special name reserved to 853 mean "the primary mailbox for this user on this server". (Note that 854 this special name may not exist on some servers for some users, for 855 example if the user has no access to personal namespace.) The 856 interpretation of all other names is implementation-dependent. 858 In particular, this specification takes no position on case 859 sensitivity in non-INBOX mailbox names. Some server implementations 860 are fully case-sensitive in ASCII range; others preserve case of a 861 newly-created name but otherwise are case-insensitive; and yet others 862 coerce names to a particular case. Client implementations MUST 863 interact with any of these. 865 There are certain client considerations when creating a new mailbox 866 name: 868 1. Any character which is one of the atom-specials (see the Formal 869 Syntax) will require that the mailbox name be represented as a 870 quoted string or literal. 872 2. CTL and other non-graphic characters are difficult to represent 873 in a user interface and are best avoided. Servers MAY refuse to 874 create mailbox names containing Unicode CTL characters. 876 3. Although the list-wildcard characters ("%" and "*") are valid in 877 a mailbox name, it is difficult to use such mailbox names with 878 the LIST command due to the conflict with wildcard 879 interpretation. 881 4. Usually, a character (determined by the server implementation) is 882 reserved to delimit levels of hierarchy. 884 5. Two characters, "#" and "&", have meanings by convention, and 885 should be avoided except when used in that convention. 887 5.1.1. Mailbox Hierarchy Naming 889 If it is desired to export hierarchical mailbox names, mailbox names 890 MUST be left-to-right hierarchical using a single character to 891 separate levels of hierarchy. The same hierarchy separator character 892 is used for all levels of hierarchy within a single name. 894 5.1.2. Namespaces 896 Personal Namespace: A namespace that the server considers within the 897 personal scope of the authenticated user on a particular connection. 898 Typically, only the authenticated user has access to mailboxes in 899 their Personal Namespace. It is the part of the namespace that 900 belongs to the user that is allocated for mailboxes. If an INBOX 901 exists for a user, it MUST appear within the user's personal 902 namespace. In the typical case, there SHOULD be only one Personal 903 Namespace on a server. 905 Other Users' Namespace: A namespace that consists of mailboxes from 906 the Personal Namespaces of other users. To access mailboxes in the 907 Other Users' Namespace, the currently authenticated user MUST be 908 explicitly granted access rights. For example, it is common for a 909 manager to grant to their secretary access rights to their mailbox. 910 In the typical case, there SHOULD be only one Other Users' Namespace 911 on a server. 913 Shared Namespace: A namespace that consists of mailboxes that are 914 intended to be shared amongst users and do not exist within a user's 915 Personal Namespace. 917 The namespaces a server uses MAY differ on a per-user basis. 919 5.1.2.1. Historic Mailbox Namespace Naming Convention 921 By convention, the first hierarchical element of any mailbox name 922 which begins with "#" identifies the "namespace" of the remainder of 923 the name. This makes it possible to disambiguate between different 924 types of mailbox stores, each of which have their own namespaces. 926 For example, implementations which offer access to USENET 927 newsgroups MAY use the "#news" namespace to partition the USENET 928 newsgroup namespace from that of other mailboxes. Thus, the 929 comp.mail.misc newsgroup would have a mailbox name of 930 "#news.comp.mail.misc", and the name "comp.mail.misc" can refer to 931 a different object (e.g., a user's private mailbox). 933 Namespaces that include the "#" character are not IMAP URL [IMAP-URL] 934 friendly requiring the "#" character to be represented as %23 when 935 within URLs. As such, server implementers MAY instead consider using 936 namespace prefixes that do not contain the "#" character. 938 5.1.2.2. Common namespace models 940 Previous version of this protocol does not define a default server 941 namespace. Two common namespace models have evolved: 943 The "Personal Mailbox" model, in which the default namespace that is 944 presented consists of only the user's personal mailboxes. To access 945 shared mailboxes, the user must use an escape mechanism to reach 946 another namespace. 948 The "Complete Hierarchy" model, in which the default namespace that 949 is presented includes the user's personal mailboxes along with any 950 other mailboxes they have access to. 952 5.2. Mailbox Size and Message Status Updates 954 At any time, a server can send data that the client did not request. 955 Sometimes, such behavior is REQUIRED. For example, agents other than 956 the server MAY add messages to the mailbox (e.g., new message 957 delivery), change the flags of the messages in the mailbox (e.g., 958 simultaneous access to the same mailbox by multiple agents), or even 959 remove messages from the mailbox. A server MUST send mailbox size 960 updates automatically if a mailbox size change is observed during the 961 processing of a command. A server SHOULD send message flag updates 962 automatically, without requiring the client to request such updates 963 explicitly. 965 Special rules exist for server notification of a client about the 966 removal of messages to prevent synchronization errors; see the 967 description of the EXPUNGE response for more detail. In particular, 968 it is NOT permitted to send an EXISTS response that would reduce the 969 number of messages in the mailbox; only the EXPUNGE response can do 970 this. 972 Regardless of what implementation decisions a client makes on 973 remembering data from the server, a client implementation MUST record 974 mailbox size updates. It MUST NOT assume that any command after the 975 initial mailbox selection will return the size of the mailbox. 977 5.3. Response when no Command in Progress 979 Server implementations are permitted to send an untagged response 980 (except for EXPUNGE) while there is no command in progress. Server 981 implementations that send such responses MUST deal with flow control 982 considerations. Specifically, they MUST either (1) verify that the 983 size of the data does not exceed the underlying transport's available 984 window size, or (2) use non-blocking writes. 986 5.4. Autologout Timer 988 If a server has an inactivity autologout timer that applies to 989 sessions after authentication, the duration of that timer MUST be at 990 least 30 minutes. The receipt of ANY command from the client during 991 that interval SHOULD suffice to reset the autologout timer. 993 5.5. Multiple Commands in Progress (Command Pipelining) 995 The client MAY send another command without waiting for the 996 completion result response of a command, subject to ambiguity rules 997 (see below) and flow control constraints on the underlying data 998 stream. Similarly, a server MAY begin processing another command 999 before processing the current command to completion, subject to 1000 ambiguity rules. However, any command continuation request responses 1001 and command continuations MUST be negotiated before any subsequent 1002 command is initiated. 1004 The exception is if an ambiguity would result because of a command 1005 that would affect the results of other commands. If the server 1006 detects a possible ambiguity, it MUST execute commands to completion 1007 in the order given by the client. 1009 The most obvious example of ambiguity is when a command would affect 1010 the results of another command, e.g., a FETCH of a message's flags 1011 and a STORE of that same message's flags. 1013 A non-obvious ambiguity occurs with commands that permit an untagged 1014 EXPUNGE response (commands other than FETCH, STORE, and SEARCH), 1015 since an untagged EXPUNGE response can invalidate sequence numbers in 1016 a subsequent command. This is not a problem for FETCH, STORE, or 1017 SEARCH commands because servers are prohibited from sending EXPUNGE 1018 responses while any of those commands are in progress. Therefore, if 1019 the client sends any command other than FETCH, STORE, or SEARCH, it 1020 MUST wait for the completion result response before sending a command 1021 with message sequence numbers. 1023 Note: EXPUNGE responses are permitted while UID FETCH, UID STORE, 1024 and UID SEARCH are in progress. If the client sends a UID 1025 command, it MUST wait for a completion result response before 1026 sending a command which uses message sequence numbers (this may 1027 include UID SEARCH). Any message sequence numbers in an argument 1028 to UID SEARCH are associated with messages prior to the effect of 1029 any untagged EXPUNGE returned by the UID SEARCH. 1031 For example, the following non-waiting command sequences are invalid: 1033 FETCH + NOOP + STORE 1035 STORE + COPY + FETCH 1037 COPY + COPY 1039 The following are examples of valid non-waiting command sequences: 1041 FETCH + STORE + SEARCH + NOOP 1043 STORE + COPY + EXPUNGE 1045 UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting 1046 command sequence, depending upon whether or not the second UID 1047 SEARCH contains message sequence numbers. 1049 Use of SEARCH result variable (see Section 6.4.4.1) creates direct 1050 dependency between two commands. See Section 6.4.4.2 for more 1051 considerations about pipelining such dependent commands. 1053 6. Client Commands 1055 IMAP4rev2 commands are described in this section. Commands are 1056 organized by the state in which the command is permitted. Commands 1057 which are permitted in multiple states are listed in the minimum 1058 permitted state (for example, commands valid in authenticated and 1059 selected state are listed in the authenticated state commands). 1061 Command arguments, identified by "Arguments:" in the command 1062 descriptions below, are described by function, not by syntax. The 1063 precise syntax of command arguments is described in the Formal Syntax 1064 (Section 9). 1066 Some commands cause specific server responses to be returned; these 1067 are identified by "Responses:" in the command descriptions below. 1068 See the response descriptions in the Responses section for 1069 information on these responses, and the Formal Syntax section for the 1070 precise syntax of these responses. It is possible for server data to 1071 be transmitted as a result of any command. Thus, commands that do 1072 not specifically require server data specify "no specific responses 1073 for this command" instead of "none". 1075 The "Result:" in the command description refers to the possible 1076 tagged status responses to a command, and any special interpretation 1077 of these status responses. 1079 The state of a connection is only changed by successful commands 1080 which are documented as changing state. A rejected command (BAD 1081 response) never changes the state of the connection or of the 1082 selected mailbox. A failed command (NO response) generally does not 1083 change the state of the connection or of the selected mailbox; the 1084 exception being the SELECT and EXAMINE commands. 1086 6.1. Client Commands - Any State 1088 The following commands are valid in any state: CAPABILITY, NOOP, and 1089 LOGOUT. 1091 6.1.1. CAPABILITY Command 1093 Arguments: none 1095 Responses: REQUIRED untagged response: CAPABILITY 1097 Result: OK - capability completed 1098 BAD - command unknown or arguments invalid 1100 The CAPABILITY command requests a listing of capabilities that the 1101 server supports. The server MUST send a single untagged CAPABILITY 1102 response with "IMAP4rev2" as one of the listed capabilities before 1103 the (tagged) OK response. 1105 A capability name which begins with "AUTH=" indicates that the server 1106 supports that particular authentication mechanism. All such names 1107 are, by definition, part of this specification. For example, the 1108 authorization capability for an experimental "blurdybloop" 1109 authenticator would be "AUTH=XBLURDYBLOOP" and not 1110 "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP". 1112 Other capability names refer to extensions, revisions, or amendments 1113 to this specification. See the documentation of the CAPABILITY 1114 response for additional information. No capabilities, beyond the 1115 base IMAP4rev2 set defined in this specification, are enabled without 1116 explicit client action to invoke the capability. 1118 Client and server implementations MUST implement the STARTTLS, 1119 LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) capabilities. 1120 See the Security Considerations section for important information. 1122 See the section entitled "Client Commands - Experimental/Expansion" 1123 for information about the form of site or implementation-specific 1124 capabilities. 1126 Example: C: abcd CAPABILITY 1127 S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI 1128 LOGINDISABLED 1129 S: abcd OK CAPABILITY completed 1130 C: efgh STARTTLS 1131 S: efgh OK STARTLS completed 1132 1133 C: ijkl CAPABILITY 1134 S: * CAPABILITY IMAP4rev2 AUTH=GSSAPI AUTH=PLAIN 1135 S: ijkl OK CAPABILITY completed 1137 6.1.2. NOOP Command 1139 Arguments: none 1141 Responses: no specific responses for this command (but see below) 1143 Result: OK - noop completed 1144 BAD - command unknown or arguments invalid 1146 The NOOP command always succeeds. It does nothing. 1148 Since any command can return a status update as untagged data, the 1149 NOOP command can be used as a periodic poll for new messages or 1150 message status updates during a period of inactivity (the IDLE 1151 command Section 6.3.13 should be used instead of NOOP if real-time 1152 updates to mailbox state are desirable). The NOOP command can also 1153 be used to reset any inactivity autologout timer on the server. 1155 Example: C: a002 NOOP 1156 S: a002 OK NOOP completed 1157 . . . 1158 C: a047 NOOP 1159 S: * 22 EXPUNGE 1160 S: * 23 EXISTS 1161 S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted)) 1162 S: a047 OK NOOP completed 1164 6.1.3. LOGOUT Command 1166 Arguments: none 1168 Responses: REQUIRED untagged response: BYE 1170 Result: OK - logout completed 1171 BAD - command unknown or arguments invalid 1173 The LOGOUT command informs the server that the client is done with 1174 the connection. The server MUST send a BYE untagged response before 1175 the (tagged) OK response, and then close the network connection. 1177 Example: C: A023 LOGOUT 1178 S: * BYE IMAP4rev2 Server logging out 1179 S: A023 OK LOGOUT completed 1180 (Server and client then close the connection) 1182 6.2. Client Commands - Not Authenticated State 1184 In the not authenticated state, the AUTHENTICATE or LOGIN command 1185 establishes authentication and enters the authenticated state. The 1186 AUTHENTICATE command provides a general mechanism for a variety of 1187 authentication techniques, privacy protection, and integrity 1188 checking; whereas the LOGIN command uses a traditional user name and 1189 plaintext password pair and has no means of establishing privacy 1190 protection or integrity checking. 1192 The STARTTLS command is an alternate form of establishing session 1193 privacy protection and integrity checking, but does not by itself 1194 establish authentication or enter the authenticated state. 1196 Server implementations MAY allow access to certain mailboxes without 1197 establishing authentication. This can be done by means of the 1198 ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older 1199 convention is a LOGIN command using the userid "anonymous"; in this 1200 case, a password is required although the server may choose to accept 1201 any password. The restrictions placed on anonymous users are 1202 implementation-dependent. 1204 Once authenticated (including as anonymous), it is not possible to 1205 re-enter not authenticated state. 1207 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1208 the following commands are valid in the not authenticated state: 1209 STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations 1210 section for important information about these commands. 1212 6.2.1. STARTTLS Command 1214 Arguments: none 1216 Responses: no specific response for this command 1218 Result: OK - starttls completed, begin TLS negotiation 1219 BAD - command unknown or arguments invalid 1221 A [TLS] negotiation begins immediately after the CRLF at the end of 1222 the tagged OK response from the server. Once a client issues a 1223 STARTTLS command, it MUST NOT issue further commands until a server 1224 response is seen and the [TLS] negotiation is complete. 1226 The server remains in the non-authenticated state, even if client 1227 credentials are supplied during the [TLS] negotiation. This does not 1228 preclude an authentication mechanism such as EXTERNAL (defined in 1229 [SASL]) from using client identity determined by the [TLS] 1230 negotiation. 1232 Once [TLS] has been started, the client MUST discard cached 1233 information about server capabilities and SHOULD re-issue the 1234 CAPABILITY command. This is necessary to protect against man-in- 1235 the-middle attacks which alter the capabilities list prior to 1236 STARTTLS. The server MAY advertise different capabilities, and in 1237 particular SHOULD NOT advertise the STARTTLS capability, after a 1238 successful STARTTLS command. 1240 Example: C: a001 CAPABILITY 1241 S: * CAPABILITY IMAP4rev2 STARTTLS LOGINDISABLED 1242 S: a001 OK CAPABILITY completed 1243 C: a002 STARTTLS 1244 S: a002 OK Begin TLS negotiation now 1245 1246 C: a003 CAPABILITY 1247 S: * CAPABILITY IMAP4rev2 AUTH=PLAIN 1248 S: a003 OK CAPABILITY completed 1249 C: a004 LOGIN joe password 1250 S: a004 OK LOGIN completed 1252 6.2.2. AUTHENTICATE Command 1254 Arguments: SASL authentication mechanism name 1255 OPTIONAL initial response 1257 Responses: continuation data can be requested 1259 Result: OK - authenticate completed, now in authenticated state 1260 NO - authenticate failure: unsupported authentication 1261 mechanism, credentials rejected 1262 BAD - command unknown or arguments invalid, 1263 authentication exchange cancelled 1265 The AUTHENTICATE command indicates a [SASL] authentication mechanism 1266 to the server. If the server supports the requested authentication 1267 mechanism, it performs an authentication protocol exchange to 1268 authenticate and identify the client. It MAY also negotiate an 1269 OPTIONAL security layer for subsequent protocol interactions. If the 1270 requested authentication mechanism is not supported, the server 1271 SHOULD reject the AUTHENTICATE command by sending a tagged NO 1272 response. 1274 The AUTHENTICATE command supports the optional "initial response" 1275 feature defined in Section 5.1 of [SASL]. The client doesn't need to 1276 use it. If a SASL mechanism supports "initial response", but it is 1277 not specified by the client, the server handles this as specified in 1278 Section 3 of [SASL]. 1280 The service name specified by this protocol's profile of [SASL] is 1281 "imap". 1283 The authentication protocol exchange consists of a series of server 1284 challenges and client responses that are specific to the 1285 authentication mechanism. A server challenge consists of a command 1286 continuation request response with the "+" token followed by a BASE64 1287 encoded (see Section 4 of [RFC4648]) string. The client response 1288 consists of a single line consisting of a BASE64 encoded string. If 1289 the client wishes to cancel an authentication exchange, it issues a 1290 line consisting of a single "*". If the server receives such a 1291 response, or if it receives an invalid BASE64 string (e.g. 1292 characters outside the BASE64 alphabet, or non-terminal "="), it MUST 1293 reject the AUTHENTICATE command by sending a tagged BAD response. 1295 As with any other client response, this initial response MUST be 1296 encoded as BASE64. It also MUST be transmitted outside of a quoted 1297 string or literal. To send a zero-length initial response, the 1298 client MUST send a single pad character ("="). This indicates that 1299 the response is present, but is a zero-length string. 1301 When decoding the BASE64 data in the initial response, decoding 1302 errors MUST be treated as in any normal SASL client response, i.e. 1303 with a tagged BAD response. In particular, the server should check 1304 for any characters not explicitly allowed by the BASE64 alphabet, as 1305 well as any sequence of BASE64 characters that contains the pad 1306 character ('=') anywhere other than the end of the string (e.g., 1307 "=AAA" and "AAA=BBB" are not allowed). 1309 If the client uses an initial response with a SASL mechanism that 1310 does not support an initial response, the server MUST reject the 1311 command with a tagged BAD response. 1313 If a security layer is negotiated through the [SASL] authentication 1314 exchange, it takes effect immediately following the CRLF that 1315 concludes the authentication exchange for the client, and the CRLF of 1316 the tagged OK response for the server. 1318 While client and server implementations MUST implement the 1319 AUTHENTICATE command itself, it is not required to implement any 1320 authentication mechanisms other than the PLAIN mechanism described in 1321 [PLAIN]. Also, an authentication mechanism is not required to 1322 support any security layers. 1324 Note: a server implementation MUST implement a configuration in 1325 which it does NOT permit any plaintext password mechanisms, unless 1326 either the STARTTLS command has been negotiated or some other 1327 mechanism that protects the session from password snooping has 1328 been provided. Server sites SHOULD NOT use any configuration 1329 which permits a plaintext password mechanism without such a 1330 protection mechanism against password snooping. Client and server 1331 implementations SHOULD implement additional [SASL] mechanisms that 1332 do not use plaintext passwords, such the GSSAPI mechanism 1333 described in [SASL] and/or the SCRAM-SHA-256/SCRAM-SHA-256-PLUS 1334 [SCRAM-SHA-256] mechanisms. 1336 Servers and clients can support multiple authentication mechanisms. 1337 The server SHOULD list its supported authentication mechanisms in the 1338 response to the CAPABILITY command so that the client knows which 1339 authentication mechanisms to use. 1341 A server MAY include a CAPABILITY response code in the tagged OK 1342 response of a successful AUTHENTICATE command in order to send 1343 capabilities automatically. It is unnecessary for a client to send a 1344 separate CAPABILITY command if it recognizes these automatic 1345 capabilities. This should only be done if a security layer was not 1346 negotiated by the AUTHENTICATE command, because the tagged OK 1347 response as part of an AUTHENTICATE command is not protected by 1348 encryption/integrity checking. [SASL] requires the client to re- 1349 issue a CAPABILITY command in this case. The server MAY advertise 1350 different capabilities after a successful AUTHENTICATE command. 1352 If an AUTHENTICATE command fails with a NO response, the client MAY 1353 try another authentication mechanism by issuing another AUTHENTICATE 1354 command. It MAY also attempt to authenticate by using the LOGIN 1355 command (see Section 6.2.3 for more detail). In other words, the 1356 client MAY request authentication types in decreasing order of 1357 preference, with the LOGIN command as a last resort. 1359 The authorization identity passed from the client to the server 1360 during the authentication exchange is interpreted by the server as 1361 the user name whose privileges the client is requesting. 1363 Example: S: * OK IMAP4rev2 Server 1364 C: A001 AUTHENTICATE GSSAPI 1365 S: + 1366 C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw 1367 MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0 1368 b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW 1369 Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA 1370 cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX 1371 AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y 1372 C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb 1373 I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi 1374 vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL 1375 pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n 1376 FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE 1377 NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx 1378 O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB 1379 vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg== 1380 S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC 1381 AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0 1382 uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg== 1383 C: 1384 S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe 1385 ceP2CWY0SR0fAQAgAAQEBAQ= 1386 C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP 1387 wkhbfa2QteAQAgAG1yYwE= 1388 S: A001 OK GSSAPI authentication successful 1390 Note: The line breaks within server challenges and client responses 1391 are for editorial clarity and are not in real authenticators. 1393 6.2.3. LOGIN Command 1395 Arguments: user name 1396 password 1398 Responses: no specific responses for this command 1400 Result: OK - login completed, now in authenticated state 1401 NO - login failure: user name or password rejected 1402 BAD - command unknown or arguments invalid 1404 The LOGIN command identifies the client to the server and carries the 1405 plaintext password authenticating this user. 1407 A server MAY include a CAPABILITY response code in the tagged OK 1408 response to a successful LOGIN command in order to send capabilities 1409 automatically. It is unnecessary for a client to send a separate 1410 CAPABILITY command if it recognizes these automatic capabilities. 1412 Example: C: a001 LOGIN SMITH SESAME 1413 S: a001 OK LOGIN completed 1415 Note: Use of the LOGIN command over an insecure network (such as the 1416 Internet) is a security risk, because anyone monitoring network 1417 traffic can obtain plaintext passwords. The LOGIN command SHOULD NOT 1418 be used except as a last resort, and it is recommended that client 1419 implementations have a means to disable any automatic use of the 1420 LOGIN command. 1422 Unless either the client is accessing IMAP service on IMAPS port 1423 [RFC8314], the STARTTLS command has been negotiated or some other 1424 mechanism that protects the session from password snooping has been 1425 provided, a server implementation MUST implement a configuration in 1426 which it advertises the LOGINDISABLED capability and does NOT permit 1427 the LOGIN command. Server sites SHOULD NOT use any configuration 1428 which permits the LOGIN command without such a protection mechanism 1429 against password snooping. A client implementation MUST NOT send a 1430 LOGIN command if the LOGINDISABLED capability is advertised. 1432 6.3. Client Commands - Authenticated State 1434 In the authenticated state, commands that manipulate mailboxes as 1435 atomic entities are permitted. Of these commands, the SELECT and 1436 EXAMINE commands will select a mailbox for access and enter the 1437 selected state. 1439 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1440 the following commands are valid in the authenticated state: ENABLE, 1441 SELECT, EXAMINE, NAMESPACE, CREATE, DELETE, RENAME, SUBSCRIBE, 1442 UNSUBSCRIBE, LIST, STATUS, APPEND and IDLE. 1444 6.3.1. ENABLE Command 1446 Arguments: capability names 1448 Responses: no specific responses for this command 1450 Result: OK - Relevant capabilities enabled 1451 BAD - No arguments, or syntax error in an argument 1453 Several IMAP extensions allow the server to return unsolicited 1454 responses specific to these extensions in certain circumstances. 1455 However, servers cannot send those unsolicited responses (with the 1456 exception of response codes (see Section 7.1) included in tagged or 1457 untagged OK/NO/BAD responses, which can always be sent) until they 1458 know that the clients support such extensions and thus won't choke on 1459 the extension response data. 1461 The ENABLE command provides an explicit indication from the client 1462 that it supports particular extensions. It is designed such that the 1463 client can send a simple constant string with the extensions it 1464 supports, and the server will enable the shared subset that both 1465 support. 1467 The ENABLE command takes a list of capability names, and requests the 1468 server to enable the named extensions. Once enabled using ENABLE, 1469 each extension remains active until the IMAP connection is closed. 1470 For each argument, the server does the following: 1472 o If the argument is not an extension known to the server, the 1473 server MUST ignore the argument. 1475 o If the argument is an extension known to the server, and it is not 1476 specifically permitted to be enabled using ENABLE, the server MUST 1477 ignore the argument. (Note that knowing about an extension 1478 doesn't necessarily imply supporting that extension.) 1480 o If the argument is an extension that is supported by the server 1481 and that needs to be enabled, the server MUST enable the extension 1482 for the duration of the connection. Note that once an extension 1483 is enabled, there is no way to disable it. 1485 If the ENABLE command is successful, the server MUST send an untagged 1486 ENABLED response Section 7.2.1. 1488 Clients SHOULD only include extensions that need to be enabled by the 1489 server. For example, a client can enable IMAP4rev2 specific 1490 behaviour when both IMAP4rev1 and IMAP4rev2 are advertised in the 1491 CAPABILITY response. Future RFCs may add to this list. 1493 The ENABLE command is only valid in the authenticated state, before 1494 any mailbox is selected. Clients MUST NOT issue ENABLE once they 1495 SELECT/EXAMINE a mailbox; however, server implementations don't have 1496 to check that no mailbox is selected or was previously selected 1497 during the duration of a connection. 1499 The ENABLE command can be issued multiple times in a session. It is 1500 additive; i.e., "ENABLE a b", followed by "ENABLE c" is the same as a 1501 single command "ENABLE a b c". When multiple ENABLE commands are 1502 issued, each corresponding ENABLED response SHOULD only contain 1503 extensions enabled by the corresponding ENABLE command, i.e. for the 1504 above example, the ENABLED response to "ENABLE c" should not contain 1505 "a" or "b". 1507 There are no limitations on pipelining ENABLE. For example, it is 1508 possible to send ENABLE and then immediately SELECT, or a LOGIN 1509 immediately followed by ENABLE. 1511 The server MUST NOT change the CAPABILITY list as a result of 1512 executing ENABLE; i.e., a CAPABILITY command issued right after an 1513 ENABLE command MUST list the same capabilities as a CAPABILITY 1514 command issued before the ENABLE command. This is demonstrated in 1515 the following example: 1517 C: t1 CAPABILITY 1518 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1519 S: t1 OK foo 1520 C: t2 ENABLE CONDSTORE X-GOOD-IDEA 1521 S: * ENABLED X-GOOD-IDEA 1522 S: t2 OK foo 1523 C: t3 CAPABILITY 1524 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1525 S: t3 OK foo again 1527 In the following example, the client enables CONDSTORE: 1529 C: a1 ENABLE CONDSTORE 1530 S: * ENABLED CONDSTORE 1531 S: a1 OK Conditional Store enabled 1533 6.3.1.1. Note to Designers of Extensions That May Use the ENABLE 1534 Command 1536 Designers of IMAP extensions are discouraged from creating extensions 1537 that require ENABLE unless there is no good alternative design. 1538 Specifically, extensions that cause potentially incompatible behavior 1539 changes to deployed server responses (and thus benefit from ENABLE) 1540 have a higher complexity cost than extensions that do not. 1542 6.3.2. SELECT Command 1544 Arguments: mailbox name 1546 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1547 REQUIRED OK untagged responses: PERMANENTFLAGS, 1548 UIDNEXT, UIDVALIDITY 1550 Result: OK - select completed, now in selected state 1551 NO - select failure, now in authenticated state: no 1552 such mailbox, can't access mailbox 1553 BAD - command unknown or arguments invalid 1555 The SELECT command selects a mailbox so that messages in the mailbox 1556 can be accessed. Before returning an OK to the client, the server 1557 MUST send the following untagged data to the client. Note that 1558 earlier versions of this protocol only required the FLAGS and EXISTS 1559 untagged data; consequently, client implementations SHOULD implement 1560 default behavior for missing data as discussed with the individual 1561 item. 1563 FLAGS Defined flags in the mailbox. See the description of the 1564 FLAGS response for more detail. 1566 EXISTS The number of messages in the mailbox. See the 1567 description of the EXISTS response for more detail. 1569 OK [PERMANENTFLAGS ()] A list of message flags that 1570 the client can change permanently. If this is missing, the client 1571 should assume that all flags can be changed permanently. 1573 OK [UIDNEXT ] The next unique identifier value. Refer to 1574 Section 2.3.1.1 for more information. If this is missing, the 1575 client can not make any assumptions about the next unique 1576 identifier value. 1578 OK [UIDVALIDITY ] The unique identifier validity value. Refer to 1579 Section 2.3.1.1 for more information. If this is missing, the 1580 server does not support unique identifiers. 1582 Only one mailbox can be selected at a time in a connection; 1583 simultaneous access to multiple mailboxes requires multiple 1584 connections. The SELECT command automatically deselects any 1585 currently selected mailbox before attempting the new selection. 1586 Consequently, if a mailbox is selected and a SELECT command that 1587 fails is attempted, no mailbox is selected. When deselecting a 1588 selected mailbox, the server MUST return an untagged OK response with 1589 the "[CLOSED]" response code when the currently selected mailbox is 1590 closed (see Paragraph 10). 1592 If the client is permitted to modify the mailbox, the server SHOULD 1593 prefix the text of the tagged OK response with the "[READ-WRITE]" 1594 response code. 1596 If the client is not permitted to modify the mailbox but is permitted 1597 read access, the mailbox is selected as read-only, and the server 1598 MUST prefix the text of the tagged OK response to SELECT with the 1599 "[READ-ONLY]" response code. Read-only access through SELECT differs 1600 from the EXAMINE command in that certain read-only mailboxes MAY 1601 permit the change of permanent state on a per-user (as opposed to 1602 global) basis. Netnews messages marked in a server-based .newsrc 1603 file are an example of such per-user permanent state that can be 1604 modified with read-only mailboxes. 1606 Example: C: A142 SELECT INBOX 1607 S: * 172 EXISTS 1608 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1609 S: * OK [UIDNEXT 4392] Predicted next UID 1610 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1611 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1612 S: A142 OK [READ-WRITE] SELECT completed 1614 Example: C: A142 SELECT INBOX 1615 S: * 172 EXISTS 1616 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1617 S: * OK [UIDNEXT 4392] Predicted next UID 1618 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1619 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1620 S: A142 OK [READ-WRITE] SELECT completed 1621 [...some time later...] 1622 C: A143 SELECT Drafts 1623 S: * OK [CLOSED] Previous mailbox is now closed 1624 S: * 5 EXISTS 1625 S: * OK [UIDVALIDITY 9877410381] UIDs valid 1626 S: * OK [UIDNEXT 102] Predicted next UID 1627 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1628 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Answered 1629 \Flagged \Draft \*)] System flags and keywords allowed 1630 S: A143 OK [READ-WRITE] SELECT completed 1632 Note that IMAP4rev1 compliant servers can also send the untagged 1633 RECENT response which was deprecated in IMAP4rev2. E.g. "* 0 1634 RECENT". Pure IMAP4rev2 clients are advised to ignore the untagged 1635 RECENT response. 1637 6.3.3. EXAMINE Command 1639 Arguments: mailbox name 1641 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1642 REQUIRED OK untagged responses: PERMANENTFLAGS, 1643 UIDNEXT, UIDVALIDITY 1645 Result: OK - examine completed, now in selected state 1646 NO - examine failure, now in authenticated state: no 1647 such mailbox, can't access mailbox BAD - command unknown 1648 or arguments invalid 1650 The EXAMINE command is identical to SELECT and returns the same 1651 output; however, the selected mailbox is identified as read-only. No 1652 changes to the permanent state of the mailbox, including per-user 1653 state, are permitted. 1655 The text of the tagged OK response to the EXAMINE command MUST begin 1656 with the "[READ-ONLY]" response code. 1658 Example: C: A932 EXAMINE blurdybloop 1659 S: * 17 EXISTS 1660 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1661 S: * OK [UIDNEXT 4392] Predicted next UID 1662 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1663 S: * OK [PERMANENTFLAGS ()] No permanent flags permitted 1664 S: A932 OK [READ-ONLY] EXAMINE completed 1666 6.3.4. CREATE Command 1668 Arguments: mailbox name 1670 Responses: no specific responses for this command 1672 Result: OK - create completed 1673 NO - create failure: can't create mailbox with that name 1674 BAD - command unknown or arguments invalid 1676 The CREATE command creates a mailbox with the given name. An OK 1677 response is returned only if a new mailbox with that name has been 1678 created. It is an error to attempt to create INBOX or a mailbox with 1679 a name that refers to an extant mailbox. Any error in creation will 1680 return a tagged NO response. If a client attempts to create a UTF-8 1681 mailbox name that is not a valid Net-Unicode name, the server MUST 1682 reject the creation or convert the name to Net-Unicode prior to 1683 creating the mailbox. 1685 If the mailbox name is suffixed with the server's hierarchy separator 1686 character (as returned from the server by a LIST command), this is a 1687 declaration that the client intends to create mailbox names under 1688 this name in the hierarchy. Server implementations that do not 1689 require this declaration MUST ignore the declaration. In any case, 1690 the name created is without the trailing hierarchy delimiter. 1692 If the server's hierarchy separator character appears elsewhere in 1693 the name, the server SHOULD create any superior hierarchical names 1694 that are needed for the CREATE command to be successfully completed. 1695 In other words, an attempt to create "foo/bar/zap" on a server in 1696 which "/" is the hierarchy separator character SHOULD create foo/ and 1697 foo/bar/ if they do not already exist. 1699 If a new mailbox is created with the same name as a mailbox which was 1700 deleted, its unique identifiers MUST be greater than any unique 1701 identifiers used in the previous incarnation of the mailbox UNLESS 1702 the new incarnation has a different unique identifier validity value. 1703 See the description of the UID command for more detail. 1705 Example: C: A003 CREATE owatagusiam/ 1706 S: A003 OK CREATE completed 1707 C: A004 CREATE owatagusiam/blurdybloop 1708 S: A004 OK CREATE completed 1710 Note: The interpretation of this example depends on whether "/" 1711 was returned as the hierarchy separator from LIST. If "/" is the 1712 hierarchy separator, a new level of hierarchy named "owatagusiam" 1713 with a member called "blurdybloop" is created. Otherwise, two 1714 mailboxes at the same hierarchy level are created. 1716 6.3.5. DELETE Command 1718 Arguments: mailbox name 1720 Responses: no specific responses for this command 1722 Result: OK - delete completed 1723 NO - delete failure: can't delete mailbox with that name 1724 BAD - command unknown or arguments invalid 1726 The DELETE command permanently removes the mailbox with the given 1727 name. A tagged OK response is returned only if the mailbox has been 1728 deleted. It is an error to attempt to delete INBOX or a mailbox name 1729 that does not exist. 1731 The DELETE command MUST NOT remove inferior hierarchical names. For 1732 example, if a mailbox "foo" has an inferior "foo.bar" (assuming "." 1733 is the hierarchy delimiter character), removing "foo" MUST NOT remove 1734 "foo.bar". It is an error to attempt to delete a name that has 1735 inferior hierarchical names and also has the \Noselect mailbox name 1736 attribute (see the description of the LIST response for more 1737 details). 1739 It is permitted to delete a name that has inferior hierarchical names 1740 and does not have the \Noselect mailbox name attribute. If the 1741 server implementation does not permit deleting the name while 1742 inferior hierarchical names exists then it SHOULD disallow the DELETE 1743 command by returning tagged NO response or it MAY allow the DELETE 1744 command, but sets the \Noselect mailbox name attribute for that name. 1745 In any case, all messages in that mailbox are removed by the DELETE 1746 command. 1748 The value of the highest-used unique identifier of the deleted 1749 mailbox MUST be preserved so that a new mailbox created with the same 1750 name will not reuse the identifiers of the former incarnation, UNLESS 1751 the new incarnation has a different unique identifier validity value. 1752 See the description of the UID command for more detail. 1754 Examples: C: A682 LIST "" * 1755 S: * LIST () "/" blurdybloop 1756 S: * LIST (\Noselect) "/" foo 1757 S: * LIST () "/" foo/bar 1758 S: A682 OK LIST completed 1759 C: A683 DELETE blurdybloop 1760 S: A683 OK DELETE completed 1761 C: A684 DELETE foo 1762 S: A684 NO Name "foo" has inferior hierarchical names 1763 C: A685 DELETE foo/bar 1764 S: A685 OK DELETE Completed 1765 C: A686 LIST "" * 1766 S: * LIST (\Noselect) "/" foo 1767 S: A686 OK LIST completed 1768 C: A687 DELETE foo 1769 S: A687 OK DELETE Completed 1770 C: A82 LIST "" * 1771 S: * LIST () "." blurdybloop 1772 S: * LIST () "." foo 1773 S: * LIST () "." foo.bar 1774 S: A82 OK LIST completed 1775 C: A83 DELETE blurdybloop 1776 S: A83 OK DELETE completed 1777 C: A84 DELETE foo 1778 S: A84 OK DELETE Completed 1779 C: A85 LIST "" * 1780 S: * LIST () "." foo.bar 1781 S: A85 OK LIST completed 1782 C: A86 LIST "" % 1783 S: * LIST (\Noselect) "." foo 1784 S: A86 OK LIST completed 1786 6.3.6. RENAME Command 1788 Arguments: existing mailbox name 1789 new mailbox name 1791 Responses: no specific responses for this command 1793 Result: OK - rename completed 1794 NO - rename failure: can't rename mailbox with that name, 1795 can't rename to mailbox with that name 1796 BAD - command unknown or arguments invalid 1798 The RENAME command changes the name of a mailbox. A tagged OK 1799 response is returned only if the mailbox has been renamed. It is an 1800 error to attempt to rename from a mailbox name that does not exist or 1801 to a mailbox name that already exists. Any error in renaming will 1802 return a tagged NO response. 1804 If the name has inferior hierarchical names, then the inferior 1805 hierarchical names MUST also be renamed. For example, a rename of 1806 "foo" to "zap" will rename "foo/bar" (assuming "/" is the hierarchy 1807 delimiter character) to "zap/bar". 1809 If the server's hierarchy separator character appears in the name, 1810 the server SHOULD create any superior hierarchical names that are 1811 needed for the RENAME command to complete successfully. In other 1812 words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a 1813 server in which "/" is the hierarchy separator character SHOULD 1814 create baz/ and baz/rag/ if they do not already exist. 1816 The value of the highest-used unique identifier of the old mailbox 1817 name MUST be preserved so that a new mailbox created with the same 1818 name will not reuse the identifiers of the former incarnation, UNLESS 1819 the new incarnation has a different unique identifier validity value. 1820 See the description of the UID command for more detail. 1822 Renaming INBOX is permitted, and has special behavior. (Note that 1823 some servers refuse renaming INBOX). It moves all messages in INBOX 1824 to a new mailbox with the given name, leaving INBOX empty. If the 1825 server implementation supports inferior hierarchical names of INBOX, 1826 these are unaffected by a rename of INBOX. 1828 Examples: C: A682 LIST "" * 1829 S: * LIST () "/" blurdybloop 1830 S: * LIST (\Noselect) "/" foo 1831 S: * LIST () "/" foo/bar 1832 S: A682 OK LIST completed 1833 C: A683 RENAME blurdybloop sarasoop 1834 S: A683 OK RENAME completed 1835 C: A684 RENAME foo zowie 1836 S: A684 OK RENAME Completed 1837 C: A685 LIST "" * 1838 S: * LIST () "/" sarasoop 1839 S: * LIST (\Noselect) "/" zowie 1840 S: * LIST () "/" zowie/bar 1841 S: A685 OK LIST completed 1843 C: Z432 LIST "" * 1844 S: * LIST () "." INBOX 1845 S: * LIST () "." INBOX.bar 1846 S: Z432 OK LIST completed 1847 C: Z433 RENAME INBOX old-mail 1848 S: Z433 OK RENAME completed 1849 C: Z434 LIST "" * 1850 S: * LIST () "." INBOX 1851 S: * LIST () "." INBOX.bar 1852 S: * LIST () "." old-mail 1853 S: Z434 OK LIST completed 1855 Note that renaming a mailbox doesn't update subscription information 1856 on the original name. To keep subscription information in sync, the 1857 following sequence of commands can be used: 1859 C: 1001 RENAME X Y 1860 C: 1002 SUBSCRIBE Y 1861 C: 1003 UNSUBSCRIBE X 1863 Note that the above sequence of commands doesn't account for updating 1864 subscription for any children mailboxes of mailbox X. 1866 6.3.7. SUBSCRIBE Command 1868 Arguments: mailbox 1870 Responses: no specific responses for this command 1872 Result: OK - subscribe completed 1873 NO - subscribe failure: can't subscribe to that name 1874 BAD - command unknown or arguments invalid 1876 The SUBSCRIBE command adds the specified mailbox name to the server's 1877 set of "active" or "subscribed" mailboxes as returned by the LIST 1878 (SUBSCRIBED) command. This command returns a tagged OK response if 1879 the subscription is successful or if the mailbox is already 1880 subscribed. 1882 A server MAY validate the mailbox argument to SUBSCRIBE to verify 1883 that it exists. However, it SHOULD NOT unilaterally remove an 1884 existing mailbox name from the subscription list even if a mailbox by 1885 that name no longer exists. 1887 Note: This requirement is because a server site can choose to 1888 routinely remove a mailbox with a well-known name (e.g., "system- 1889 alerts") after its contents expire, with the intention of 1890 recreating it when new contents are appropriate. 1892 Example: C: A002 SUBSCRIBE #news.comp.mail.mime 1893 S: A002 OK SUBSCRIBE completed 1895 6.3.8. UNSUBSCRIBE Command 1897 Arguments: mailbox name 1899 Responses: no specific responses for this command 1901 Result: OK - unsubscribe completed 1902 NO - unsubscribe failure: can't unsubscribe that name 1903 BAD - command unknown or arguments invalid 1905 The UNSUBSCRIBE command removes the specified mailbox name from the 1906 server's set of "active" or "subscribed" mailboxes as returned by the 1907 LIST (SUBSCRIBED) command. This command returns a tagged OK response 1908 if the unsubscription is successful or if the mailbox is not 1909 subscribed. 1911 Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime 1912 S: A002 OK UNSUBSCRIBE completed 1914 6.3.9. LIST Command 1916 Arguments (basic): reference name 1917 mailbox name with possible wildcards 1919 Arguments (extended): selection options (OPTIONAL) 1920 reference name 1921 mailbox patterns 1922 return options (OPTIONAL) 1924 Responses: untagged responses: LIST 1926 Result: OK - list completed 1927 NO - list failure: can't list that reference or name 1928 BAD - command unknown or arguments invalid 1930 The LIST command returns a subset of names from the complete set of 1931 all names available to the client. Zero or more untagged LIST 1932 replies are returned, containing the name attributes, hierarchy 1933 delimiter, name, and possible extension information; see the 1934 description of the LIST reply for more detail. 1936 The LIST command SHOULD return its data quickly, without undue delay. 1937 For example, it SHOULD NOT go to excess trouble to calculate the 1938 \Marked or \Unmarked status or perform other processing; if each name 1939 requires 1 second of processing, then a list of 1200 names would take 1940 20 minutes! 1942 The extended LIST command, originally introduced in [RFC5258], 1943 provides capabilities beyond that of the original IMAP LIST command. 1944 The extended syntax is being used if one or more of the following 1945 conditions is true: 1947 1. if the first word after the command name begins with a 1948 parenthesis ("LIST selection options") 1950 2. if the second word after the command name begins with a 1951 parenthesis ("multiple mailbox patterns") 1953 3. if the LIST command has more than 2 parameters ("LIST return 1954 options") 1956 An empty ("" string) reference name argument indicates that the 1957 mailbox name is interpreted as by SELECT. The returned mailbox names 1958 MUST match the supplied mailbox name pattern(s). A non-empty 1959 reference name argument is the name of a mailbox or a level of 1960 mailbox hierarchy, and indicates the context in which the mailbox 1961 name is interpreted. Clients SHOULD use the empty reference 1962 argument. 1964 In the basic syntax only, an empty ("" string) mailbox name argument 1965 is a special request to return the hierarchy delimiter and the root 1966 name of the name given in the reference. The value returned as the 1967 root MAY be the empty string if the reference is non-rooted or is an 1968 empty string. In all cases, a hierarchy delimiter (or NIL if there 1969 is no hierarchy) is returned. This permits a client to get the 1970 hierarchy delimiter (or find out that the mailbox names are flat) 1971 even when no mailboxes by that name currently exist. 1973 In the extended syntax, any mailbox name arguments that are empty 1974 strings are ignored. There is no special meaning for empty mailbox 1975 names when the extended syntax is used. 1977 The reference and mailbox name arguments are interpreted into a 1978 canonical form that represents an unambiguous left-to-right 1979 hierarchy. The returned mailbox names will be in the interpreted 1980 form, that we call "canonical LIST pattern" later in this document. 1981 To define the term "canonical LIST pattern" formally: it refers to 1982 the canonical pattern constructed internally by the server from the 1983 reference and mailbox name arguments. 1985 Note: The interpretation of the reference argument is 1986 implementation-defined. It depends upon whether the server 1987 implementation has a concept of the "current working directory" 1988 and leading "break out characters", which override the current 1989 working directory. 1991 For example, on a server which exports a UNIX or NT filesystem, 1992 the reference argument contains the current working directory, and 1993 the mailbox name argument would contain the name as interpreted in 1994 the current working directory. 1996 If a server implementation has no concept of break out characters, 1997 the canonical form is normally the reference name appended with 1998 the mailbox name. Note that if the server implements the 1999 namespace convention (Section 5.1.2.1), "#" is a break out 2000 character and must be treated as such. 2002 If the reference argument is not a level of mailbox hierarchy 2003 (that is, it is a \NoInferiors name), and/or the reference 2004 argument does not end with the hierarchy delimiter, it is 2005 implementation-dependent how this is interpreted. For example, a 2006 reference of "foo/bar" and mailbox name of "rag/baz" could be 2007 interpreted as "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/ 2008 baz". A client SHOULD NOT use such a reference argument except at 2009 the explicit request of the user. A hierarchical browser MUST NOT 2010 make any assumptions about server interpretation of the reference 2011 unless the reference is a level of mailbox hierarchy AND ends with 2012 the hierarchy delimiter. 2014 Any part of the reference argument that is included in the 2015 interpreted form SHOULD prefix the interpreted form. It SHOULD also 2016 be in the same form as the reference name argument. This rule 2017 permits the client to determine if the returned mailbox name is in 2018 the context of the reference argument, or if something about the 2019 mailbox argument overrode the reference argument. Without this rule, 2020 the client would have to have knowledge of the server's naming 2021 semantics including what characters are "breakouts" that override a 2022 naming context. 2024 For example, here are some examples of how references 2025 and mailbox names might be interpreted on a UNIX-based 2026 server: 2028 Reference Mailbox Name Interpretation 2029 ------------ ------------ -------------- 2030 ~smith/Mail/ foo.* ~smith/Mail/foo.* 2031 archive/ % archive/% 2032 #news. comp.mail.* #news.comp.mail.* 2033 ~smith/Mail/ /usr/doc/foo /usr/doc/foo 2034 archive/ ~fred/Mail/* ~fred/Mail/* 2036 The first three examples demonstrate interpretations in 2037 the context of the reference argument. Note that 2038 "~smith/Mail" SHOULD NOT be transformed into something 2039 like "/u2/users/smith/Mail", or it would be impossible 2040 for the client to determine that the interpretation was 2041 in the context of the reference. 2043 The character "*" is a wildcard, and matches zero or more characters 2044 at this position. The character "%" is similar to "*", but it does 2045 not match a hierarchy delimiter. If the "%" wildcard is the last 2046 character of a mailbox name argument, matching levels of hierarchy 2047 are also returned. If these levels of hierarchy are not also 2048 selectable mailboxes, they are returned with the \Noselect mailbox 2049 name attribute (see the description of the LIST response for more 2050 details). 2052 If multiple mailbox patterns are used (in the extended syntax), a 2053 mailbox matches if it matches at least one mailbox pattern. If a 2054 mailbox matches more than one pattern, it is still only returned 2055 once. Any syntactically valid pattern that is not accepted by a 2056 server for any reason MUST be silently ignored. 2058 Selection options tell the server to limit the mailbox names that are 2059 selected by the LIST operation. If selection options are used, the 2060 mailboxes returned are those that match both the list of canonical 2061 LIST patterns and the selection options. Unless a particular 2062 selection option provides special rules, the selection options are 2063 cumulative: a mailbox that matches the mailbox patterns is selected 2064 only if it also matches all of the selection options. (An example of 2065 a selection option with special rules is the RECURSIVEMATCH option.) 2067 Return options control what information is returned for each matched 2068 mailbox. Return options MUST NOT cause the server to report 2069 information about additional mailbox names other than those that 2070 match the canonical LIST patterns and selection options. If no 2071 return options are specified, the client is only expecting 2072 information about mailbox attributes. The server MAY return other 2073 information about the matched mailboxes, and clients MUST be able to 2074 handle that situation. 2076 Initial selection options and return options are defined in the 2077 following subsections, and new ones will also be defined in 2078 extensions. Initial options defined in this document MUST be 2079 supported. Each non-initial option will be enabled by a capability 2080 string (one capability may enable multiple options), and a client 2081 MUST NOT send an option for which the server has not advertised 2082 support. A server MUST respond to options it does not recognize with 2083 a BAD response. The client SHOULD NOT specify any option more than 2084 once; however, if the client does this, the server MUST act as if it 2085 received the option only once. The order in which options are 2086 specified by the client is not significant. 2088 In general, each selection option except RECURSIVEMATCH will have a 2089 corresponding return option. The REMOTE selection option is an 2090 anomaly in this regard, and does not have a corresponding return 2091 option. That is because it expands, rather than restricts, the set 2092 of mailboxes that are returned. Future extensions to this 2093 specification should keep parallelism in mind and define a pair of 2094 corresponding options. 2096 Server implementations are permitted to "hide" otherwise accessible 2097 mailboxes from the wildcard characters, by preventing certain 2098 characters or names from matching a wildcard in certain situations. 2099 For example, a UNIX-based server might restrict the interpretation of 2100 "*" so that an initial "/" character does not match. 2102 The special name INBOX is included in the output from LIST, if INBOX 2103 is supported by this server for this user and if the uppercase string 2104 "INBOX" matches the interpreted reference and mailbox name arguments 2105 with wildcards as described above. The criteria for omitting INBOX 2106 is whether SELECT INBOX will return failure; it is not relevant 2107 whether the user's real INBOX resides on this or some other server. 2109 6.3.9.1. LIST Selection Options 2111 The selection options defined in this specification are as follows: 2113 SUBSCRIBED - causes the LIST command to list subscribed names, 2114 rather than the existing mailboxes. This will often be a subset 2115 of the actual mailboxes. It's also possible for this list to 2116 contain the names of mailboxes that don't exist. In any case, the 2117 list MUST include exactly those mailbox names that match the 2118 canonical list pattern and are subscribed to. 2120 This option defines a mailbox attribute, "\Subscribed", that 2121 indicates that a mailbox name is subscribed to. The "\Subscribed" 2122 attribute MUST be supported and MUST be accurately computed when 2123 the SUBSCRIBED selection option is specified. 2125 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 2126 return option (see below). 2128 REMOTE - causes the LIST command to show remote mailboxes as well as 2129 local ones, as described in [RFC2193]. This option is intended to 2130 replace the RLIST command and, in conjunction with the SUBSCRIBED 2131 selection option, the RLSUB command. Servers that don't support 2132 remote mailboxes just ignore this option. 2134 This option defines a mailbox attribute, "\Remote", that indicates 2135 that a mailbox is a remote mailbox. The "\Remote" attribute MUST 2136 be accurately computed when the REMOTE option is specified. 2138 The REMOTE selection option has no interaction with other options. 2139 Its effect is to tell the server to apply the other options, if 2140 any, to remote mailboxes, in addition to local ones. In 2141 particular, it has no interaction with RECURSIVEMATCH (see below). 2142 A request for (REMOTE RECURSIVEMATCH) is invalid, because a 2143 request for (RECURSIVEMATCH) is also invalid. A request for 2144 (REMOTE RECURSIVEMATCH SUBSCRIBED) is asking for all subscribed 2145 mailboxes, both local and remote. 2147 RECURSIVEMATCH - this option forces the server to return information 2148 about parent mailboxes that don't match other selection options, 2149 but have some submailboxes that do. Information about children is 2150 returned in the CHILDINFO extended data item, as described in 2151 Section 6.3.9.6. 2153 Note 1: In order for a parent mailbox to be returned, it still has 2154 to match the canonical LIST pattern. 2156 Note 2: When returning the CHILDINFO extended data item, it 2157 doesn't matter whether or not the submailbox matches the canonical 2158 LIST pattern. See also example 9 in Section 6.3.9.7. 2160 The RECURSIVEMATCH option MUST NOT occur as the only selection 2161 option (or only with REMOTE), as it only makes sense when other 2162 selection options are also used. The server MUST return BAD 2163 tagged response in such case. 2165 Note that even if the RECURSIVEMATCH option is specified, the 2166 client MUST still be able to handle a case when a CHILDINFO 2167 extended data item is returned and there are no submailboxes that 2168 meet the selection criteria of the subsequent LIST command, as 2169 they can be deleted/renamed after the LIST response was sent, but 2170 before the client had a chance to access them. 2172 6.3.9.2. LIST Return Options 2174 The return options defined in this specification are as follows: 2176 SUBSCRIBED - causes the LIST command to return subscription state 2177 for all matching mailbox names. The "\Subscribed" attribute MUST 2178 be supported and MUST be accurately computed when the SUBSCRIBED 2179 return option is specified. Further, all mailbox flags MUST be 2180 accurately computed (this differs from the behavior of the 2181 obsolete LSUB command from IMAP4rev1). 2183 CHILDREN - requests mailbox child information as originally proposed 2184 in [RFC3348]. See Section 6.3.9.5, below, for details. This 2185 option MUST be supported by all servers. 2187 STATUS - requests STATUS response for each matching mailbox. 2189 This option takes STATUS data items as parameters. For each 2190 selectable mailbox matching the list pattern and selection 2191 options, the server MUST return an untagged LIST response 2192 followed by an untagged STATUS response containing the 2193 information requested in the STATUS return option. 2195 If an attempted STATUS for a listed mailbox fails because the 2196 mailbox can't be selected (e.g., if the "l" ACL right [RFC4314] 2197 is granted to the mailbox and the "r" right is not granted, or 2198 due to a race condition between LIST and STATUS changing the 2199 mailbox to \NoSelect), the STATUS response MUST NOT be returned 2200 and the LIST response MUST include the \NoSelect attribute. 2201 This means the server may have to buffer the LIST reply until 2202 it has successfully looked up the necessary STATUS information. 2204 If the server runs into unexpected problems while trying to 2205 look up the STATUS information, it MAY drop the corresponding 2206 STATUS reply. In such a situation, the LIST command would 2207 still return a tagged OK reply. 2209 6.3.9.3. General Principles for Returning LIST Responses 2211 This section outlines several principles that can be used by server 2212 implementations of this document to decide whether a LIST response 2213 should be returned, as well as how many responses and what kind of 2214 information they may contain. 2216 1. At most one LIST response should be returned for each mailbox 2217 name that matches the canonical LIST pattern. Server 2218 implementors must not assume that clients will be able to 2219 assemble mailbox attributes and other information returned in 2220 multiple LIST responses. 2222 2. There are only two reasons for including a matching mailbox name 2223 in the responses to the LIST command (note that the server is 2224 allowed to return unsolicited responses at any time, and such 2225 responses are not governed by this rule): 2227 A. The mailbox name also satisfies the selection criteria. 2229 B. The mailbox name doesn't satisfy the selection criteria, but 2230 it has at least one descendant mailbox name that satisfies 2231 the selection criteria and that doesn't match the canonical 2232 LIST pattern. 2234 For more information on this case, see the CHILDINFO extended 2235 data item described in Section 6.3.9.6. Note that the 2236 CHILDINFO extended data item can only be returned when the 2237 RECURSIVEMATCH selection option is specified. 2239 3. Attributes returned in the same LIST response must be treated 2240 additively. For example, the following response 2242 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2244 means that the "Fruit/Peach" mailbox doesn't exist, but it is 2245 subscribed. 2247 6.3.9.4. Additional LIST-related Requirements on Clients 2249 All clients MUST treat a LIST attribute with a stronger meaning as 2250 implying any attribute that can be inferred from it. (See 2251 Section 7.2.3 for the list of currently defined attributes). For 2252 example, the client must treat the presence of the \NoInferiors 2253 attribute as if the \HasNoChildren attribute was also sent by the 2254 server. 2256 The following table summarizes inference rules. 2258 +--------------------+-------------------+ 2259 | returned attribute | implied attribute | 2260 +--------------------+-------------------+ 2261 | \NoInferiors | \HasNoChildren | 2262 | \NonExistent | \NoSelect | 2263 +--------------------+-------------------+ 2265 6.3.9.5. The CHILDREN Return Option 2267 The CHILDREN return option implements the Child Mailbox Extension, 2268 originally proposed by Mike Gahrns and Raymond Cheng, of Microsoft 2269 Corporation. Most of the information in this section is taken 2270 directly from their original specification [RFC3348]. The CHILDREN 2271 return option is simply an indication that the client wants this 2272 information; a server MAY provide it even if the option is not 2273 specified. 2275 Many IMAP4 clients present to the user a hierarchical view of the 2276 mailboxes that a user has access to. Rather than initially 2277 presenting to the user the entire mailbox hierarchy, it is often 2278 preferable to show to the user a collapsed outline list of the 2279 mailbox hierarchy (particularly if there is a large number of 2280 mailboxes). The user can then expand the collapsed outline hierarchy 2281 as needed. It is common to include within the collapsed hierarchy a 2282 visual clue (such as a ''+'') to indicate that there are child 2283 mailboxes under a particular mailbox. When the visual clue is 2284 clicked, the hierarchy list is expanded to show the child mailboxes. 2285 The CHILDREN return option provides a mechanism for a client to 2286 efficiently determine whether a particular mailbox has children, 2287 without issuing a LIST "" * or a LIST "" % for each mailbox name. 2288 The CHILDREN return option defines two new attributes that MUST be 2289 returned within a LIST response: \HasChildren and \HasNoChildren. 2290 Although these attributes MAY be returned in response to any LIST 2291 command, the CHILDREN return option is provided to indicate that the 2292 client particularly wants this information. If the CHILDREN return 2293 option is present, the server MUST return these attributes even if 2294 their computation is expensive. 2296 \HasChildren 2298 The presence of this attribute indicates that the mailbox has 2299 child mailboxes. A server SHOULD NOT set this attribute if 2300 there are child mailboxes and the user does not have permission 2301 to access any of them. In this case, \HasNoChildren SHOULD be 2302 used. In many cases, however, a server may not be able to 2303 efficiently compute whether a user has access to any child 2304 mailbox. Note that even though the \HasChildren attribute for a 2305 mailbox must be correct at the time of processing of the 2306 mailbox, a client must be prepared to deal with a situation when 2307 a mailbox is marked with the \HasChildren attribute, but no 2308 child mailbox appears in the response to the LIST command. This 2309 might happen, for example, due to children mailboxes being 2310 deleted or made inaccessible to the user (using access control) 2311 by another client before the server is able to list them. 2313 \HasNoChildren 2315 The presence of this attribute indicates that the mailbox has NO 2316 child mailboxes that are accessible to the currently 2317 authenticated user. 2319 It is an error for the server to return both a \HasChildren and a 2320 \HasNoChildren attribute in the same LIST response. 2322 Note: the \HasNoChildren attribute should not be confused with the 2323 the \NoInferiors attribute, which indicates that no child mailboxes 2324 exist now and none can be created in the future. 2326 6.3.9.6. CHILDINFO Extended Data Item 2328 The CHILDINFO extended data item MUST NOT be returned unless the 2329 client has specified the RECURSIVEMATCH selection option. 2331 The CHILDINFO extended data item in a LIST response describes the 2332 selection criteria that has caused it to be returned and indicates 2333 that the mailbox has at least one descendant mailbox that matches the 2334 selection criteria. 2336 Note: Some servers allow for mailboxes to exist without requiring 2337 their parent to exist. For example, a mailbox "Customers/ABC" can 2338 exist while the mailbox "Customers" does not. As CHILDINFO extended 2339 data item is not allowed if the RECURSIVEMATCH selection option is 2340 not specified, such servers SHOULD use the "\NonExistent 2341 \HasChildren" attribute pair to signal to the client that there is a 2342 descendant mailbox that matches the selection criteria. See example 2343 11 in Section 6.3.9.7. 2345 The returned selection criteria allow the client to distinguish a 2346 solicited response from an unsolicited one, as well as to distinguish 2347 among solicited responses caused by multiple pipelined LIST commands 2348 that specify different criteria. 2350 Servers SHOULD ONLY return a non-matching mailbox name along with 2351 CHILDINFO if at least one matching child is not also being returned. 2352 That is, servers SHOULD suppress redundant CHILDINFO responses. 2354 Examples 8 and 10 in Section 6.3.9.7 demonstrate the difference 2355 between present CHILDINFO extended data item and the "\HasChildren" 2356 attribute. 2358 The following table summarizes interaction between the "\NonExistent" 2359 attribute and CHILDINFO (the first column indicates whether the 2360 parent mailbox exists): 2362 +--------+--------------+--------------------+----------------------+ 2363 | exists | meets the | has a child that | returned LIST- | 2364 | | selection | meets the | EXTENDED attributes | 2365 | | criteria | selection criteria | and CHILDINFO | 2366 +--------+--------------+--------------------+----------------------+ 2367 | no | no | no | no LIST response | 2368 | | | | returned | 2369 | yes | no | no | no LIST response | 2370 | | | | returned | 2371 | no | yes | no | (\NonExistent | 2372 | | | | ) | 2373 | yes | yes | no | () | 2374 | no | no | yes | (\NonExistent) + | 2375 | | | | CHILDINFO | 2376 | yes | no | yes | () + CHILDINFO | 2377 | no | yes | yes | (\NonExistent | 2378 | | | | ) + CHILDINFO | 2379 | yes | yes | yes | () + CHILDINFO | 2380 +--------+--------------+--------------------+----------------------+ 2382 where is one or more attributes that correspond to the 2383 selection criteria; for example, for the SUBSCRIBED option the 2384 is \Subscribed. 2386 6.3.9.7. LIST Command Examples 2388 This example shows some uses of the basic LIST command: 2390 Example: C: A101 LIST "" "" 2391 S: * LIST (\Noselect) "/" "" 2392 S: A101 OK LIST Completed 2393 C: A102 LIST #news.comp.mail.misc "" 2394 S: * LIST (\Noselect) "." #news. 2395 S: A102 OK LIST Completed 2396 C: A103 LIST /usr/staff/jones "" 2397 S: * LIST (\Noselect) "/" / 2398 S: A103 OK LIST Completed 2399 C: A202 LIST ~/Mail/ % 2400 S: * LIST (\Noselect) "/" ~/Mail/foo 2401 S: * LIST () "/" ~/Mail/meetings 2402 S: A202 OK LIST completed 2404 Extended examples: 2406 1: The first example shows the complete local hierarchy that will 2407 be used for the other examples. 2409 C: A01 LIST "" "*" 2410 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2411 S: * LIST () "/" "Fruit" 2412 S: * LIST () "/" "Fruit/Apple" 2413 S: * LIST () "/" "Fruit/Banana" 2414 S: * LIST () "/" "Tofu" 2415 S: * LIST () "/" "Vegetable" 2416 S: * LIST () "/" "Vegetable/Broccoli" 2417 S: * LIST () "/" "Vegetable/Corn" 2418 S: A01 OK done 2420 2: In the next example, we will see the subscribed mailboxes. This 2421 is similar to, but not equivalent with, . Note 2422 that the mailbox called "Fruit/Peach" is subscribed to, but does 2423 not actually exist (perhaps it was deleted while still 2424 subscribed). The "Fruit" mailbox is not subscribed to, but it 2425 has two subscribed children. The "Vegetable" mailbox is 2426 subscribed and has two children; one of them is subscribed as 2427 well. 2429 C: A02 LIST (SUBSCRIBED) "" "*" 2430 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2431 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2432 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2433 S: * LIST (\Subscribed) "/" "Vegetable" 2434 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2435 S: A02 OK done 2437 3: The next example shows the use of the CHILDREN option. The 2438 client, without having to list the second level of hierarchy, 2439 now knows which of the top-level mailboxes have submailboxes 2440 (children) and which do not. Note that it's not necessary for 2441 the server to return the \HasNoChildren attribute for the inbox, 2442 because the \NoInferiors attribute already implies that, and has 2443 a stronger meaning. 2445 C: A03 LIST () "" "%" RETURN (CHILDREN) 2446 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2447 S: * LIST (\HasChildren) "/" "Fruit" 2448 S: * LIST (\HasNoChildren) "/" "Tofu" 2449 S: * LIST (\HasChildren) "/" "Vegetable" 2450 S: A03 OK done 2452 4: In this example, we see more mailboxes that reside on another 2453 server. This is similar to the command . 2455 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 2456 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2457 S: * LIST (\HasChildren) "/" "Fruit" 2458 S: * LIST (\HasNoChildren) "/" "Tofu" 2459 S: * LIST (\HasChildren) "/" "Vegetable" 2460 S: * LIST (\Remote) "/" "Bread" 2461 S: * LIST (\HasChildren \Remote) "/" "Meat" 2462 S: A04 OK done 2464 5: The following example also requests the server to include 2465 mailboxes that reside on another server. The server returns 2466 information about all mailboxes that are subscribed. This is 2467 similar to the command . We also see the use of 2468 two selection options. 2470 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 2471 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2472 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2473 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2474 S: * LIST (\Subscribed) "/" "Vegetable" 2475 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2476 S: * LIST (\Remote \Subscribed) "/" "Bread" 2477 S: A05 OK done 2479 6: The following example requests the server to include mailboxes 2480 that reside on another server. The server is asked to return 2481 subscription information for all returned mailboxes. This is 2482 different from the example above. 2484 Note that the output of this command is not a superset of the 2485 output in the previous example, as it doesn't include LIST 2486 response for the non-existent "Fruit/Peach". 2488 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 2489 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2490 S: * LIST () "/" "Fruit" 2491 S: * LIST () "/" "Fruit/Apple" 2492 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2493 S: * LIST () "/" "Tofu" 2494 S: * LIST (\Subscribed) "/" "Vegetable" 2495 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2496 S: * LIST () "/" "Vegetable/Corn" 2497 S: * LIST (\Remote \Subscribed) "/" "Bread" 2498 S: * LIST (\Remote) "/" "Meat" 2499 S: A06 OK done 2501 7: In the following example, the client has specified multiple 2502 mailbox patterns. Note that this example does not use the 2503 mailbox hierarchy used in the previous examples. 2505 C: BBB LIST "" ("INBOX" "Drafts" "Sent/%") 2506 S: * LIST () "/" "INBOX" 2507 S: * LIST (\NoInferiors) "/" "Drafts" 2508 S: * LIST () "/" "Sent/March2004" 2509 S: * LIST (\Marked) "/" "Sent/December2003" 2510 S: * LIST () "/" "Sent/August2004" 2511 S: BBB OK done 2513 8: The following example demonstrates the difference between the 2514 \HasChildren attribute and the CHILDINFO extended data item. 2516 Let's assume there is the following hierarchy: 2518 C: C01 LIST "" "*" 2519 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2520 S: * LIST () "/" "Foo" 2521 S: * LIST () "/" "Foo/Bar" 2522 S: * LIST () "/" "Foo/Baz" 2523 S: * LIST () "/" "Moo" 2524 S: C01 OK done 2526 If the client asks RETURN (CHILDREN), it will get this: 2528 C: CA3 LIST "" "%" RETURN (CHILDREN) 2529 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2530 S: * LIST (\HasChildren) "/" "Foo" 2531 S: * LIST (\HasNoChildren) "/" "Moo" 2532 S: CA3 OK done 2534 A) Let's also assume that the mailbox "Foo/Baz" is the only 2535 subscribed mailbox. Then we get this result: 2537 C: C02 LIST (SUBSCRIBED) "" "*" 2538 S: * LIST (\Subscribed) "/" "Foo/Baz" 2539 S: C02 OK done 2541 Now, if the client issues , the server 2542 will return no mailboxes (as the mailboxes "Moo", "Foo", and 2543 "Inbox" are NOT subscribed). However, if the client issues 2544 this: 2546 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2547 S: * LIST () "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2548 S: C04 OK done 2550 (i.e., the mailbox "Foo" is not subscribed, but it has a child 2551 that is.) 2553 A1) If the mailbox "Foo" had also been subscribed, the last 2554 command would return this: 2556 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2557 S: * LIST (\Subscribed) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2558 S: C04 OK done 2560 or even this: 2562 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2563 S: * LIST (\Subscribed \HasChildren) "/" "Foo" ("CHILDINFO" 2564 ("SUBSCRIBED")) 2565 S: C04 OK done 2567 A2) If we assume instead that the mailbox "Foo" is not part of 2568 the original hierarchy and is not subscribed, the last command 2569 will give this result: 2571 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2572 S: * LIST (\NonExistent) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2573 S: C04 OK done 2574 B) Now, let's assume that no mailbox is subscribed. In this 2575 case, the command will 2576 return no responses, as there are no subscribed children (even 2577 though "Foo" has children). 2579 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 2580 are subscribed. In that case, we see this result: 2582 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 2583 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 2584 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 2585 S: C04 OK done 2587 (which means that the mailbox "Foo" has children, but none of 2588 them is subscribed). 2590 9: The following example demonstrates that the CHILDINFO extended 2591 data item is returned whether or not children mailboxes match 2592 the canonical LIST pattern. 2594 Let's assume there is the following hierarchy: 2596 C: D01 LIST "" "*" 2597 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2598 S: * LIST () "/" "foo2" 2599 S: * LIST () "/" "foo2/bar1" 2600 S: * LIST () "/" "foo2/bar2" 2601 S: * LIST () "/" "baz2" 2602 S: * LIST () "/" "baz2/bar2" 2603 S: * LIST () "/" "baz2/bar22" 2604 S: * LIST () "/" "baz2/bar222" 2605 S: * LIST () "/" "eps2" 2606 S: * LIST () "/" "eps2/mamba" 2607 S: * LIST () "/" "qux2/bar2" 2608 S: D01 OK done 2610 And that the following mailboxes are subscribed: 2612 C: D02 LIST (SUBSCRIBED) "" "*" 2613 S: * LIST (\Subscribed) "/" "foo2/bar1" 2614 S: * LIST (\Subscribed) "/" "foo2/bar2" 2615 S: * LIST (\Subscribed) "/" "baz2/bar2" 2616 S: * LIST (\Subscribed) "/" "baz2/bar22" 2617 S: * LIST (\Subscribed) "/" "baz2/bar222" 2618 S: * LIST (\Subscribed) "/" "eps2" 2619 S: * LIST (\Subscribed) "/" "eps2/mamba" 2620 S: * LIST (\Subscribed) "/" "qux2/bar2" 2621 S: D02 OK done 2622 The client issues the following command first: 2624 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 2625 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2626 S: * LIST (\Subscribed) "/" "foo2/bar2" 2627 S: * LIST (\Subscribed) "/" "baz2/bar2" 2628 S: * LIST (\Subscribed) "/" "baz2/bar22" 2629 S: * LIST (\Subscribed) "/" "baz2/bar222" 2630 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2631 S: * LIST (\Subscribed) "/" "qux2/bar2" 2632 S: D03 OK done 2634 and the server may also include (but this would violate a SHOULD 2635 NOT in Section 3.5, because CHILDINFO is redundant) 2637 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2638 S: * LIST (\NonExistent) "/" "qux2" ("CHILDINFO" ("SUBSCRIBED")) 2640 The CHILDINFO extended data item is returned for mailboxes 2641 "foo2", "baz2", and "eps2", because all of them have subscribed 2642 children, even though for the mailbox "foo2" only one of the two 2643 subscribed children matches the pattern, for the mailbox "baz2" 2644 all the subscribed children match the pattern, and for the 2645 mailbox "eps2" none of the subscribed children matches the 2646 pattern. 2648 Note that if the client issues 2650 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 2651 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2652 S: * LIST (\Subscribed) "/" "foo2/bar1" 2653 S: * LIST (\Subscribed) "/" "foo2/bar2" 2654 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2655 S: * LIST (\Subscribed) "/" "baz2/bar2" 2656 S: * LIST (\Subscribed) "/" "baz2/bar22" 2657 S: * LIST (\Subscribed) "/" "baz2/bar222" 2658 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2659 S: * LIST (\Subscribed) "/" "eps2/mamba" 2660 S: * LIST (\Subscribed) "/" "qux2/bar2" 2661 S: D03 OK done 2663 The LIST responses for mailboxes "foo2", "baz2", and "eps2" 2664 still have the CHILDINFO extended data item, even though this 2665 information is redundant and the client can determine it by 2666 itself. 2668 10: The following example shows usage of extended syntax for mailbox 2669 pattern. It also demonstrates that the presence of the 2670 CHILDINFO extended data item doesn't necessarily imply 2671 \HasChildren. 2673 C: a1 LIST "" ("foo") 2674 S: * LIST () "/" foo 2675 S: a1 OK done 2677 C: a2 LIST (SUBSCRIBED) "" "foo/*" 2678 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 2679 S: a2 OK done 2681 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN (CHILDREN) 2682 S: * LIST (\HasNoChildren) "/" foo ("CHILDINFO" ("SUBSCRIBED")) 2683 S: a3 OK done 2685 11: The following example shows how a server that supports missing 2686 mailbox hierarchy elements can signal to a client that didn't 2687 specify the RECURSIVEMATCH selection option that there is a 2688 child mailbox that matches the selection criteria. 2690 C: a1 LIST (REMOTE) "" * 2691 S: * LIST () "/" music/rock 2692 S: * LIST (\Remote) "/" also/jazz 2693 S: a1 OK done 2695 C: a2 LIST () "" % 2696 S: * LIST (\NonExistent \HasChildren) "/" music 2697 S: a2 OK done 2699 C: a3 LIST (REMOTE) "" % 2700 S: * LIST (\NonExistent \HasChildren) "/" music 2701 S: * LIST (\NonExistent \HasChildren) "/" also 2702 S: a3 OK done 2704 C: a3.1 LIST "" (% music/rock) 2705 S: * LIST () "/" music/rock 2706 S: a3.1 OK done 2708 Because "music/rock" is the only mailbox under "music", there's 2709 no need for the server to also return "music". However clients 2710 must handle both cases. 2712 12: The following examples show use of STATUS return option. 2714 C: A01 LIST "" % RETURN (STATUS (MESSAGES UNSEEN)) 2715 S: * LIST () "." "INBOX" 2716 S: * STATUS "INBOX" (MESSAGES 17 UNSEEN 16) 2717 S: * LIST () "." "foo" 2718 S: * STATUS "foo" (MESSAGES 30 UNSEEN 29) 2719 S: * LIST (\NoSelect) "." "bar" 2720 S: A01 OK List completed. 2722 The "bar" mailbox isn't selectable, so it has no STATUS reply. 2724 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (STATUS 2725 (MESSAGES)) 2726 S: * LIST (\Subscribed) "." "INBOX" 2727 S: * STATUS "INBOX" (MESSAGES 17) 2728 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED")) 2729 S: A02 OK List completed. 2731 The LIST reply for "foo" is returned because it has matching 2732 children, but no STATUS reply is returned because "foo" itself 2733 doesn't match the selection criteria. 2735 6.3.10. NAMESPACE Command 2737 Arguments: none 2739 Responses: REQUIRED untagged responses: NAMESPACE 2741 Result: OK - command completed 2742 NO - Can't complete the command 2743 BAD - arguments invalid 2745 The NAMESPACE command causes a single ungagged NAMESPACE response to 2746 be returned. The untagged NAMESPACE response contains the prefix and 2747 hierarchy delimiter to the server's Personal Namespace(s), Other 2748 Users' Namespace(s), and Shared Namespace(s) that the server wishes 2749 to expose. The response will contain a NIL for any namespace class 2750 that is not available. Namespace-Response-Extensions ABNF non 2751 terminal is defined for extensibility and MAY be included in the 2752 response. 2754 Example 1: 2756 In this example a server supports a single personal namespace. No 2757 leading prefix is used on personal mailboxes and "/" is the hierarchy 2758 delimiter. 2760 C: A001 NAMESPACE 2761 S: * NAMESPACE (("" "/")) NIL NIL 2762 S: A001 OK NAMESPACE command completed 2764 Example 2: 2766 A user logged on anonymously to a server. No personal mailboxes are 2767 associated with the anonymous user and the user does not have access 2768 to the Other Users' Namespace. No prefix is required to access 2769 shared mailboxes and the hierarchy delimiter is "." 2771 C: A001 NAMESPACE 2772 S: * NAMESPACE NIL NIL (("" ".")) 2773 S: A001 OK NAMESPACE command completed 2775 Example 3: 2777 A server that contains a Personal Namespace and a single Shared 2778 Namespace. 2780 C: A001 NAMESPACE 2781 S: * NAMESPACE (("" "/")) NIL (("Public Folders/" "/")) 2782 S: A001 OK NAMESPACE command completed 2784 Example 4: 2786 A server that contains a Personal Namespace, Other Users' Namespace 2787 and multiple Shared Namespaces. Note that the hierarchy delimiter 2788 used within each namespace can be different. 2790 C: A001 NAMESPACE 2791 S: * NAMESPACE (("" "/")) (("~" "/")) (("#shared/" "/") 2792 ("#public/" "/")("#ftp/" "/")("#news." ".")) 2793 S: A001 OK NAMESPACE command completed 2795 The prefix string allows a client to do things such as automatically 2796 creating personal mailboxes or LISTing all available mailboxes within 2797 a namespace. 2799 Example 5: 2801 A server that supports only the Personal Namespace, with a leading 2802 prefix of INBOX to personal mailboxes and a hierarchy delimiter of 2803 "." 2804 C: A001 NAMESPACE 2805 S: * NAMESPACE (("INBOX." ".")) NIL NIL 2806 S: A001 OK NAMESPACE command completed 2808 < Automatically create a mailbox to store sent items.> 2810 C: A002 CREATE "INBOX.Sent Mail" 2811 S: A002 OK CREATE command completed 2813 Although typically a server will support only a single Personal 2814 Namespace, and a single Other User's Namespace, circumstances exist 2815 where there MAY be multiples of these, and a client MUST be prepared 2816 for them. If a client is configured such that it is required to 2817 create a certain mailbox, there can be circumstances where it is 2818 unclear which Personal Namespaces it should create the mailbox in. 2819 In these situations a client SHOULD let the user select which 2820 namespaces to create the mailbox in or just use the first personal 2821 namespace. 2823 Example 6: 2825 In this example, a server supports 2 Personal Namespaces. In 2826 addition to the regular Personal Namespace, the user has an 2827 additional personal namespace to allow access to mailboxes in an MH 2828 format mailstore. 2830 The client is configured to save a copy of all mail sent by the user 2831 into a mailbox called 'Sent Mail'. Furthermore, after a message is 2832 deleted from a mailbox, the client is configured to move that message 2833 to a mailbox called 'Deleted Items'. 2835 Note that this example demonstrates how some extension flags can be 2836 passed to further describe the #mh namespace. 2838 C: A001 NAMESPACE 2839 S: * NAMESPACE (("" "/")("#mh/" "/" "X-PARAM" 2840 ("FLAG1" "FLAG2"))) NIL NIL 2841 S: A001 OK NAMESPACE command completed 2843 < It is desired to keep only one copy of sent mail. 2844 It is unclear which Personal Namespace the client 2845 should use to create the 'Sent Mail' mailbox. 2846 The user is prompted to select a namespace and only 2847 one 'Sent Mail' mailbox is created. > 2849 C: A002 CREATE "Sent Mail" 2850 S: A002 OK CREATE command completed 2852 < The client is designed so that it keeps two 2853 'Deleted Items' mailboxes, one for each namespace. > 2855 C: A003 CREATE "Delete Items" 2856 S: A003 OK CREATE command completed 2858 C: A004 CREATE "#mh/Deleted Items" 2859 S: A004 OK CREATE command completed 2861 The next level of hierarchy following the Other Users' Namespace 2862 prefix SHOULD consist of , where is a user name 2863 as per the LOGIN or AUTHENTICATE command. 2865 A client can construct a LIST command by appending a "%" to the Other 2866 Users' Namespace prefix to discover the Personal Namespaces of other 2867 users that are available to the currently authenticated user. 2869 In response to such a LIST command, a server SHOULD NOT return user 2870 names that have not granted access to their personal mailboxes to the 2871 user in question. 2873 A server MAY return a LIST response containing only the names of 2874 users that have explicitly granted access to the user in question. 2876 Alternatively, a server MAY return NO to such a LIST command, 2877 requiring that a user name be included with the Other Users' 2878 Namespace prefix before listing any other user's mailboxes. 2880 Example 7: 2882 A server that supports providing a list of other user's mailboxes 2883 that are accessible to the currently logged on user. 2885 C: A001 NAMESPACE 2886 S: * NAMESPACE (("" "/")) (("Other Users/" "/")) NIL 2887 S: A001 OK NAMESPACE command completed 2889 C: A002 LIST "" "Other Users/%" 2890 S: * LIST () "/" "Other Users/Mike" 2891 S: * LIST () "/" "Other Users/Karen" 2892 S: * LIST () "/" "Other Users/Matthew" 2893 S: * LIST () "/" "Other Users/Tesa" 2894 S: A002 OK LIST command completed 2896 Example 8: 2898 A server that does not support providing a list of other user's 2899 mailboxes that are accessible to the currently logged on user. The 2900 mailboxes are listable if the client includes the name of the other 2901 user with the Other Users' Namespace prefix. 2903 C: A001 NAMESPACE 2904 S: * NAMESPACE (("" "/")) (("#Users/" "/")) NIL 2905 S: A001 OK NAMESPACE command completed 2907 < In this example, the currently logged on user has access to 2908 the Personal Namespace of user Mike, but the server chose to 2909 suppress this information in the LIST response. However, 2910 by appending the user name Mike (received through user input) 2911 to the Other Users' Namespace prefix, the client is able 2912 to get a listing of the personal mailboxes of user Mike. > 2914 C: A002 LIST "" "#Users/%" 2915 S: A002 NO The requested item could not be found. 2917 C: A003 LIST "" "#Users/Mike/%" 2918 S: * LIST () "/" "#Users/Mike/INBOX" 2919 S: * LIST () "/" "#Users/Mike/Foo" 2920 S: A003 OK LIST command completed. 2922 A prefix string might not contain a hierarchy delimiter, because in 2923 some cases it is not needed as part of the prefix. 2925 Example 9: 2927 A server that allows access to the Other Users' Namespace by 2928 prefixing the others' mailboxes with a '~' followed by , 2929 where is a user name as per the LOGIN or AUTHENTICATE 2930 command. 2932 C: A001 NAMESPACE 2933 S: * NAMESPACE (("" "/")) (("~" "/")) NIL 2934 S: A001 OK NAMESPACE command completed 2936 < List the mailboxes for user mark > 2938 C: A002 LIST "" "~mark/%" 2939 S: * LIST () "/" "~mark/INBOX" 2940 S: * LIST () "/" "~mark/foo" 2941 S: A002 OK LIST command completed 2943 6.3.11. STATUS Command 2945 Arguments: mailbox name 2946 status data item names 2948 Responses: REQUIRED untagged responses: STATUS 2950 Result: OK - status completed 2951 NO - status failure: no status for that name 2952 BAD - command unknown or arguments invalid 2954 The STATUS command requests the status of the indicated mailbox. It 2955 does not change the currently selected mailbox, nor does it affect 2956 the state of any messages in the queried mailbox. 2958 The STATUS command provides an alternative to opening a second 2959 IMAP4rev2 connection and doing an EXAMINE command on a mailbox to 2960 query that mailbox's status without deselecting the current mailbox 2961 in the first IMAP4rev2 connection. 2963 Unlike the LIST command, the STATUS command is not guaranteed to be 2964 fast in its response. Under certain circumstances, it can be quite 2965 slow. In some implementations, the server is obliged to open the 2966 mailbox read-only internally to obtain certain status information. 2967 Also unlike the LIST command, the STATUS command does not accept 2968 wildcards. 2970 Note: The STATUS command is intended to access the status of 2971 mailboxes other than the currently selected mailbox. Because the 2972 STATUS command can cause the mailbox to be opened internally, and 2973 because this information is available by other means on the 2974 selected mailbox, the STATUS command SHOULD NOT be used on the 2975 currently selected mailbox. However, servers MUST be able to 2976 execute STATUS command on the selected mailbox. (This might also 2977 implicitly happen when STATUS return option is used in a LIST 2978 command). 2980 The STATUS command MUST NOT be used as a "check for new messages 2981 in the selected mailbox" operation (refer to sections Section 7, 2982 Section 7.3.1 for more information about the proper method for new 2983 message checking). 2985 STATUS SIZE (see below) can take a significant amount of time, 2986 depending upon server implementation. Clients should use STATUS 2987 SIZE cautiously. 2989 The currently defined status data items that can be requested are: 2991 MESSAGES The number of messages in the mailbox. 2993 UIDNEXT The next unique identifier value of the mailbox. Refer to 2994 Section 2.3.1.1 for more information. 2996 UIDVALIDITY The unique identifier validity value of the mailbox. 2997 Refer to Section 2.3.1.1 for more information. 2999 UNSEEN The number of messages which do not have the \Seen flag set. 3001 DELETED The number of messages which have the \Deleted flag set. 3003 SIZE The total size of the mailbox in octets. This is not strictly 3004 required to be an exact value, but it MUST be equal to or greater 3005 than the sum of the values of the RFC822.SIZE FETCH message data 3006 items (see Section 6.4.5) of all messages in the mailbox. 3008 Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES) 3009 S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 3010 S: A042 OK STATUS completed 3012 6.3.12. APPEND Command 3014 Arguments: mailbox name 3015 OPTIONAL flag parenthesized list 3016 OPTIONAL date/time string 3017 message literal 3019 Responses: no specific responses for this command 3021 Result: OK - append completed 3022 NO - append error: can't append to that mailbox, error 3023 in flags or date/time or message text 3024 BAD - command unknown or arguments invalid 3026 The APPEND command appends the literal argument as a new message to 3027 the end of the specified destination mailbox. This argument SHOULD 3028 be in the format of an [RFC-5322] or [I18N-HDRS] message. 8-bit 3029 characters are permitted in the message. A server implementation 3030 that is unable to preserve 8-bit data properly MUST be able to 3031 reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB] 3032 content transfer encoding. 3034 Note: There may be exceptions, e.g., draft messages, in which 3035 required [RFC-5322] header lines are omitted in the message 3036 literal argument to APPEND. The full implications of doing so 3037 must be understood and carefully weighed. 3039 If a flag parenthesized list is specified, the flags SHOULD be set in 3040 the resulting message; otherwise, the flag list of the resulting 3041 message is set to empty by default. 3043 If a date-time is specified, the internal date SHOULD be set in the 3044 resulting message; otherwise, the internal date of the resulting 3045 message is set to the current date and time by default. 3047 If the append is unsuccessful for any reason, the mailbox MUST be 3048 restored to its state before the APPEND attempt (other than possibly 3049 keeping the changed mailbox's UIDNEXT value); no partial appending is 3050 permitted. 3052 If the destination mailbox does not exist, a server MUST return an 3053 error, and MUST NOT automatically create the mailbox. Unless it is 3054 certain that the destination mailbox can not be created, the server 3055 MUST send the response code "[TRYCREATE]" as the prefix of the text 3056 of the tagged NO response. This gives a hint to the client that it 3057 can attempt a CREATE command and retry the APPEND if the CREATE is 3058 successful. 3060 On successful completion of an APPEND, the server SHOULD return an 3061 APPENDUID response code. 3063 In the case of a mailbox that has permissions set so that the client 3064 can APPEND to the mailbox, but not SELECT or EXAMINE it, the server 3065 SHOULD NOT send an APPENDUID response code as it would disclose 3066 information about the mailbox. 3068 In the case of a mailbox that has UIDNOTSTICKY status (see 3069 UIDNOTSTICKY response code definition), the server MAY omit the 3070 APPENDUID response code as it is not meaningful. 3072 If the server does not return the APPENDUID response codes, the 3073 client can discover this information by selecting the destination 3074 mailbox. The location of messages placed in the destination mailbox 3075 by APPEND can be determined by using FETCH and/or SEARCH commands 3076 (e.g., for Message-ID or some unique marker placed in the message in 3077 an APPEND). 3079 If the mailbox is currently selected, the normal new message actions 3080 SHOULD occur. Specifically, the server SHOULD notify the client 3081 immediately via an untagged EXISTS response. If the server does not 3082 do so, the client MAY issue a NOOP command after one or more APPEND 3083 commands. 3085 Example: C: A003 APPEND saved-messages (\Seen) {310} 3086 S: + Ready for literal data 3087 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3088 C: From: Fred Foobar 3089 C: Subject: afternoon meeting 3090 C: To: mooch@owatagu.siam.edu 3091 C: Message-Id: 3092 C: MIME-Version: 1.0 3093 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3094 C: 3095 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3096 C: 3097 S: A003 OK APPEND completed 3099 Example: C: A003 APPEND saved-messages (\Seen) {297} 3100 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3101 C: From: Fred Foobar 3102 C: Subject: afternoon meeting 3103 C: To: mooch@example.com 3104 C: Message-Id: 3105 C: MIME-Version: 1.0 3106 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3107 C: 3108 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3109 C: 3110 S: A003 OK [APPENDUID 38505 3955] APPEND completed 3111 C: A004 COPY 2:4 meeting 3112 S: A004 OK [COPYUID 38505 304,319:320 3956:3958] Done 3113 C: A005 UID COPY 305:310 meeting 3114 S: A005 OK No matching messages, so nothing copied 3115 C: A006 COPY 2 funny 3116 S: A006 OK Done 3117 C: A007 SELECT funny 3118 S: * 1 EXISTS 3119 S: * OK [UIDVALIDITY 3857529045] Validity session-only 3120 S: * OK [UIDNEXT 2] Predicted next UID 3121 S: * NO [UIDNOTSTICKY] Non-persistent UIDs 3122 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 3123 S: * OK [PERMANENTFLAGS (\Deleted \Seen)] Limited 3124 S: A007 OK [READ-WRITE] SELECT completed 3126 In this example, A003 and A004 demonstrate successful appending and 3127 copying to a mailbox that returns the UIDs assigned to the messages. 3128 A005 is an example in which no messages were copied; this is because 3129 in A003, we see that message 2 had UID 304, and message 3 had UID 3130 319; therefore, UIDs 305 through 310 do not exist (refer to 3131 Section 2.3.1.1 for further explanation). A006 is an example of a 3132 message being copied that did not return a COPYUID; and, as expected, 3133 A007 shows that the mail store containing that mailbox does not 3134 support persistent UIDs. 3136 Note: The APPEND command is not used for message delivery, because 3137 it does not provide a mechanism to transfer [SMTP] envelope 3138 information. 3140 6.3.13. IDLE Command 3142 Arguments: none 3144 Responses: continuation data will be requested; the client sends the 3145 continuation data "DONE" to end the command 3147 Result: OK - IDLE completed after client sent "DONE" 3148 NO - failure: the server will not allow the IDLE command 3149 at this time 3150 BAD - command unknown or arguments invalid 3152 Without the IDLE command a client requires to poll the server for 3153 changes to the selected mailbox (new mail, deletions, flag changes). 3154 It's often more desirable to have the server transmit updates to the 3155 client in real time. This allows a user to see new mail immediately. 3156 The IDLE command allows a client to tell the server that it's ready 3157 to accept such real-time updates. 3159 The IDLE command is sent from the client to the server when the 3160 client is ready to accept unsolicited update messages. The server 3161 requests a response to the IDLE command using the continuation ("+") 3162 response. The IDLE command remains active until the client responds 3163 to the continuation, and as long as an IDLE command is active, the 3164 server is now free to send untagged EXISTS, EXPUNGE, FETCH, and other 3165 responses at any time. If the server choose to send unsolicited 3166 FETCH responses, they MUST include UID FETCH item. 3168 The IDLE command is terminated by the receipt of a "DONE" 3169 continuation from the client; such response satisfies the server's 3170 continuation request. At that point, the server MAY send any 3171 remaining queued untagged responses and then MUST immediately send 3172 the tagged response to the IDLE command and prepare to process other 3173 commands. As for other commands, the processing of any new command 3174 may cause the sending of unsolicited untagged responses, subject to 3175 the ambiguity limitations. The client MUST NOT send a command while 3176 the server is waiting for the DONE, since the server will not be able 3177 to distinguish a command from a continuation. 3179 The server MAY consider a client inactive if it has an IDLE command 3180 running, and if such a server has an inactivity timeout it MAY log 3181 the client off implicitly at the end of its timeout period. Because 3182 of that, clients using IDLE are advised to terminate the IDLE and re- 3183 issue it at least every 29 minutes to avoid being logged off. This 3184 still allows a client to receive immediate mailbox updates even 3185 though it need only "poll" at half hour intervals. 3187 Example: C: A001 SELECT INBOX 3188 S: * FLAGS (\Deleted \Seen \Flagged) 3189 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Flagged)] Limited 3190 S: * 3 EXISTS 3191 S: * OK [UIDVALIDITY 1] 3192 S: A001 OK [READ-WRITE] SELECT completed 3193 C: A002 IDLE 3194 S: + idling 3195 ...time passes; new mail arrives... 3196 S: * 4 EXISTS 3197 C: DONE 3198 S: A002 OK IDLE terminated 3199 ...another client expunges message 2 now... 3200 C: A003 FETCH 4 ALL 3201 S: * 4 FETCH (...) 3202 S: A003 OK FETCH completed 3203 C: A004 IDLE 3204 S: * 2 EXPUNGE 3205 S: * 3 EXISTS 3206 S: + idling 3207 ...time passes; another client expunges message 3... 3208 S: * 3 EXPUNGE 3209 S: * 2 EXISTS 3210 ...time passes; new mail arrives... 3211 S: * 3 EXISTS 3212 C: DONE 3213 S: A004 OK IDLE terminated 3214 C: A005 FETCH 3 ALL 3215 S: * 3 FETCH (...) 3216 S: A005 OK FETCH completed 3217 C: A006 IDLE 3219 6.4. Client Commands - Selected State 3221 In the selected state, commands that manipulate messages in a mailbox 3222 are permitted. 3224 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 3225 and the authenticated state commands (SELECT, EXAMINE, NAMESPACE, 3226 CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, STATUS, and 3227 APPEND), the following commands are valid in the selected state: 3228 CLOSE, UNSELECT, EXPUNGE, SEARCH, FETCH, STORE, COPY, MOVE, and UID. 3230 6.4.1. CLOSE Command 3232 Arguments: none 3234 Responses: no specific responses for this command 3235 Result: OK - close completed, now in authenticated state 3236 BAD - command unknown or arguments invalid 3238 The CLOSE command permanently removes all messages that have the 3239 \Deleted flag set from the currently selected mailbox, and returns to 3240 the authenticated state from the selected state. No untagged EXPUNGE 3241 responses are sent. 3243 No messages are removed, and no error is given, if the mailbox is 3244 selected by an EXAMINE command or is otherwise selected read-only. 3246 Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT command 3247 MAY be issued without previously issuing a CLOSE command. The 3248 SELECT, EXAMINE, and LOGOUT commands implicitly close the currently 3249 selected mailbox without doing an expunge. However, when many 3250 messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT sequence is 3251 considerably faster than an EXPUNGE-LOGOUT or EXPUNGE-SELECT because 3252 no untagged EXPUNGE responses (which the client would probably 3253 ignore) are sent. 3255 Example: C: A341 CLOSE 3256 S: A341 OK CLOSE completed 3258 6.4.2. UNSELECT Command 3260 Arguments: none 3262 Responses: no specific responses for this command 3264 Result: OK - unselect completed, now in authenticated state 3265 BAD - no mailbox selected, or argument supplied but none 3266 permitted 3268 The UNSELECT command frees server's resources associated with the 3269 selected mailbox and returns the server to the authenticated state. 3270 This command performs the same actions as CLOSE, except that no 3271 messages are permanently removed from the currently selected mailbox. 3273 Example: C: A342 UNSELECT 3274 S: A342 OK Unselect completed 3276 6.4.3. EXPUNGE Command 3278 Arguments: none 3280 Responses: untagged responses: EXPUNGE 3282 Result: OK - expunge completed 3283 NO - expunge failure: can't expunge (e.g., permission 3284 denied) 3285 BAD - command unknown or arguments invalid 3287 The EXPUNGE command permanently removes all messages that have the 3288 \Deleted flag set from the currently selected mailbox. Before 3289 returning an OK to the client, an untagged EXPUNGE response is sent 3290 for each message that is removed. 3292 Example: C: A202 EXPUNGE 3293 S: * 3 EXPUNGE 3294 S: * 3 EXPUNGE 3295 S: * 5 EXPUNGE 3296 S: * 8 EXPUNGE 3297 S: A202 OK EXPUNGE completed 3299 Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag 3300 set. See the description of the EXPUNGE response for further 3301 explanation. 3303 6.4.4. SEARCH Command 3305 Arguments: OPTIONAL result specifier 3306 OPTIONAL [CHARSET] specification 3307 searching criteria (one or more) 3309 Responses: OPTIONAL untagged response: ESEARCH 3311 Result: OK - search completed 3312 NO - search error: can't search that [CHARSET] or 3313 criteria 3314 BAD - command unknown or arguments invalid 3316 The SEARCH command searches the mailbox for messages that match the 3317 given searching criteria. 3319 The SEARCH command may contain result options. Result options 3320 control what kind of information is returned about messages matching 3321 the search criteria in an untagged ESEARCH response. If no result 3322 option is specified or empty list of options is specified "()", ALL 3323 is assumed (see below). The order of individual options is 3324 arbitrary. Individual options may contain parameters enclosed in 3325 parentheses (*). If an option has parameters, they consist of atoms 3326 and/or strings and/or lists in a specific order. Any options not 3327 defined by extensions that the server supports must be rejected with 3328 a BAD response. 3330 (*) - if an option has a mandatory parameter, which can always be 3331 represented as a number or a sequence-set, the option parameter does 3332 not need the enclosing (). See ABNF for more details. 3334 This document specifies the following result options: 3336 MIN 3338 Return the lowest message number/UID that satisfies the SEARCH 3339 criteria. 3341 If the SEARCH results in no matches, the server MUST NOT 3342 include the MIN result option in the ESEARCH response; however, 3343 it still MUST send the ESEARCH response. 3345 MAX 3347 Return the highest message number/UID that satisfies the SEARCH 3348 criteria. 3350 If the SEARCH results in no matches, the server MUST NOT 3351 include the MAX result option in the ESEARCH response; however, 3352 it still MUST send the ESEARCH response. 3354 ALL 3356 Return all message numbers/UIDs that satisfy the SEARCH 3357 criteria using the sequence-set syntax. Note, the client MUST 3358 NOT assume that messages/UIDs will be listed in any particular 3359 order. 3361 If the SEARCH results in no matches, the server MUST NOT 3362 include the ALL result option in the ESEARCH response; however, 3363 it still MUST send the ESEARCH response. 3365 COUNT Return number of the messages that satisfy the SEARCH 3366 criteria. This result option MUST always be included in the 3367 ESEARCH response. 3369 SAVE 3371 This option tells the server to remember the result of the 3372 SEARCH or UID SEARCH command (as well as any command based on 3373 SEARCH, e.g., SORT and THREAD [RFC5256]>) and store it in an 3374 internal variable that we will reference as the "search result 3375 variable". The client can use the "$" marker to reference the 3376 content of this internal variable. The "$" marker can be used 3377 instead of message sequence or UID sequence in order to 3378 indicate that the server should substitute it with the list of 3379 messages from the search result variable. Thus, the client can 3380 use the result of the latest remembered SEARCH command as a 3381 parameter to another command. See Section 6.4.4.1 for details 3382 on how the value of the search result variable is determined, 3383 how it is affected by other commands executed, and how SAVE 3384 return option interacts with other return options. 3386 In absence of any other SEARCH result option, the SAVE result 3387 option also suppresses any ESEARCH response that would have 3388 been otherwise returned by the SEARCH command. 3390 Note: future extensions to this document can allow servers to return 3391 multiple ESEARCH responses for a single extended SEARCH command. 3392 However all options specified above MUST result in a single ESEARCH 3393 response. These extensions will have to describe how results from 3394 multiple ESEARCH responses are to be amalgamated. 3396 Searching criteria consist of one or more search keys. 3398 When multiple keys are specified, the result is the intersection (AND 3399 function) of all the messages that match those keys. For example, 3400 the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers to all 3401 deleted messages from Smith with INTERNALDATE greater than February 3402 1, 1994. A search key can also be a parenthesized list of one or 3403 more search keys (e.g., for use with the OR and NOT keys). 3405 Server implementations MAY exclude [MIME-IMB] body parts with 3406 terminal content media types other than TEXT and MESSAGE from 3407 consideration in SEARCH matching. 3409 The OPTIONAL [CHARSET] specification consists of the word "CHARSET" 3410 followed by a registered [CHARSET]. It indicates the [CHARSET] of 3411 the strings that appear in the search criteria. [MIME-IMB] content 3412 transfer encodings, and [MIME-HDRS] strings in [RFC-5322]/[MIME-IMB] 3413 headers, MUST be decoded before comparing text. Servers MUST support 3414 US-ASCII and UTF-8 charsets; other [CHARSET]s MAY be supported. 3415 Clients SHOULD use UTF-8. Note that if "CHARSET" is not provided 3416 IMAP4rev2 server MUST assume UTF-8, so selecting CHARSET UTF-8 is 3417 redundant. It is permitted for improved compatibility with existing 3418 IMAP4rev1 clients. 3420 If the server does not support the specified [CHARSET], it MUST 3421 return a tagged NO response (not a BAD). This response SHOULD 3422 contain the BADCHARSET response code, which MAY list the [CHARSET]s 3423 supported by the server. 3425 In all search keys that use strings, a message matches the key if the 3426 string is a substring of the associated text. The matching SHOULD be 3427 case-insensitive for characters within ASCII range. Consider using 3428 [IMAP-I18N] for language-sensitive case-insensitive searching. Note 3429 that the empty string is a substring; this is useful when doing a 3430 HEADER search in order to test for a header field presence in the 3431 message. 3433 The defined search keys are as follows. Refer to the Formal Syntax 3434 section for the precise syntactic definitions of the arguments. 3436 Messages with message sequence numbers corresponding 3437 to the specified message sequence number set. 3439 ALL All messages in the mailbox; the default initial key for ANDing. 3441 ANSWERED Messages with the \Answered flag set. 3443 BCC Messages that contain the specified string in the 3444 envelope structure's BCC field. 3446 BEFORE Messages whose internal date (disregarding time and 3447 timezone) is earlier than the specified date. 3449 BODY Messages that contain the specified string in the body 3450 of the message. Unlike TEXT (see below), this doesn't match any 3451 header fields. 3453 CC Messages that contain the specified string in the 3454 envelope structure's CC field. 3456 DELETED Messages with the \Deleted flag set. 3458 DRAFT Messages with the \Draft flag set. 3460 FLAGGED Messages with the \Flagged flag set. 3462 FROM Messages that contain the specified string in the 3463 envelope structure's FROM field. 3465 HEADER Messages that have a header with the 3466 specified field-name (as defined in [RFC-5322]) and that contains 3467 the specified string in the text of the header (what comes after 3468 the colon). If the string to search is zero-length, this matches 3469 all messages that have a header line with the specified field-name 3470 regardless of the contents. Servers should use substring search 3471 for this SEARCH item, as clients can use it for automatic 3472 processing not initiated by end users. For example this can be 3473 used for searching for Message-ID or Content-Type header field 3474 values that need to be exact, or for searches in header fields 3475 that the IMAP server might not know anything about. 3477 KEYWORD Messages with the specified keyword flag set. 3479 LARGER Messages with an [RFC-5322] size larger than the 3480 specified number of octets. 3482 NOT Messages that do not match the specified search 3483 key. 3485 ON Messages whose internal date (disregarding time and 3486 timezone) is within the specified date. 3488 OR Messages that match either search 3489 key. 3491 SEEN Messages that have the \Seen flag set. 3493 SENTBEFORE Messages whose [RFC-5322] Date: header 3494 (disregarding time and timezone) is earlier than the specified 3495 date. 3497 SENTON Messages whose [RFC-5322] Date: header (disregarding 3498 time and timezone) is within the specified date. 3500 SENTSINCE Messages whose [RFC-5322] Date: header 3501 (disregarding time and timezone) is within or later than the 3502 specified date. 3504 SINCE Messages whose internal date (disregarding time and 3505 timezone) is within or later than the specified date. 3507 SMALLER Messages with an [RFC-5322] size smaller than the 3508 specified number of octets. 3510 SUBJECT Messages that contain the specified string in the 3511 envelope structure's SUBJECT field. 3513 TEXT Messages that contain the specified string in the 3514 header (including MIME header fields) or body of the message. 3516 TO Messages that contain the specified string in the 3517 envelope structure's TO field. 3519 UID Messages with unique identifiers corresponding to 3520 the specified unique identifier set. Sequence set ranges are 3521 permitted. 3523 UNANSWERED Messages that do not have the \Answered flag set. 3525 UNDELETED Messages that do not have the \Deleted flag set. 3527 UNDRAFT Messages that do not have the \Draft flag set. 3529 UNFLAGGED Messages that do not have the \Flagged flag set. 3531 UNKEYWORD Messages that do not have the specified keyword 3532 flag set. 3534 UNSEEN Messages that do not have the \Seen flag set. 3536 Example: C: A282 SEARCH RETURN (MIN COUNT) FLAGGED 3537 SINCE 1-Feb-1994 NOT FROM "Smith" 3538 S: * ESEARCH (TAG "A282") MIN 2 COUNT 3 3539 S: A282 OK SEARCH completed 3541 Example: C: A283 SEARCH RETURN () FLAGGED 3542 SINCE 1-Feb-1994 NOT FROM "Smith" 3543 S: * ESEARCH (TAG "A283") ALL 2,10:11 3544 S: A283 OK SEARCH completed 3546 Example: C: A284 SEARCH TEXT "string not in mailbox" 3547 S: * ESEARCH (TAG "A284") 3548 S: A284 OK SEARCH completed 3549 C: A285 SEARCH CHARSET UTF-8 TEXT {6} 3550 S: + Ready for literal text 3551 C: XXXXXX 3552 S: * ESEARCH (TAG "A285") ALL 43 3553 S: A285 OK SEARCH completed 3555 Note: Since this document is restricted to 7-bit ASCII text, it is 3556 not possible to show actual UTF-8 data. The "XXXXXX" is a 3557 placeholder for what would be 6 octets of 8-bit data in an actual 3558 transaction. 3560 The following example demonstrates finding the first unseen message 3561 in the mailbox: 3563 Example: C: A284 SEARCH RETURN (MIN) UNSEEN 3564 S: * ESEARCH (TAG "A284") MIN 4 3565 S: A284 OK SEARCH completed 3567 The following example demonstrates that if the ESEARCH UID indicator 3568 is present, all data in the ESEARCH response is referring to UIDs; 3569 for example, the MIN result specifier will be followed by a UID. 3571 Example: C: A285 UID SEARCH RETURN (MIN MAX) 1:5000 3572 S: * ESEARCH (TAG "A285") UID MIN 7 MAX 3800 3573 S: A285 OK SEARCH completed 3575 The following example demonstrates returning the number of deleted 3576 messages: 3578 Example: C: A286 SEARCH RETURN (COUNT) DELETED 3579 S: * ESEARCH (TAG "A286") COUNT 15 3580 S: A286 OK SEARCH completed 3582 6.4.4.1. SAVE result option and SEARCH result variable 3584 Upon successful completion of a SELECT or an EXAMINE command (after 3585 the tagged OK response), the current search result variable is reset 3586 to the empty sequence. 3588 A successful SEARCH command with the SAVE result option sets the 3589 value of the search result variable to the list of messages found in 3590 the SEARCH command. For example, if no messages were found, the 3591 search result variable will contain the empty sequence. 3593 Any of the following SEARCH commands MUST NOT change the search 3594 result variable: 3596 a SEARCH command that caused the server to return the BAD tagged 3597 response, 3599 a SEARCH command with no SAVE result option that caused the server 3600 to return NO tagged response, 3602 a successful SEARCH command with no SAVE result option. 3604 A SEARCH command with the SAVE result option that caused the server 3605 to return the NO tagged response sets the value of the search result 3606 variable to the empty sequence. 3608 When a message listed in the search result variable is EXPUNGEd, it 3609 is automatically removed from the list. Implementors are reminded 3610 that if the server stores the list as a list of message numbers, it 3611 MUST automatically adjust them when notifying the client about 3612 expunged messages, as described in Section 7.4.1. 3614 If the server decides to send a new UIDVALIDITY value while the 3615 mailbox is opened, this causes resetting of the search variable to 3616 the empty sequence. 3618 Note that even if the "$" marker contains the empty sequence of 3619 messages, it must be treated by all commands accepting message sets 3620 as parameters as a valid, but non-matching list of messages. For 3621 example, the "FETCH $" command would return a tagged OK response and 3622 no FETCH responses. See also the Example 5 in Section 6.4.4.4. 3624 The SAVE result option doesn't change whether the server would return 3625 items corresponding to MIN, MAX, ALL, or COUNT result options. 3627 When the SAVE result option is combined with the MIN or MAX result 3628 option, and both ALL and COUNT result options are absent, the 3629 corresponding MIN/MAX is returned (if the search result is not 3630 empty), but the "$" marker would contain a single message as returned 3631 in the MIN/MAX return item. 3633 If the SAVE result option is combined with both MIN and MAX result 3634 options, and both ALL and COUNT result options are absent, the "$" 3635 marker would contain zero, one or two messages as returned in the 3636 MIN/MAX return items. 3638 If the SAVE result option is combined with the ALL and/or COUNT 3639 result option(s), the "$" marker would always contain all messages 3640 found by the SEARCH or UID SEARCH command. 3642 The following table summarizes the additional requirement on ESEARCH 3643 server implementations described in this section. 3645 +------------------------------+--------------------+ 3646 | Combination of Result option | "$" marker value | 3647 +------------------------------+--------------------+ 3648 | SAVE MIN | MIN | 3649 | SAVE MAX | MAX | 3650 | SAVE MIN MAX | MIN & MAX | 3651 | SAVE * [m] | all found messages | 3652 +------------------------------+--------------------+ 3654 where '*' means "ALL" and/or "COUNT", and '[m]' means optional "MIN" 3655 and/or "MAX" 3657 Implementation note: server implementors should note that "$" can 3658 reference IMAP message sequences or UID sequences, depending on the 3659 context where it is used. For example, the "$" marker can be set as 3660 a result of a SEARCH (SAVE) command and used as a parameter to a UID 3661 FETCH command (which accepts a UID sequence, not a message sequence), 3662 or the "$" marker can be set as a result of a UID SEARCH (SAVE) 3663 command and used as a parameter to a FETCH command (which accepts a 3664 message sequence, not a UID sequence). Server implementations need 3665 to automatically map the "$" marker value to message numbers or UIDs, 3666 depending on context where the "$" marker is used. 3668 6.4.4.2. Multiple Commands in Progress 3670 Use of a SEARCH RETURN (SAVE) command followed by a command using the 3671 "$" marker creates direct dependency between the two commands. As 3672 directed by Section 5.5, a server MUST execute the two commands in 3673 the order they were received. 3675 A client MAY pipeline a SEARCH RETURN (SAVE) command with one or more 3676 command using the "$" marker, as long as this doesn't create an 3677 ambiguity, as described in by Section 5.5. Examples 7-9 in 3678 Section 6.4.4.4 explain this in more details. 3680 6.4.4.3. Refusing to Save Search Results 3682 In some cases, the server MAY refuse to save a SEARCH (SAVE) result, 3683 for example, if an internal limit on the number of saved results is 3684 reached. In this case, the server MUST return a tagged NO response 3685 containing the NOTSAVED response code and set the search result 3686 variable to the empty sequence, as described in Section 6.4.4.1. 3688 6.4.4.4. Examples showing use of SAVE result option 3690 Only in this section: explanatory comments in examples that start 3691 with // are not part of the protocol. 3693 1) The following example demonstrates how the client can use the 3694 result of a SEARCH command to FETCH headers of interesting messages: 3696 Example 1: 3697 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3698 NOT FROM "Smith" 3699 S: A282 OK SEARCH completed, result saved 3700 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3701 S: * 2 FETCH (UID 14 ... 3702 S: * 84 FETCH (UID 100 ... 3703 S: * 882 FETCH (UID 1115 ... 3704 S: A283 OK completed 3706 The client can also pipeline the two commands: 3708 Example 2: 3709 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3710 NOT FROM "Smith" 3711 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3712 S: A282 OK SEARCH completed 3713 S: * 2 FETCH (UID 14 ... 3714 S: * 84 FETCH (UID 100 ... 3715 S: * 882 FETCH (UID 1115 ... 3716 S: A283 OK completed 3718 2) The following example demonstrates that the result of one SEARCH 3719 command can be used as input to another SEARCH command: 3721 Example 3: 3722 C: A300 SEARCH RETURN (SAVE) SINCE 1-Jan-2004 3723 NOT FROM "Smith" 3724 S: A300 OK SEARCH completed 3725 C: A301 UID SEARCH UID $ SMALLER 4096 3726 S: * ESEARCH (TAG "A301") UID ALL 17,900,901 3727 S: A301 OK completed 3729 Note that the second command in Example 3 can be replaced with: 3730 C: A301 UID SEARCH $ SMALLER 4096 3731 and the result of the command would be the same. 3733 3) The following example shows that the "$" marker can be combined 3734 with other message numbers using the OR SEARCH criterion. 3736 Example 4: 3737 C: P282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3738 NOT FROM "Smith" 3739 S: P282 OK SEARCH completed 3740 C: P283 SEARCH CHARSET UTF-8 (OR $ 1,3000:3021) TEXT {8} 3741 C: YYYYYYYY 3742 S: * ESEARCH (TAG "P283") ALL 882,1102,3003,3005:3006 3743 S: P283 OK completed 3745 Note: Since this document format is restricted to 7-bit ASCII text, 3746 it is not possible to show actual UTF-8 data. The "YYYYYYYY" is a 3747 placeholder for what would be 8 octets of 8-bit data in an actual 3748 transaction. 3750 4) The following example demonstrates that a failed SEARCH sets the 3751 search result variable to the empty list. The server doesn't 3752 implement the KOI8-R charset. 3754 Example 5: 3755 C: B282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3756 NOT FROM "Smith" 3757 S: B282 OK SEARCH completed 3758 C: B283 SEARCH RETURN (SAVE) CHARSET KOI8-R 3759 (OR $ 1,3000:3021) TEXT {4} 3760 C: XXXX 3761 S: B283 NO [BADCHARSET UTF-8] KOI8-R is not supported 3762 //After this command the saved result variable contains 3763 //no messages. A client that wants to reissue the B283 3764 //SEARCH command with another CHARSET would have to reissue 3765 //the B282 command as well. One possible workaround for 3766 //this is to include the desired CHARSET parameter 3767 //in the earliest SEARCH RETURN (SAVE) command in a 3768 //sequence of related SEARCH commands, to cause 3769 //the earliest SEARCH in the sequence to fail. 3770 //A better approach might be to always use CHARSET UTF-8 3771 //instead. 3773 Note: Since this document format is restricted to 7-bit ASCII text, 3774 it is not possible to show actual KOI8-R data. The "XXXX" is a 3775 placeholder for what would be 4 octets of 8-bit data in an actual 3776 transaction. 3778 5) The following example demonstrates that it is not an error to use 3779 the "$" marker when it contains no messages. 3781 Example 6: 3782 C: E282 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3783 NOT FROM "Eric" 3784 C: E283 COPY $ "Other Messages" 3785 //The "$" contains no messages 3786 S: E282 OK SEARCH completed 3787 S: E283 OK COPY completed, nothing copied 3789 Example 7: 3790 C: F282 SEARCH RETURN (SAVE) KEYWORD $Junk 3791 C: F283 COPY $ "Junk" 3792 C: F284 STORE $ +FLAGS.Silent (\Deleted) 3793 S: F282 OK SEARCH completed 3794 S: F283 OK COPY completed 3795 S: F284 OK STORE completed 3797 Example 8: 3798 C: G282 SEARCH RETURN (SAVE) KEYWORD $Junk 3799 C: G283 SEARCH RETURN (ALL) SINCE 28-Oct-2006 3800 FROM "Eric" 3801 // The server can execute the two SEARCH commands 3802 // in any order, as they don't have any dependency. 3803 // For example, it may return: 3804 S: * ESEARCH (TAG "G283") ALL 3:15,27,29:103 3805 S: G283 OK SEARCH completed 3806 S: G282 OK SEARCH completed 3808 The following example demonstrates that the result of the second 3809 SEARCH RETURN (SAVE) always overrides the result of the first. 3811 Example 9: 3812 C: H282 SEARCH RETURN (SAVE) KEYWORD $Junk 3813 C: H283 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3814 FROM "Eric" 3815 S: H282 OK SEARCH completed 3816 S: H283 OK SEARCH completed 3817 // At this point "$" would contain results of H283 3819 The following example demonstrates behavioral difference for 3820 different combinations of ESEARCH result options. 3822 Example 10: 3823 C: C282 SEARCH RETURN (ALL) SINCE 12-Feb-2006 3824 NOT FROM "Smith" 3825 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3826 //$ value hasn't changed 3827 S: C282 OK SEARCH completed 3829 C: C283 SEARCH RETURN (ALL SAVE) SINCE 12-Feb-2006 3830 NOT FROM "Smith" 3831 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3832 //$ value is 2,10:15,21 3833 S: C283 OK SEARCH completed 3835 C: C284 SEARCH RETURN (SAVE MIN) SINCE 12-Feb-2006 3836 NOT FROM "Smith" 3837 S: * ESEARCH (TAG "C284") MIN 2 3838 //$ value is 2 3839 S: C284 OK SEARCH completed 3841 C: C285 SEARCH RETURN (MAX SAVE MIN) SINCE 3842 12-Feb-2006 NOT FROM "Smith" 3843 S: * ESEARCH (TAG "C285") MIN 2 MAX 21 3844 //$ value is 2,21 3845 S: C285 OK SEARCH completed 3847 C: C286 SEARCH RETURN (MAX SAVE MIN COUNT) 3848 SINCE 12-Feb-2006 NOT FROM "Smith" 3849 S: * ESEARCH (TAG "C286") MIN 2 MAX 21 COUNT 8 3850 //$ value is 2,10:15,21 3851 S: C286 OK SEARCH completed 3853 C: C286 SEARCH RETURN (ALL SAVE MIN) SINCE 3854 12-Feb-2006 NOT FROM "Smith" 3855 S: * ESEARCH (TAG "C286") MIN 2 ALL 2,10:15,21 3856 //$ value is 2,10:15,21 3857 S: C286 OK SEARCH completed 3859 6.4.5. FETCH Command 3861 Arguments: sequence set 3862 message data item names or macro 3864 Responses: untagged responses: FETCH 3866 Result: OK - fetch completed 3867 NO - fetch error: can't fetch that data 3868 BAD - command unknown or arguments invalid 3870 The FETCH command retrieves data associated with a message in the 3871 mailbox. The data items to be fetched can be either a single atom or 3872 a parenthesized list. 3874 Most data items, identified in the formal syntax under the msg-att- 3875 static rule, are static and MUST NOT change for any particular 3876 message. Other data items, identified in the formal syntax under the 3877 msg-att-dynamic rule, MAY change, either as a result of a STORE 3878 command or due to external events. 3880 For example, if a client receives an ENVELOPE for a message when 3881 it already knows the envelope, it can safely ignore the newly 3882 transmitted envelope. 3884 There are three macros which specify commonly-used sets of data 3885 items, and can be used instead of data items. A macro must be used 3886 by itself, and not in conjunction with other macros or data items. 3888 ALL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE) 3890 FAST Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE) 3892 FULL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE 3893 BODY) 3895 The currently defined data items that can be fetched are: 3897 BINARY[]<> 3899 Requests that the specified section be transmitted after 3900 performing Content-Transfer-Encoding-related decoding. 3902 The argument, if present, requests that a subset of 3903 the data be returned. The semantics of a partial FETCH BINARY 3904 command are the same as for a partial FETCH BODY command, with 3905 the exception that the arguments refer to the DECODED 3906 section data. 3908 BINARY.PEEK[]<> An alternate form of 3909 BINARY[] that does not implicitly set the \Seen 3910 flag. 3912 BINARY.SIZE[] 3914 Requests the decoded size of the section (i.e., the size to 3915 expect in response to the corresponding FETCH BINARY request). 3917 Note: client authors are cautioned that this might be an 3918 expensive operation for some server implementations. 3919 Needlessly issuing this request could result in degraded 3920 performance due to servers having to calculate the value every 3921 time the request is issued. 3923 BODY Non-extensible form of BODYSTRUCTURE. 3925 BODY[
]<> 3927 The text of a particular body section. The section 3928 specification is a set of zero or more part specifiers 3929 delimited by periods. A part specifier is either a part number 3930 or one of the following: HEADER, HEADER.FIELDS, 3931 HEADER.FIELDS.NOT, MIME, and TEXT. An empty section 3932 specification refers to the entire message, including the 3933 header. 3935 Every message has at least one part number. Non-[MIME-IMB] 3936 messages, and non-multipart [MIME-IMB] messages with no 3937 encapsulated message, only have a part 1. 3939 Multipart messages are assigned consecutive part numbers, as 3940 they occur in the message. If a particular part is of type 3941 message or multipart, its parts MUST be indicated by a period 3942 followed by the part number within that nested multipart part. 3944 A part of type MESSAGE/RFC822 or MESSAGE/GLOBAL also has nested 3945 part numbers, referring to parts of the MESSAGE part's body. 3947 The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part 3948 specifiers can be the sole part specifier or can be prefixed by 3949 one or more numeric part specifiers, provided that the numeric 3950 part specifier refers to a part of type MESSAGE/RFC822 or 3951 MESSAGE/GLOBAL. The MIME part specifier MUST be prefixed by 3952 one or more numeric part specifiers. 3954 The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part 3955 specifiers refer to the [RFC-5322] header of the message or of 3956 an encapsulated [MIME-IMT] MESSAGE/RFC822 or MESSAGE/GLOBAL 3957 message. HEADER.FIELDS and HEADER.FIELDS.NOT are followed by a 3958 list of field-name (as defined in [RFC-5322]) names, and return 3959 a subset of the header. The subset returned by HEADER.FIELDS 3960 contains only those header fields with a field-name that 3961 matches one of the names in the list; similarly, the subset 3962 returned by HEADER.FIELDS.NOT contains only the header fields 3963 with a non-matching field-name. The field-matching is ASCII 3964 range case-insensitive but otherwise exact. Subsetting does 3965 not exclude the [RFC-5322] delimiting blank line between the 3966 header and the body; the blank line is included in all header 3967 fetches, except in the case of a message which has no body and 3968 no blank line. 3970 The MIME part specifier refers to the [MIME-IMB] header for 3971 this part. 3973 The TEXT part specifier refers to the text body of the message, 3974 omitting the [RFC-5322] header. 3976 Here is an example of a complex message with some of its 3977 part specifiers: 3979 HEADER ([RFC-5322] header of the message) 3980 TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 3981 1 TEXT/PLAIN 3982 2 APPLICATION/OCTET-STREAM 3983 3 MESSAGE/RFC822 3984 3.HEADER ([RFC-5322] header of the message) 3985 3.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 3986 3.1 TEXT/PLAIN 3987 3.2 APPLICATION/OCTET-STREAM 3988 4 MULTIPART/MIXED 3989 4.1 IMAGE/GIF 3990 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF) 3991 4.2 MESSAGE/RFC822 3992 4.2.HEADER ([RFC-5322] header of the message) 3993 4.2.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 3994 4.2.1 TEXT/PLAIN 3995 4.2.2 MULTIPART/ALTERNATIVE 3996 4.2.2.1 TEXT/PLAIN 3997 4.2.2.2 TEXT/RICHTEXT 3999 It is possible to fetch a substring of the designated text. 4000 This is done by appending an open angle bracket ("<"), the 4001 octet position of the first desired octet, a period, the 4002 maximum number of octets desired, and a close angle bracket 4003 (">") to the part specifier. If the starting octet is beyond 4004 the end of the text, an empty string is returned. 4006 Any partial fetch that attempts to read beyond the end of the 4007 text is truncated as appropriate. A partial fetch that starts 4008 at octet 0 is returned as a partial fetch, even if this 4009 truncation happened. 4011 Note: This means that BODY[]<0.2048> of a 1500-octet message 4012 will return BODY[]<0> with a literal of size 1500, not 4013 BODY[]. 4015 Note: A substring fetch of a HEADER.FIELDS or 4016 HEADER.FIELDS.NOT part specifier is calculated after 4017 subsetting the header. 4019 The \Seen flag is implicitly set; if this causes the flags to 4020 change, they SHOULD be included as part of the FETCH responses. 4022 BODY.PEEK[
]<> An alternate form of BODY[
] 4023 that does not implicitly set the \Seen flag. 4025 BODYSTRUCTURE The [MIME-IMB] body structure of the message. This is 4026 computed by the server by parsing the [MIME-IMB] header fields in 4027 the [RFC-5322] header and [MIME-IMB] headers. 4029 ENVELOPE The envelope structure of the message. This is computed by 4030 the server by parsing the [RFC-5322] header into the component 4031 parts, defaulting various fields as necessary. 4033 FLAGS The flags that are set for this message. 4035 INTERNALDATE The internal date of the message. 4037 RFC822.SIZE The [RFC-5322] size of the message. 4039 UID The unique identifier for the message. 4041 Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)]) 4042 S: * 2 FETCH .... 4043 S: * 3 FETCH .... 4044 S: * 4 FETCH .... 4045 S: A654 OK FETCH completed 4047 6.4.6. STORE Command 4049 Arguments: sequence set 4050 message data item name 4051 value for message data item 4053 Responses: untagged responses: FETCH 4055 Result: OK - store completed 4056 NO - store error: can't store that data 4057 BAD - command unknown or arguments invalid 4059 The STORE command alters data associated with a message in the 4060 mailbox. Normally, STORE will return the updated value of the data 4061 with an untagged FETCH response. A suffix of ".SILENT" in the data 4062 item name prevents the untagged FETCH, and the server SHOULD assume 4063 that the client has determined the updated value itself or does not 4064 care about the updated value. 4066 Note: Regardless of whether or not the ".SILENT" suffix was used, 4067 the server SHOULD send an untagged FETCH response if a change to a 4068 message's flags from an external source is observed. The intent 4069 is that the status of the flags is determinate without a race 4070 condition. 4072 The currently defined data items that can be stored are: 4074 FLAGS Replace the flags for the message with the 4075 argument. The new value of the flags is returned as if a FETCH of 4076 those flags was done. 4078 FLAGS.SILENT Equivalent to FLAGS, but without returning 4079 a new value. 4081 +FLAGS Add the argument to the flags for the message. 4082 The new value of the flags is returned as if a FETCH of those 4083 flags was done. 4085 +FLAGS.SILENT Equivalent to +FLAGS, but without 4086 returning a new value. 4088 -FLAGS Remove the argument from the flags for the 4089 message. The new value of the flags is returned as if a FETCH of 4090 those flags was done. 4092 -FLAGS.SILENT Equivalent to -FLAGS, but without 4093 returning a new value. 4095 Example: C: A003 STORE 2:4 +FLAGS (\Deleted) 4096 S: * 2 FETCH (FLAGS (\Deleted \Seen)) 4097 S: * 3 FETCH (FLAGS (\Deleted)) 4098 S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen)) 4099 S: A003 OK STORE completed 4101 6.4.7. COPY Command 4103 Arguments: sequence set 4104 mailbox name 4106 Responses: no specific responses for this command 4107 Result: OK - copy completed 4108 NO - copy error: can't copy those messages or to that 4109 name 4110 BAD - command unknown or arguments invalid 4112 The COPY command copies the specified message(s) to the end of the 4113 specified destination mailbox. The flags and internal date of the 4114 message(s) SHOULD be preserved in the copy. 4116 If the destination mailbox does not exist, a server SHOULD return an 4117 error. It SHOULD NOT automatically create the mailbox. Unless it is 4118 certain that the destination mailbox can not be created, the server 4119 MUST send the response code "[TRYCREATE]" as the prefix of the text 4120 of the tagged NO response. This gives a hint to the client that it 4121 can attempt a CREATE command and retry the COPY if the CREATE is 4122 successful. 4124 If the COPY command is unsuccessful for any reason, server 4125 implementations MUST restore the destination mailbox to its state 4126 before the COPY attempt. 4128 On successful completion of a COPY, the server SHOULD return a 4129 COPYUID response code. 4131 In the case of a mailbox that has permissions set so that the client 4132 can COPY to the mailbox, but not SELECT or EXAMINE it, the server 4133 SHOULD NOT send an COPYUID response code as it would disclose 4134 information about the mailbox. 4136 In the case of a mailbox that has UIDNOTSTICKY status (see the 4137 UIDNOTSTICKY response code), the server MAY omit the COPYUID response 4138 code as it is not meaningful. 4140 If the server does not return the COPYUID response code, the client 4141 can discover this information by selecting the destination mailbox. 4142 The location of messages placed in the destination mailbox by COPY 4143 can be determined by using FETCH and/or SEARCH commands (e.g., for 4144 Message-ID). 4146 Example: C: A003 COPY 2:4 MEETING 4147 S: A003 OK COPY completed 4149 6.4.8. MOVE Command 4151 Arguments: sequence set 4152 mailbox name 4154 Responses: no specific responses for this command 4155 Result: OK - move completed 4156 NO - move error: can't move those messages or to that 4157 name 4158 BAD - command unknown or arguments invalid 4160 The MOVE command moves the specified message(s) to the end of the 4161 specified destination mailbox. The flags and internal date of the 4162 message(s) SHOULD be preserved. 4164 This means that a new message is created in the target mailbox with a 4165 new UID, the original message is removed from the source mailbox, and 4166 it appears to the client as a single action. This has the same 4167 effect for each message as this sequence: 4169 1. [UID] COPY 4171 2. [UID] STORE +FLAGS.SILENT \DELETED 4173 3. UID EXPUNGE 4175 Although the effect of the MOVE is the same as the preceding steps, 4176 the semantics are not identical: The intermediate states produced by 4177 those steps do not occur, and the response codes are different. In 4178 particular, though the COPY and EXPUNGE response codes will be 4179 returned, response codes for a STORE MUST NOT be generated and the 4180 \Deleted flag MUST NOT be set for any message. 4182 Because a MOVE applies to a set of messages, it might fail partway 4183 through the set. Regardless of whether the command is successful in 4184 moving the entire set, each individual message SHOULD either be moved 4185 or unaffected. The server MUST leave each message in a state where 4186 it is in at least one of the source or target mailboxes (no message 4187 can be lost or orphaned). The server SHOULD NOT leave any message in 4188 both mailboxes (it would be bad for a partial failure to result in a 4189 bunch of duplicate messages). This is true even if the server 4190 returns a tagged NO response to the command. 4192 Because of the similarity of MOVE to COPY, extensions that affect 4193 COPY affect MOVE in the same way. Response codes such as TRYCREATE 4194 (see Section 7.1), as well as those defined by extensions, are sent 4195 as appropriate. 4197 Servers SHOULD send COPYUID in response to a UID MOVE (see 4198 Section 6.4.9) command. For additional information see Section 7.1. 4200 Servers are also advised to send the COPYUID response code in an 4201 untagged OK before sending EXPUNGE or moved responses. (Sending 4202 COPYUID in the tagged OK, as described in the UIDPLUS specification, 4203 means that clients first receive an EXPUNGE for a message and 4204 afterwards COPYUID for the same message. It can be unnecessarily 4205 difficult to process that sequence usefully.) 4207 An example: 4208 C: a UID MOVE 42:69 foo 4209 S: * OK [COPYUID 432432 42:69 1202:1229] 4210 S: * 22 EXPUNGE 4211 S: (more expunges) 4212 S: a OK Done 4214 Note that the server may send unrelated EXPUNGE responses as well, if 4215 any happen to have been expunged at the same time; this is normal 4216 IMAP operation. 4218 Note that moving a message to the currently selected mailbox (that 4219 is, where the source and target mailboxes are the same) is allowed 4220 when copying the message to the currently selected mailbox is 4221 allowed. 4223 The server may send EXPUNGE responses before the tagged response, so 4224 the client cannot safely send more commands with message sequence 4225 number arguments while the server is processing MOVE. 4227 MOVE and UID MOVE can be pipelined with other commands, but care has 4228 to be taken. Both commands modify sequence numbers and also allow 4229 unrelated EXPUNGE responses. The renumbering of other messages in 4230 the source mailbox following any EXPUNGE response can be surprising 4231 and makes it unsafe to pipeline any command that relies on message 4232 sequence numbers after a MOVE or UID MOVE. Similarly, MOVE cannot be 4233 pipelined with a command that might cause message renumbering. See 4234 Section 5.5, for more information about ambiguities as well as 4235 handling requirements for both clients and servers. 4237 6.4.9. UID Command 4239 Arguments: command name 4240 command arguments 4242 Responses: untagged responses: FETCH, ESEARCH, EXPUNGE 4244 Result: OK - UID command completed 4245 NO - UID command error 4246 BAD - command unknown or arguments invalid 4248 The UID command has three forms. In the first form, it takes as its 4249 arguments a COPY, MOVE, FETCH, or STORE command with arguments 4250 appropriate for the associated command. However, the numbers in the 4251 sequence set argument are unique identifiers instead of message 4252 sequence numbers. Sequence set ranges are permitted, but there is no 4253 guarantee that unique identifiers will be contiguous. 4255 A non-existent unique identifier is ignored without any error message 4256 generated. Thus, it is possible for a UID FETCH command to return an 4257 OK without any data or a UID COPY, UID MOVE or UID STORE to return an 4258 OK without performing any operations. 4260 In the second form, the UID command takes an EXPUNGE command with an 4261 extra parameter the specified a sequence set of UIDs to operate on. 4262 The UID EXPUNGE command permanently removes all messages that both 4263 have the \Deleted flag set and have a UID that is included in the 4264 specified sequence set from the currently selected mailbox. If a 4265 message either does not have the \Deleted flag set or has a UID that 4266 is not included in the specified sequence set, it is not affected. 4268 UID EXPUNGE is particularly useful for disconnected use clients. 4269 By using UID EXPUNGE instead of EXPUNGE when resynchronizing with 4270 the server, the client can ensure that it does not inadvertantly 4271 remove any messages that have been marked as \Deleted by other 4272 clients between the time that the client was last connected and 4273 the time the client resynchronizes. 4275 Example: C: A003 UID EXPUNGE 3000:3002 4276 S: * 3 EXPUNGE 4277 S: * 3 EXPUNGE 4278 S: * 3 EXPUNGE 4279 S: A003 OK UID EXPUNGE completed 4281 In the third form, the UID command takes a SEARCH command with SEARCH 4282 command arguments. The interpretation of the arguments is the same 4283 as with SEARCH; however, the numbers returned in a ESEARCH response 4284 for a UID SEARCH command are unique identifiers instead of message 4285 sequence numbers. Also, the corresponding ESEARCH response MUST 4286 include the UID indicator. For example, the command UID SEARCH 1:100 4287 UID 443:557 returns the unique identifiers corresponding to the 4288 intersection of two sequence sets, the message sequence number range 4289 1:100 and the UID range 443:557. 4291 Note: in the above example, the UID range 443:557 appears. The 4292 same comment about a non-existent unique identifier being ignored 4293 without any error message also applies here. Hence, even if 4294 neither UID 443 or 557 exist, this range is valid and would 4295 include an existing UID 495. 4297 Also note that a UID range of 559:* always includes the UID of the 4298 last message in the mailbox, even if 559 is higher than any 4299 assigned UID value. This is because the contents of a range are 4300 independent of the order of the range endpoints. Thus, any UID 4301 range with * as one of the endpoints indicates at least one 4302 message (the message with the highest numbered UID), unless the 4303 mailbox is empty. 4305 The number after the "*" in an untagged FETCH or EXPUNGE response is 4306 always a message sequence number, not a unique identifier, even for a 4307 UID command response. However, server implementations MUST 4308 implicitly include the UID message data item as part of any FETCH 4309 response caused by a UID command, regardless of whether a UID was 4310 specified as a message data item to the FETCH. 4312 Note: The rule about including the UID message data item as part of a 4313 FETCH response primarily applies to the UID FETCH and UID STORE 4314 commands, including a UID FETCH command that does not include UID as 4315 a message data item. Although it is unlikely that the other UID 4316 commands will cause an untagged FETCH, this rule applies to these 4317 commands as well. 4319 Example: C: A999 UID FETCH 4827313:4828442 FLAGS 4320 S: * 23 FETCH (FLAGS (\Seen) UID 4827313) 4321 S: * 24 FETCH (FLAGS (\Seen) UID 4827943) 4322 S: * 25 FETCH (FLAGS (\Seen) UID 4828442) 4323 S: A999 OK UID FETCH completed 4325 6.5. Client Commands - Experimental/Expansion 4327 6.5.1. X Command 4329 Arguments: implementation defined 4331 Responses: implementation defined 4333 Result: OK - command completed 4334 NO - failure 4335 BAD - command unknown or arguments invalid 4337 Any command prefixed with an X is an experimental command. Commands 4338 which are not part of this specification, a standard or standards- 4339 track revision of this specification, or an IESG-approved 4340 experimental protocol, MUST use the X prefix. 4342 Any added untagged responses issued by an experimental command MUST 4343 also be prefixed with an X. Server implementations MUST NOT send any 4344 such untagged responses, unless the client requested it by issuing 4345 the associated experimental command. 4347 Example: C: a441 CAPABILITY 4348 S: * CAPABILITY IMAP4rev2 XPIG-LATIN 4349 S: a441 OK CAPABILITY completed 4350 C: A442 XPIG-LATIN 4351 S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay 4352 S: A442 OK XPIG-LATIN ompleted-cay 4354 7. Server Responses 4356 Server responses are in three forms: status responses, server data, 4357 and command continuation request. The information contained in a 4358 server response, identified by "Contents:" in the response 4359 descriptions below, is described by function, not by syntax. The 4360 precise syntax of server responses is described in the Formal Syntax 4361 section. 4363 The client MUST be prepared to accept any response at all times. 4365 Status responses can be tagged or untagged. Tagged status responses 4366 indicate the completion result (OK, NO, or BAD status) of a client 4367 command, and have a tag matching the command. 4369 Some status responses, and all server data, are untagged. An 4370 untagged response is indicated by the token "*" instead of a tag. 4371 Untagged status responses indicate server greeting, or server status 4372 that does not indicate the completion of a command (for example, an 4373 impending system shutdown alert). For historical reasons, untagged 4374 server data responses are also called "unsolicited data", although 4375 strictly speaking, only unilateral server data is truly 4376 "unsolicited". 4378 Certain server data MUST be recorded by the client when it is 4379 received; this is noted in the description of that data. Such data 4380 conveys critical information which affects the interpretation of all 4381 subsequent commands and responses (e.g., updates reflecting the 4382 creation or destruction of messages). 4384 Other server data SHOULD be recorded for later reference; if the 4385 client does not need to record the data, or if recording the data has 4386 no obvious purpose (e.g., a SEARCH response when no SEARCH command is 4387 in progress), the data SHOULD be ignored. 4389 An example of unilateral untagged server data occurs when the IMAP 4390 connection is in the selected state. In the selected state, the 4391 server checks the mailbox for new messages as part of command 4392 execution. Normally, this is part of the execution of every command; 4393 hence, a NOOP command suffices to check for new messages. If new 4394 messages are found, the server sends untagged EXISTS response 4395 reflecting the new size of the mailbox. Server implementations that 4396 offer multiple simultaneous access to the same mailbox SHOULD also 4397 send appropriate unilateral untagged FETCH and EXPUNGE responses if 4398 another agent changes the state of any message flags or expunges any 4399 messages. 4401 Command continuation request responses use the token "+" instead of a 4402 tag. These responses are sent by the server to indicate acceptance 4403 of an incomplete client command and readiness for the remainder of 4404 the command. 4406 7.1. Server Responses - Status Responses 4408 Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD 4409 can be tagged or untagged. PREAUTH and BYE are always untagged. 4411 Status responses MAY include an OPTIONAL "response code". A response 4412 code consists of data inside square brackets in the form of an atom, 4413 possibly followed by a space and arguments. The response code 4414 contains additional information or status codes for client software 4415 beyond the OK/NO/BAD condition, and are defined when there is a 4416 specific action that a client can take based upon the additional 4417 information. 4419 The currently defined response codes are: 4421 ALERT 4423 The human-readable text contains a special alert that MUST be 4424 presented to the user in a fashion that calls the user's 4425 attention to the message. 4427 ALREADYEXISTS 4429 The operation attempts to create something that already exists, 4430 such as when the CREATE or RENAME directories attempt to create 4431 a mailbox and there is already one of that name. 4433 C: o356 RENAME this that 4434 S: o356 NO [ALREADYEXISTS] Mailbox "that" already exists 4436 APPENDUID 4438 Followed by the UIDVALIDITY of the destination mailbox and the 4439 UID assigned to the appended message in the destination 4440 mailbox, indicates that the message has been appended to the 4441 destination mailbox with that UID. 4443 If the server also supports the [MULTIAPPEND] extension, and if 4444 multiple messages were appended in the APPEND command, then the 4445 second value is a UID set containing the UIDs assigned to the 4446 appended messages, in the order they were transmitted in the 4447 APPEND command. This UID set may not contain extraneous UIDs 4448 or the symbol "*". 4450 Note: the UID set form of the APPENDUID response code MUST 4451 NOT be used if only a single message was appended. In 4452 particular, a server MUST NOT send a range such as 123:123. 4453 This is because a client that does not support [MULTIAPPEND] 4454 expects only a single UID and not a UID set. 4456 UIDs are assigned in strictly ascending order in the mailbox 4457 (refer to Section 2.3.1.1); note that a range of 12:10 is 4458 exactly equivalent to 10:12 and refers to the sequence 4459 10,11,12. 4461 This response code is returned in a tagged OK response to the 4462 APPEND command. 4464 AUTHENTICATIONFAILED 4466 Authentication failed for some reason on which the server is 4467 unwilling to elaborate. Typically, this includes "unknown 4468 user" and "bad password". 4470 This is the same as not sending any response code, except that 4471 when a client sees AUTHENTICATIONFAILED, it knows that the 4472 problem wasn't, e.g., UNAVAILABLE, so there's no point in 4473 trying the same login/password again later. 4475 C: b LOGIN "fred" "foo" 4476 S: b NO [AUTHENTICATIONFAILED] Authentication failed 4478 AUTHORIZATIONFAILED 4480 Authentication succeeded in using the authentication identity, 4481 but the server cannot or will not allow the authentication 4482 identity to act as the requested authorization identity. This 4483 is only applicable when the authentication and authorization 4484 identities are different. 4486 C: c1 AUTHENTICATE PLAIN 4487 [...] 4488 S: c1 NO [AUTHORIZATIONFAILED] No such authorization-ID 4489 C: c2 AUTHENTICATE PLAIN 4490 [...] 4491 S: c2 NO [AUTHORIZATIONFAILED] Authenticator is not an admin 4493 BADCHARSET 4495 Optionally followed by a parenthesized list of charsets. A 4496 SEARCH failed because the given charset is not supported by 4497 this implementation. If the optional list of charsets is 4498 given, this lists the charsets that are supported by this 4499 implementation. 4501 CANNOT 4503 The operation violates some invariant of the server and can 4504 never succeed. 4506 C: l create "///////" 4507 S: l NO [CANNOT] Adjacent slashes are not supported 4509 CAPABILITY 4511 Followed by a list of capabilities. This can appear in the 4512 initial OK or PREAUTH response to transmit an initial 4513 capabilities list. It can also appear in tagged responses to 4514 LOGIN or AUTHENTICATE commands. This makes it unnecessary for 4515 a client to send a separate CAPABILITY command if it recognizes 4516 this response. 4518 CLIENTBUG 4520 The server has detected a client bug. This can accompany all 4521 of OK, NO, and BAD, depending on what the client bug is. 4523 C: k1 select "/archive/projects/experiment-iv" 4524 [...] 4525 S: k1 OK [READ-ONLY] Done 4526 C: k2 status "/archive/projects/experiment-iv" (messages) 4527 [...] 4528 S: k2 OK [CLIENTBUG] Done 4530 CLOSED 4532 The CLOSED response code has no parameters. A server return 4533 the CLOSED response code when the currently selected mailbox is 4534 closed implicitly using the SELECT/EXAMINE command on another 4535 mailbox. The CLOSED response code serves as a boundary between 4536 responses for the previously opened mailbox (which was closed) 4537 and the newly selected mailbox; all responses before the CLOSED 4538 response code relate to the mailbox that was closed, and all 4539 subsequent responses relate to the newly opened mailbox. 4541 There is no need to return the CLOSED response code on 4542 completion of the CLOSE or the UNSELECT command (or similar), 4543 whose purpose is to close the currently selected mailbox 4544 without opening a new one. 4546 The server MAY also return an unsolicited CLOSED response code 4547 when it wants to force the client to return to authenticated 4548 state. For example, the server can do that when the mailbox 4549 requires repairs or is deleted in another session. 4551 CONTACTADMIN 4553 The user should contact the system administrator or support 4554 desk. 4556 C: e login "fred" "foo" 4557 S: e OK [CONTACTADMIN] 4559 COPYUID 4561 Followed by the UIDVALIDITY of the destination mailbox, a UID 4562 set containing the UIDs of the message(s) in the source mailbox 4563 that were copied to the destination mailbox and containing the 4564 UIDs assigned to the copied message(s) in the destination 4565 mailbox, indicates that the message(s) have been copied to the 4566 destination mailbox with the stated UID(s). 4568 The source UID set is in the order the message(s) were copied; 4569 the destination UID set corresponds to the source UID set and 4570 is in the same order. Neither of the UID sets may contain 4571 extraneous UIDs or the symbol "*". 4573 UIDs are assigned in strictly ascending order in the mailbox 4574 (refer to Section 2.3.1.1); note that a range of 12:10 is 4575 exactly equivalent to 10:12 and refers to the sequence 4576 10,11,12. 4578 This response code is returned in a tagged OK response to the 4579 COPY command. 4581 CORRUPTION 4583 The server discovered that some relevant data (e.g., the 4584 mailbox) are corrupt. This response code does not include any 4585 information about what's corrupt, but the server can write that 4586 to its logfiles. 4588 C: i select "/archive/projects/experiment-iv" 4589 S: i NO [CORRUPTION] Cannot open mailbox 4591 EXPIRED 4593 Either authentication succeeded or the server no longer had the 4594 necessary data; either way, access is no longer permitted using 4595 that passphrase. The client or user should get a new 4596 passphrase. 4598 C: d login "fred" "foo" 4599 S: d NO [EXPIRED] That password isn't valid any more 4601 EXPUNGEISSUED 4603 Someone else has issued an EXPUNGE for the same mailbox. The 4604 client may want to issue NOOP soon. [IMAP-MULTIACCESS] 4605 discusses this subject in depth. 4607 C: h search from fred@example.com 4608 S: * ESEARCH (TAG "h") ALL 1:3,5,8,13,21,42 4609 S: h OK [EXPUNGEISSUED] Search completed 4611 INUSE 4613 An operation has not been carried out because it involves 4614 sawing off a branch someone else is sitting on. Someone else 4615 may be holding an exclusive lock needed for this operation, or 4616 the operation may involve deleting a resource someone else is 4617 using, typically a mailbox. 4619 The operation may succeed if the client tries again later. 4621 C: g delete "/archive/projects/experiment-iv" 4622 S: g NO [INUSE] Mailbox in use 4624 LIMIT 4626 The operation ran up against an implementation limit of some 4627 kind, such as the number of flags on a single message or the 4628 number of flags used in a mailbox. 4630 C: m STORE 42 FLAGS f1 f2 f3 f4 f5 ... f250 4631 S: m NO [LIMIT] At most 32 flags in one mailbox supported 4633 NONEXISTENT 4635 The operation attempts to delete something that does not exist. 4636 Similar to ALREADYEXISTS. 4638 C: p RENAME this that 4639 S: p NO [NONEXISTENT] No such mailbox 4641 NOPERM 4643 The access control system (e.g., Access Control List (ACL), see 4644 [RFC4314] does not permit this user to carry out an operation, 4645 such as selecting or creating a mailbox. 4647 C: f select "/archive/projects/experiment-iv" 4648 S: f NO [NOPERM] Access denied 4650 OVERQUOTA 4652 The user would be over quota after the operation. (The user 4653 may or may not be over quota already.) 4655 Note that if the server sends OVERQUOTA but doesn't support the 4656 IMAP QUOTA extension defined by [RFC2087], then there is a 4657 quota, but the client cannot find out what the quota is. 4659 C: n1 uid copy 1:* oldmail 4660 S: n1 NO [OVERQUOTA] Sorry 4662 C: n2 uid copy 1:* oldmail 4663 S: n2 OK [OVERQUOTA] You are now over your soft quota 4665 PARSE 4667 The human-readable text represents an error in parsing the 4668 [RFC-5322] header or [MIME-IMB] headers of a message in the 4669 mailbox. 4671 PERMANENTFLAGS 4673 Followed by a parenthesized list of flags, indicates which of 4674 the known flags the client can change permanently. Any flags 4675 that are in the FLAGS untagged response, but not the 4676 PERMANENTFLAGS list, can not be set permanently. The 4677 PERMANENTFLAGS list can also include the special flag \*, which 4678 indicates that it is possible to create new keywords by 4679 attempting to store those keywords in the mailbox. If the 4680 client attempts to STORE a flag that is not in the 4681 PERMANENTFLAGS list, the server will either ignore the change 4682 or store the state change for the remainder of the current 4683 session only. 4685 There is no need for a server that included the special flag \* 4686 to return a new PERMANENTFLAGS response code when a new keyword 4687 was successfully set on a message upon client request. However 4688 if the server has a limit on the number of different keywords 4689 that can be stored in a mailbox and that limit is reached, the 4690 server MUST send a new PERMANENTFLAGS response code without the 4691 special flag \*. 4693 PRIVACYREQUIRED 4695 The operation is not permitted due to a lack of privacy. If 4696 Transport Layer Security (TLS) is not in use, the client could 4697 try STARTTLS (see Section 6.2.1) and then repeat the operation. 4699 C: d login "fred" "foo" 4700 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4702 C: d select inbox 4703 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4705 READ-ONLY 4707 The mailbox is selected read-only, or its access while selected 4708 has changed from read-write to read-only. 4710 READ-WRITE 4712 The mailbox is selected read-write, or its access while 4713 selected has changed from read-only to read-write. 4715 SERVERBUG 4717 The server encountered a bug in itself or violated one of its 4718 own invariants. 4720 C: j select "/archive/projects/experiment-iv" 4721 S: j NO [SERVERBUG] This should not happen 4723 TRYCREATE 4725 An APPEND or COPY attempt is failing because the target mailbox 4726 does not exist (as opposed to some other reason). This is a 4727 hint to the client that the operation can succeed if the 4728 mailbox is first created by the CREATE command. 4730 UIDNEXT 4732 Followed by a decimal number, indicates the next unique 4733 identifier value. Refer to Section 2.3.1.1 for more 4734 information. 4736 UIDNOTSTICKY 4738 The selected mailbox is supported by a mail store that does not 4739 support persistent UIDs; that is, UIDVALIDITY will be different 4740 each time the mailbox is selected. Consequently, APPEND or 4741 COPY to this mailbox will not return an APPENDUID or COPYUID 4742 response code. 4744 This response code is returned in an untagged NO response to 4745 the SELECT command. 4747 Note: servers SHOULD NOT have any UIDNOTSTICKY mail stores. 4748 This facility exists to support legacy mail stores in which 4749 it is technically infeasible to support persistent UIDs. 4750 This should be avoided when designing new mail stores. 4752 UIDVALIDITY 4754 Followed by a decimal number, indicates the unique identifier 4755 validity value. Refer to Section 2.3.1.1 for more information. 4757 UNAVAILABLE 4759 Temporary failure because a subsystem is down. For example, an 4760 IMAP server that uses a Lightweight Directory Access Protocol 4761 (LDAP) or Radius server for authentication might use this 4762 response code when the LDAP/Radius server is down. 4764 C: a LOGIN "fred" "foo" 4765 S: a NO [UNAVAILABLE] User's backend down for maintenance 4767 UNKNOWN-CTE 4769 The server does not know how to decode the section's Content- 4770 Transfer-Encoding. 4772 Additional response codes defined by particular client or server 4773 implementations SHOULD be prefixed with an "X" until they are added 4774 to a revision of this protocol. Client implementations SHOULD ignore 4775 response codes that they do not recognize. 4777 7.1.1. OK Response 4779 Contents: OPTIONAL response code 4780 human-readable text 4782 The OK response indicates an information message from the server. 4783 When tagged, it indicates successful completion of the associated 4784 command. The human-readable text MAY be presented to the user as an 4785 information message. The untagged form indicates an information-only 4786 message; the nature of the information MAY be indicated by a response 4787 code. 4789 The untagged form is also used as one of three possible greetings at 4790 connection startup. It indicates that the connection is not yet 4791 authenticated and that a LOGIN or an AUTHENTICATE command is needed. 4793 Example: S: * OK IMAP4rev2 server ready 4794 C: A001 LOGIN fred blurdybloop 4795 S: * OK [ALERT] System shutdown in 10 minutes 4796 S: A001 OK LOGIN Completed 4798 7.1.2. NO Response 4800 Contents: OPTIONAL response code 4801 human-readable text 4803 The NO response indicates an operational error message from the 4804 server. When tagged, it indicates unsuccessful completion of the 4805 associated command. The untagged form indicates a warning; the 4806 command can still complete successfully. The human-readable text 4807 describes the condition. 4809 Example: C: A222 COPY 1:2 owatagusiam 4810 S: * NO Disk is 98% full, please delete unnecessary data 4811 S: A222 OK COPY completed 4812 C: A223 COPY 3:200 blurdybloop 4813 S: * NO Disk is 98% full, please delete unnecessary data 4814 S: * NO Disk is 99% full, please delete unnecessary data 4815 S: A223 NO COPY failed: disk is full 4817 7.1.3. BAD Response 4819 Contents: OPTIONAL response code 4820 human-readable text 4822 The BAD response indicates an error message from the server. When 4823 tagged, it reports a protocol-level error in the client's command; 4824 the tag indicates the command that caused the error. The untagged 4825 form indicates a protocol-level error for which the associated 4826 command can not be determined; it can also indicate an internal 4827 server failure. The human-readable text describes the condition. 4829 Example: C: ...very long command line... 4830 S: * BAD Command line too long 4831 C: ...empty line... 4832 S: * BAD Empty command line 4833 C: A443 EXPUNGE 4834 S: * BAD Disk crash, attempting salvage to a new disk! 4835 S: * OK Salvage successful, no data lost 4836 S: A443 OK Expunge completed 4838 7.1.4. PREAUTH Response 4840 Contents: OPTIONAL response code 4841 human-readable text 4843 The PREAUTH response is always untagged, and is one of three possible 4844 greetings at connection startup. It indicates that the connection 4845 has already been authenticated by external means; thus no LOGIN/ 4846 AUTHENTICATE command is needed. 4848 Example: S: * PREAUTH IMAP4rev2 server logged in as Smith 4850 7.1.5. BYE Response 4852 Contents: OPTIONAL response code 4853 human-readable text 4855 The BYE response is always untagged, and indicates that the server is 4856 about to close the connection. The human-readable text MAY be 4857 displayed to the user in a status report by the client. The BYE 4858 response is sent under one of four conditions: 4860 1. as part of a normal logout sequence. The server will close the 4861 connection after sending the tagged OK response to the LOGOUT 4862 command. 4864 2. as a panic shutdown announcement. The server closes the 4865 connection immediately. 4867 3. as an announcement of an inactivity autologout. The server 4868 closes the connection immediately. 4870 4. as one of three possible greetings at connection startup, 4871 indicating that the server is not willing to accept a connection 4872 from this client. The server closes the connection immediately. 4874 The difference between a BYE that occurs as part of a normal LOGOUT 4875 sequence (the first case) and a BYE that occurs because of a failure 4876 (the other three cases) is that the connection closes immediately in 4877 the failure case. In all cases the client SHOULD continue to read 4878 response data from the server until the connection is closed; this 4879 will ensure that any pending untagged or completion responses are 4880 read and processed. 4882 Example: S: * BYE Autologout; idle for too long 4884 7.2. Server Responses - Server and Mailbox Status 4886 These responses are always untagged. This is how server and mailbox 4887 status data are transmitted from the server to the client. Many of 4888 these responses typically result from a command with the same name. 4890 7.2.1. The ENABLED Response 4892 Contents: capability listing 4894 The ENABLED response occurs as a result of an ENABLE command. The 4895 capability listing contains a space-separated listing of capability 4896 names that the server supports and that were successfully enabled. 4897 The ENABLED response may contain no capabilities, which means that no 4898 extensions listed by the client were successfully enabled. 4900 7.2.2. CAPABILITY Response 4902 Contents: capability listing 4904 The CAPABILITY response occurs as a result of a CAPABILITY command. 4905 The capability listing contains a space-separated listing of 4906 capability names that the server supports. The capability listing 4907 MUST include the atom "IMAP4rev2". 4909 In addition, client and server implementations MUST implement the 4910 STARTTLS, LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) 4911 capabilities. See the Security Considerations section for important 4912 information. 4914 A capability name which begins with "AUTH=" indicates that the server 4915 supports that particular authentication mechanism. 4917 The LOGINDISABLED capability indicates that the LOGIN command is 4918 disabled, and that the server will respond with a tagged NO response 4919 to any attempt to use the LOGIN command even if the user name and 4920 password are valid. An IMAP client MUST NOT issue the LOGIN command 4921 if the server advertises the LOGINDISABLED capability. 4923 Other capability names indicate that the server supports an 4924 extension, revision, or amendment to the IMAP4rev2 protocol. Server 4925 responses MUST conform to this document until the client issues a 4926 command that uses the associated capability. 4928 Capability names MUST either begin with "X" or be standard or 4929 standards-track IMAP4rev2 extensions, revisions, or amendments 4930 registered with IANA. A server MUST NOT offer unregistered or non- 4931 standard capability names, unless such names are prefixed with an 4932 "X". 4934 Client implementations SHOULD NOT require any capability name other 4935 than "IMAP4rev2", and MUST ignore any unknown capability names. 4937 A server MAY send capabilities automatically, by using the CAPABILITY 4938 response code in the initial PREAUTH or OK responses, and by sending 4939 an updated CAPABILITY response code in the tagged OK response as part 4940 of a successful authentication. It is unnecessary for a client to 4941 send a separate CAPABILITY command if it recognizes these automatic 4942 capabilities. 4944 Example: S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI XPIG-LATIN 4946 7.2.3. LIST Response 4948 Contents: name attributes 4949 hierarchy delimiter 4950 name 4951 OPTIONAL extension data 4953 The LIST response occurs as a result of a LIST command. It returns a 4954 single name that matches the LIST specification. There can be 4955 multiple LIST responses for a single LIST command. 4957 The following base name attributes are defined: 4959 \NonExistent The "\NonExistent" attribute indicates that a mailbox 4960 name does not refer to an existing mailbox. Note that this 4961 attribute is not meaningful by itself, as mailbox names that match 4962 the canonical LIST pattern but don't exist must not be returned 4963 unless one of the two conditions listed below is also satisfied: 4965 1. The mailbox name also satisfies the selection criteria (for 4966 example, it is subscribed and the "SUBSCRIBED" selection 4967 option has been specified). 4969 2. "RECURSIVEMATCH" has been specified, and the mailbox name has 4970 at least one descendant mailbox name that does not match the 4971 LIST pattern and does match the selection criteria. 4973 In practice, this means that the "\NonExistent" attribute is 4974 usually returned with one or more of "\Subscribed", "\Remote", 4975 "\HasChildren", or the CHILDINFO extended data item. 4977 The "\NonExistent" attribute implies "\NoSelect". 4979 \Noinferiors It is not possible for any child levels of hierarchy to 4980 exist under this name; no child levels exist now and none can be 4981 created in the future. 4983 \Noselect It is not possible to use this name as a selectable 4984 mailbox. 4986 \HasChildren The presence of this attribute indicates that the 4987 mailbox has child mailboxes. A server SHOULD NOT set this 4988 attribute if there are child mailboxes and the user does not have 4989 permission to access any of them. In this case, \HasNoChildren 4990 SHOULD be used. In many cases, however, a server may not be able 4991 to efficiently compute whether a user has access to any child 4992 mailbox. Note that even though the \HasChildren attribute for a 4993 mailbox must be correct at the time of processing of the mailbox, 4994 a client must be prepared to deal with a situation when a mailbox 4995 is marked with the \HasChildren attribute, but no child mailbox 4996 appears in the response to the LIST command. This might happen, 4997 for example, due to children mailboxes being deleted or made 4998 inaccessible to the user (using access control) by another client 4999 before the server is able to list them. 5001 \HasNoChildren The presence of this attribute indicates that the 5002 mailbox has NO child mailboxes that are accessible to the 5003 currently authenticated user. 5005 \Marked The mailbox has been marked "interesting" by the server; the 5006 mailbox probably contains messages that have been added since the 5007 last time the mailbox was selected. 5009 \Unmarked The mailbox does not contain any additional messages since 5010 the last time the mailbox was selected. 5012 \Subscribed The mailbox name was subscribed to using the SUBSCRIBE 5013 command. 5015 \Remote The mailbox is a remote mailbox. 5017 It is an error for the server to return both a \HasChildren and a 5018 \HasNoChildren attribute in the same LIST response. 5020 Note: the \HasNoChildren attribute should not be confused with the 5021 \NoInferiors attribute, which indicates that no child mailboxes 5022 exist now and none can be created in the future. 5024 If it is not feasible for the server to determine whether or not the 5025 mailbox is "interesting", the server SHOULD NOT send either \Marked 5026 or \Unmarked. The server MUST NOT send more than one of \Marked, 5027 \Unmarked, and \Noselect for a single mailbox, and MAY send none of 5028 these. 5030 In addition to the base name attributes defined above, an IMAP server 5031 MAY also include any or all of the following attributes that denote 5032 "role" (or "special-use") of a mailbox. These attributes are 5033 included along with base attributes defined above. A given mailbox 5034 may have none, one, or more than one of these attributes. In some 5035 cases, a special use is advice to a client about what to put in that 5036 mailbox. In other cases, it's advice to a client about what to 5037 expect to find there. 5039 \All This mailbox presents all messages in the user's message store. 5040 Implementations MAY omit some messages, such as, perhaps, those in 5041 \Trash and \Junk. When this special use is supported, it is 5042 almost certain to represent a virtual mailbox. 5044 \Archive This mailbox is used to archive messages. The meaning of 5045 an "archival" mailbox is server-dependent; typically, it will be 5046 used to get messages out of the inbox, or otherwise keep them out 5047 of the user's way, while still making them accessible. 5049 \Drafts This mailbox is used to hold draft messages -- typically, 5050 messages that are being composed but have not yet been sent. In 5051 some server implementations, this might be a virtual mailbox, 5052 containing messages from other mailboxes that are marked with the 5053 "\Draft" message flag. Alternatively, this might just be advice 5054 that a client put drafts here. 5056 \Flagged This mailbox presents all messages marked in some way as 5057 "important". When this special use is supported, it is likely to 5058 represent a virtual mailbox collecting messages (from other 5059 mailboxes) that are marked with the "\Flagged" message flag. 5061 \Junk This mailbox is where messages deemed to be junk mail are 5062 held. Some server implementations might put messages here 5063 automatically. Alternatively, this might just be advice to a 5064 client-side spam filter. 5066 \Sent This mailbox is used to hold copies of messages that have been 5067 sent. Some server implementations might put messages here 5068 automatically. Alternatively, this might just be advice that a 5069 client save sent messages here. 5071 \Trash This mailbox is used to hold messages that have been deleted 5072 or marked for deletion. In some server implementations, this 5073 might be a virtual mailbox, containing messages from other 5074 mailboxes that are marked with the "\Deleted" message flag. 5075 Alternatively, this might just be advice that a client that 5076 chooses not to use the IMAP "\Deleted" model should use this as 5077 its trash location. In server implementations that strictly 5078 expect the IMAP "\Deleted" model, this special use is likely not 5079 to be supported. 5081 All of special-use attributes are OPTIONAL, and any given server or 5082 message store may support any combination of the attributes, or none 5083 at all. In most cases, there will likely be at most one mailbox with 5084 a given attribute for a given user, but in some server or message 5085 store implementations it might be possible for multiple mailboxes to 5086 have the same special-use attribute. 5088 Special-use attributes are likely to be user-specific. User Adam 5089 might share his \Sent mailbox with user Barb, but that mailbox is 5090 unlikely to also serve as Barb's \Sent mailbox. 5092 The hierarchy delimiter is a character used to delimit levels of 5093 hierarchy in a mailbox name. A client can use it to create child 5094 mailboxes, and to search higher or lower levels of naming hierarchy. 5095 All children of a top-level hierarchy node MUST use the same 5096 separator character. A NIL hierarchy delimiter means that no 5097 hierarchy exists; the name is a "flat" name. 5099 The name represents an unambiguous left-to-right hierarchy, and MUST 5100 be valid for use as a reference in LIST command. Unless \Noselect or 5101 \NonExistent is indicated, the name MUST also be valid as an argument 5102 for commands, such as SELECT, that accept mailbox names. 5104 The name might be followed by an OPTIONAL series of extended fields, 5105 a parenthesized list of tagged data (also referred to as "extended 5106 data item"). The first element of an extended field is a tag, which 5107 identifies the type of data. The server MAY return data in the 5108 extended fields that was not directly solicited by the client in the 5109 corresponding LIST command. For example, the client can enable extra 5110 extended fields by using another IMAP extension that make use of the 5111 extended LIST responses. The client MUST ignore all extended fields 5112 it doesn't recognize. 5114 Example: S: * LIST (\Noselect) "/" ~/Mail/foo 5116 Example: S: * LIST (\Marked) ":" Tables (tablecloth (("edge" "lacy") 5117 ("color" "red")) Sample "text") 5118 S: * LIST () ":" Tables:new (tablecloth ("edge" "lacy") 5119 Sample ("text" "more text")) 5121 7.2.4. NAMESPACE Response 5123 Contents: the prefix and hierarchy delimiter to the server's 5124 Personal Namespace(s), Other Users' Namespace(s), and 5125 Shared Namespace(s) 5127 The NAMESPACE response occurs as a result of a NAMESPACE command. It 5128 contains the prefix and hierarchy delimiter to the server's Personal 5129 Namespace(s), Other Users' Namespace(s), and Shared Namespace(s) that 5130 the server wishes to expose. The response will contain a NIL for any 5131 namespace class that is not available. Namespace-Response-Extensions 5132 ABNF non terminal is defined for extensibility and MAY be included in 5133 the response. 5135 Example: S: * NAMESPACE (("" "/")) (("~" "/")) NIL 5137 7.2.5. STATUS Response 5139 Contents: name 5140 status parenthesized list 5142 The STATUS response occurs as a result of an STATUS command. It 5143 returns the mailbox name that matches the STATUS specification and 5144 the requested mailbox status information. 5146 Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 5148 7.2.6. ESEARCH Response 5150 Contents: one or more search-return-data pairs 5152 The ESEARCH response occurs as a result of a SEARCH or UID SEARCH 5153 command. 5155 The ESEARCH response starts with an optional search correlator. If 5156 it is missing, then the response was not caused by a particular IMAP 5157 command, whereas if it is present, it contains the tag of the command 5158 that caused the response to be returned. 5160 The search correlator is followed by an optional UID indicator. If 5161 this indicator is present, all data in the ESEARCH response refers to 5162 UIDs, otherwise all returned data refers to message numbers. 5164 The rest of the ESEARCH response contains one or more search data 5165 pairs. Each pair starts with unique return item name, followed by a 5166 space and the corresponding data. Search data pairs may be returned 5167 in any order. Unless specified otherwise by an extension, any return 5168 item name SHOULD appear only once in an ESEARCH response. 5170 [[TBD: describe the most common search data pairs returned.]] 5172 Example: S: * ESEARCH UID COUNT 5 ALL 4:19,21,28 5174 Example: S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28 5176 Example: S: * ESEARCH COUNT 5 ALL 1:17,21 5178 7.2.7. FLAGS Response 5180 Contents: flag parenthesized list 5182 The FLAGS response occurs as a result of a SELECT or EXAMINE command. 5183 The flag parenthesized list identifies the flags (at a minimum, the 5184 system-defined flags) that are applicable for this mailbox. Flags 5185 other than the system flags can also exist, depending on server 5186 implementation. 5188 The update from the FLAGS response MUST be recorded by the client. 5190 Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5192 7.3. Server Responses - Mailbox Size 5194 These responses are always untagged. This is how changes in the size 5195 of the mailbox are transmitted from the server to the client. 5196 Immediately following the "*" token is a number that represents a 5197 message count. 5199 7.3.1. EXISTS Response 5201 Contents: none 5203 The EXISTS response reports the number of messages in the mailbox. 5204 This response occurs as a result of a SELECT or EXAMINE command, and 5205 if the size of the mailbox changes (e.g., new messages). 5207 The update from the EXISTS response MUST be recorded by the client. 5209 Example: S: * 23 EXISTS 5211 7.4. Server Responses - Message Status 5213 These responses are always untagged. This is how message data are 5214 transmitted from the server to the client, often as a result of a 5215 command with the same name. Immediately following the "*" token is a 5216 number that represents a message sequence number. 5218 7.4.1. EXPUNGE Response 5220 Contents: none 5222 The EXPUNGE response reports that the specified message sequence 5223 number has been permanently removed from the mailbox. The message 5224 sequence number for each successive message in the mailbox is 5225 immediately decremented by 1, and this decrement is reflected in 5226 message sequence numbers in subsequent responses (including other 5227 untagged EXPUNGE responses). 5229 The EXPUNGE response also decrements the number of messages in the 5230 mailbox; it is not necessary to send an EXISTS response with the new 5231 value. 5233 As a result of the immediate decrement rule, message sequence numbers 5234 that appear in a set of successive EXPUNGE responses depend upon 5235 whether the messages are removed starting from lower numbers to 5236 higher numbers, or from higher numbers to lower numbers. For 5237 example, if the last 5 messages in a 9-message mailbox are expunged, 5238 a "lower to higher" server will send five untagged EXPUNGE responses 5239 for message sequence number 5, whereas a "higher to lower server" 5240 will send successive untagged EXPUNGE responses for message sequence 5241 numbers 9, 8, 7, 6, and 5. 5243 An EXPUNGE response MUST NOT be sent when no command is in progress, 5244 nor while responding to a FETCH, STORE, or SEARCH command. This rule 5245 is necessary to prevent a loss of synchronization of message sequence 5246 numbers between client and server. A command is not "in progress" 5247 until the complete command has been received; in particular, a 5248 command is not "in progress" during the negotiation of command 5249 continuation. 5251 Note: UID FETCH, UID STORE, and UID SEARCH are different commands 5252 from FETCH, STORE, and SEARCH. An EXPUNGE response MAY be sent 5253 during a UID command. 5255 The update from the EXPUNGE response MUST be recorded by the client. 5257 Example: S: * 44 EXPUNGE 5259 7.4.2. FETCH Response 5261 Contents: message data 5263 The FETCH response returns data about a message to the client. The 5264 data are pairs of data item names and their values in parentheses. 5265 This response occurs as the result of a FETCH or STORE command, as 5266 well as by unilateral server decision (e.g., flag updates). 5268 The current data items are: 5270 BINARY[]<> 5272 An or expressing the content of the 5273 specified section after removing any Content-Transfer-Encoding- 5274 related encoding. If is present it refers to the 5275 offset within the DECODED section data. 5277 If the domain of the decoded data is "8bit" and the data does 5278 not contain the NUL octet, the server SHOULD return the data in 5279 a instead of a ; this allows the client to 5280 determine if the "8bit" data contains the NUL octet without 5281 having to explicitly scan the data stream for for NULs. 5283 Messaging clients and servers have been notoriously lax in 5284 their adherence to the Internet CRLF convention for terminating 5285 lines of textual data (text/* media types) in Internet 5286 protocols. When sending data in BINARY[...] FETCH data item, 5287 servers MUST ensure that textual line-oriented sections are 5288 always transmitted using the IMAP4 CRLF line termination 5289 syntax, regardless of the underlying storage representation of 5290 the data on the server. 5292 If the server does not know how to decode the section's 5293 Content-Transfer-Encoding, it MUST fail the request and issue a 5294 "NO" response that contains the "UNKNOWN-CTE" response code. 5296 BINARY.SIZE[] 5298 The size of the section after removing any Content-Transfer- 5299 Encoding-related encoding. The value returned MUST match the 5300 size of the or that will be returned by 5301 the corresponding FETCH BINARY request. 5303 If the server does not know how to decode the section's 5304 Content-Transfer-Encoding, it MUST fail the request and issue a 5305 "NO" response that contains the "UNKNOWN-CTE" response code. 5307 BODY A form of BODYSTRUCTURE without extension data. 5309 BODY[
]<> 5311 A string expressing the body contents of the specified section. 5312 The string SHOULD be interpreted by the client according to the 5313 content transfer encoding, body type, and subtype. 5315 If the origin octet is specified, this string is a substring of 5316 the entire body contents, starting at that origin octet. This 5317 means that BODY[]<0> MAY be truncated, but BODY[] is NEVER 5318 truncated. 5320 Note: The origin octet facility MUST NOT be used by a server 5321 in a FETCH response unless the client specifically requested 5322 it by means of a FETCH of a BODY[
]<> data 5323 item. 5325 8-bit textual data is permitted if a [CHARSET] identifier is 5326 part of the body parameter parenthesized list for this section. 5327 Note that headers (part specifiers HEADER or MIME, or the 5328 header portion of a MESSAGE/RFC822 or MESSAGE/GLOBAL part), MAY 5329 be in UTF-8. Note also that the [RFC-5322] delimiting blank 5330 line between the header and the body is not affected by header 5331 line subsetting; the blank line is always included as part of 5332 header data, except in the case of a message which has no body 5333 and no blank line. 5335 Non-textual data such as binary data MUST be transfer encoded 5336 into a textual form, such as BASE64, prior to being sent to the 5337 client. To derive the original binary data, the client MUST 5338 decode the transfer encoded string. 5340 BODYSTRUCTURE 5342 A parenthesized list that describes the [MIME-IMB] body 5343 structure of a message. This is computed by the server by 5344 parsing the [MIME-IMB] header fields, defaulting various fields 5345 as necessary. 5347 For example, a simple text message of 48 lines and 2279 octets 5348 can have a body structure of: ("TEXT" "PLAIN" ("CHARSET" "US- 5349 ASCII") NIL NIL "7BIT" 2279 48) 5351 Multiple parts are indicated by parenthesis nesting. Instead 5352 of a body type as the first element of the parenthesized list, 5353 there is a sequence of one or more nested body structures. The 5354 second element of the parenthesized list is the multipart 5355 subtype (mixed, digest, parallel, alternative, etc.). 5357 For example, a two part message consisting of a text and a 5358 BASE64-encoded text attachment can have a body structure of: 5359 (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 5360 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") 5361 "<960723163407.20117h@cac.washington.edu>" "Compiler diff" 5362 "BASE64" 4554 73) "MIXED") 5364 Extension data follows the multipart subtype. Extension data 5365 is never returned with the BODY fetch, but can be returned with 5366 a BODYSTRUCTURE fetch. Extension data, if present, MUST be in 5367 the defined order. The extension data of a multipart body part 5368 are in the following order: 5370 body parameter parenthesized list A parenthesized list of 5371 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5372 "bar" is the value of "foo", and "rag" is the value of 5373 "baz"] as defined in [MIME-IMB]. Servers SHOULD decode 5374 parameter value continuations as described in [RFC2231], for 5375 example, if the message contains parameters "foo*0*" and 5376 "foo*1*", the server should RFC2231-decode them, concatenate 5377 and return the resulting value as "foo*". 5379 body disposition A parenthesized list, consisting of a 5380 disposition type string, followed by a parenthesized list of 5381 disposition attribute/value pairs as defined in 5383 [DISPOSITION]. Servers SHOULD decode parameter value 5384 continuations as described in [RFC2231]. 5386 body language A string or parenthesized list giving the body 5387 language value as defined in [LANGUAGE-TAGS]. 5389 body location A string giving the body content URI as defined 5390 in [LOCATION]. 5392 Any following extension data are not yet defined in this 5393 version of the protocol. Such extension data can consist of 5394 zero or more NILs, strings, numbers, or potentially nested 5395 parenthesized lists of such data. Client implementations that 5396 do a BODYSTRUCTURE fetch MUST be prepared to accept such 5397 extension data. Server implementations MUST NOT send such 5398 extension data until it has been defined by a revision of this 5399 protocol. 5401 The basic fields of a non-multipart body part are in the 5402 following order: 5404 body type A string giving the content media type name as 5405 defined in [MIME-IMB]. 5407 body subtype A string giving the content subtype name as 5408 defined in [MIME-IMB]. 5410 body parameter parenthesized list A parenthesized list of 5411 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5412 "bar" is the value of "foo" and "rag" is the value of "baz"] 5413 as defined in [MIME-IMB]. 5415 body id A string giving the Content-ID header field value as 5416 defined in Section 7 of [MIME-IMB]. 5418 body description A string giving the Content-Description 5419 header field value as defined in Section 8 of [MIME-IMB]. 5421 body encoding A string giving the content transfer encoding as 5422 defined in Section 6 of [MIME-IMB]. 5424 body size A number giving the size of the body in octets. 5425 Note that this size is the size in its transfer encoding and 5426 not the resulting size after any decoding. 5428 A body type of type MESSAGE and subtype RFC822 contains, 5429 immediately after the basic fields, the envelope structure, 5430 body structure, and size in text lines of the encapsulated 5431 message. 5433 A body type of type TEXT contains, immediately after the basic 5434 fields, the size of the body in text lines. Note that this 5435 size is the size in its content transfer encoding and not the 5436 resulting size after any decoding. 5438 Extension data follows the basic fields and the type-specific 5439 fields listed above. Extension data is never returned with the 5440 BODY fetch, but can be returned with a BODYSTRUCTURE fetch. 5441 Extension data, if present, MUST be in the defined order. 5443 The extension data of a non-multipart body part are in the 5444 following order: 5446 body MD5 A string giving the body MD5 value as defined in 5447 [MD5]. 5449 body disposition A parenthesized list with the same content 5450 and function as the body disposition for a multipart body 5451 part. 5453 body language A string or parenthesized list giving the body 5454 language value as defined in [LANGUAGE-TAGS]. 5456 body location A string giving the body content URI as defined 5457 in [LOCATION]. 5459 Any following extension data are not yet defined in this 5460 version of the protocol, and would be as described above under 5461 multipart extension data. 5463 ENVELOPE 5465 A parenthesized list that describes the envelope structure of a 5466 message. This is computed by the server by parsing the 5467 [RFC-5322] header into the component parts, defaulting various 5468 fields as necessary. 5470 The fields of the envelope structure are in the following 5471 order: date, subject, from, sender, reply-to, to, cc, bcc, in- 5472 reply-to, and message-id. The date, subject, in-reply-to, and 5473 message-id fields are strings. The from, sender, reply-to, to, 5474 cc, and bcc fields are parenthesized lists of address 5475 structures. 5477 An address structure is a parenthesized list that describes an 5478 electronic mail address. The fields of an address structure 5479 are in the following order: personal name, [SMTP] at-domain- 5480 list (source route, obs-route), mailbox name, and host name. 5482 [RFC-5322] group syntax is indicated by a special form of 5483 address structure in which the host name field is NIL. If the 5484 mailbox name field is also NIL, this is an end of group marker 5485 (semi-colon in RFC 822 syntax). If the mailbox name field is 5486 non-NIL, this is a start of group marker, and the mailbox name 5487 field holds the group name phrase. 5489 If the Date, Subject, In-Reply-To, and Message-ID header lines 5490 are absent in the [RFC-5322] header, the corresponding member 5491 of the envelope is NIL; if these header lines are present but 5492 empty the corresponding member of the envelope is the empty 5493 string. 5495 Note: some servers may return a NIL envelope member in the 5496 "present but empty" case. Clients SHOULD treat NIL and 5497 empty string as identical. 5499 Note: [RFC-5322] requires that all messages have a valid 5500 Date header. Therefore, the date member in the envelope can 5501 not be NIL or the empty string. 5503 Note: [RFC-5322] requires that the In-Reply-To and Message- 5504 ID headers, if present, have non-empty content. Therefore, 5505 the in-reply-to and message-id members in the envelope can 5506 not be the empty string. 5508 If the From, To, Cc, and Bcc header lines are absent in the 5509 [RFC-5322] header, or are present but empty, the corresponding 5510 member of the envelope is NIL. 5512 If the Sender or Reply-To lines are absent in the [RFC-5322] 5513 header, or are present but empty, the server sets the 5514 corresponding member of the envelope to be the same value as 5515 the from member (the client is not expected to know to do 5516 this). 5518 Note: [RFC-5322] requires that all messages have a valid 5519 From header. Therefore, the from, sender, and reply-to 5520 members in the envelope can not be NIL. 5522 FLAGS A parenthesized list of flags that are set for this message. 5524 INTERNALDATE A string representing the internal date of the message. 5526 RFC822.SIZE A number expressing the [RFC-5322] size of the message. 5528 UID A number expressing the unique identifier of the message. 5530 Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827) 5532 7.5. Server Responses - Command Continuation Request 5534 The command continuation request response is indicated by a "+" token 5535 instead of a tag. This form of response indicates that the server is 5536 ready to accept the continuation of a command from the client. The 5537 remainder of this response is a line of text. 5539 This response is used in the AUTHENTICATE command to transmit server 5540 data to the client, and request additional client data. This 5541 response is also used if an argument to any command is a 5542 synchronizing literal. 5544 The client is not permitted to send the octets of the synchronizing 5545 literal unless the server indicates that it is expected. This 5546 permits the server to process commands and reject errors on a line- 5547 by-line basis. The remainder of the command, including the CRLF that 5548 terminates a command, follows the octets of the literal. If there 5549 are any additional command arguments, the literal octets are followed 5550 by a space and those arguments. 5552 Example: C: A001 LOGIN {11} 5553 S: + Ready for additional command text 5554 C: FRED FOOBAR {7} 5555 S: + Ready for additional command text 5556 C: fat man 5557 S: A001 OK LOGIN completed 5558 C: A044 BLURDYBLOOP {102856} 5559 S: A044 BAD No such command as "BLURDYBLOOP" 5561 8. Sample IMAP4rev2 connection 5563 The following is a transcript of an IMAP4rev2 connection. A long 5564 line in this sample is broken for editorial clarity. 5566 S: * OK IMAP4rev2 Service Ready 5567 C: a001 login mrc secret 5568 S: a001 OK LOGIN completed 5569 C: a002 select inbox 5570 S: * 18 EXISTS 5571 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5572 S: * OK [UIDVALIDITY 3857529045] UIDs valid 5573 S: a002 OK [READ-WRITE] SELECT completed 5574 C: a003 fetch 12 full 5575 S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700" 5576 RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)" 5577 "IMAP4rev2 WG mtg summary and minutes" 5578 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5579 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5580 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5581 ((NIL NIL "imap" "cac.washington.edu")) 5582 ((NIL NIL "minutes" "CNRI.Reston.VA.US") 5583 ("John Klensin" NIL "KLENSIN" "MIT.EDU")) NIL NIL 5584 "") 5585 BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 5586 92)) 5587 S: a003 OK FETCH completed 5588 C: a004 fetch 12 body[header] 5589 S: * 12 FETCH (BODY[HEADER] {342} 5590 S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT) 5591 S: From: Terry Gray 5592 S: Subject: IMAP4rev2 WG mtg summary and minutes 5593 S: To: imap@cac.washington.edu 5594 S: cc: minutes@CNRI.Reston.VA.US, John Klensin 5595 S: Message-Id: 5596 S: MIME-Version: 1.0 5597 S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 5598 S: 5599 S: ) 5600 S: a004 OK FETCH completed 5601 C: a005 store 12 +flags \deleted 5602 S: * 12 FETCH (FLAGS (\Seen \Deleted)) 5603 S: a005 OK +FLAGS completed 5604 C: a006 logout 5605 S: * BYE IMAP4rev2 server terminating connection 5606 S: a006 OK LOGOUT completed 5608 9. Formal Syntax 5610 The following syntax specification uses the Augmented Backus-Naur 5611 Form (ABNF) notation as specified in [ABNF]. 5613 In the case of alternative or optional rules in which a later rule 5614 overlaps an earlier rule, the rule which is listed earlier MUST take 5615 priority. For example, "\Seen" when parsed as a flag is the \Seen 5616 flag name and not a flag-extension, even though "\Seen" can be parsed 5617 as a flag-extension. Some, but not all, instances of this rule are 5618 noted below. 5620 Note: [ABNF] rules MUST be followed strictly; in particular: 5622 (1) Except as noted otherwise, all alphabetic characters are case- 5623 insensitive. The use of upper or lower case characters to define 5624 token strings is for editorial clarity only. Implementations MUST 5625 accept these strings in a case-insensitive fashion. 5627 (2) In all cases, SP refers to exactly one space. It is NOT 5628 permitted to substitute TAB, insert additional spaces, or 5629 otherwise treat SP as being equivalent to LWSP. 5631 (3) The ASCII NUL character, %x00, MUST NOT be used at any time. 5633 address = "(" addr-name SP addr-adl SP addr-mailbox SP 5634 addr-host ")" 5636 addr-adl = nstring 5637 ; Holds route from [RFC-5322] obs-route if 5638 ; non-NIL 5640 addr-host = nstring 5641 ; NIL indicates [RFC-5322] group syntax. 5642 ; Otherwise, holds [RFC-5322] domain name 5644 addr-mailbox = nstring 5645 ; NIL indicates end of [RFC-5322] group; if 5646 ; non-NIL and addr-host is NIL, holds 5647 ; [RFC-5322] group name. 5648 ; Otherwise, holds [RFC-5322] local-part 5649 ; after removing [RFC-5322] quoting 5651 addr-name = nstring 5652 ; If non-NIL, holds phrase from [RFC-5322] 5653 ; mailbox after removing [RFC-5322] quoting 5655 append = "APPEND" SP mailbox [SP flag-list] [SP date-time] SP 5656 literal 5658 append-uid = uniqueid 5660 astring = 1*ASTRING-CHAR / string 5661 ASTRING-CHAR = ATOM-CHAR / resp-specials 5663 atom = 1*ATOM-CHAR 5665 ATOM-CHAR = 5667 atom-specials = "(" / ")" / "{" / SP / CTL / list-wildcards / 5668 quoted-specials / resp-specials 5670 authenticate = "AUTHENTICATE" SP auth-type [SP initial-resp] 5671 *(CRLF base64) 5673 auth-type = atom 5674 ; Defined by [SASL] 5676 base64 = *(4base64-char) [base64-terminal] 5678 base64-char = ALPHA / DIGIT / "+" / "/" 5679 ; Case-sensitive 5681 base64-terminal = (2base64-char "==") / (3base64-char "=") 5683 body = "(" (body-type-1part / body-type-mpart) ")" 5685 body-extension = nstring / number / 5686 "(" body-extension *(SP body-extension) ")" 5687 ; Future expansion. Client implementations 5688 ; MUST accept body-extension fields. Server 5689 ; implementations MUST NOT generate 5690 ; body-extension fields except as defined by 5691 ; future standard or standards-track 5692 ; revisions of this specification. 5694 body-ext-1part = body-fld-md5 [SP body-fld-dsp [SP body-fld-lang 5695 [SP body-fld-loc *(SP body-extension)]]] 5696 ; MUST NOT be returned on non-extensible 5697 ; "BODY" fetch 5699 body-ext-mpart = body-fld-param [SP body-fld-dsp [SP body-fld-lang 5700 [SP body-fld-loc *(SP body-extension)]]] 5701 ; MUST NOT be returned on non-extensible 5702 ; "BODY" fetch 5704 body-fields = body-fld-param SP body-fld-id SP body-fld-desc SP 5705 body-fld-enc SP body-fld-octets 5707 body-fld-desc = nstring 5708 body-fld-dsp = "(" string SP body-fld-param ")" / nil 5710 body-fld-enc = (DQUOTE ("7BIT" / "8BIT" / "BINARY" / "BASE64"/ 5711 "QUOTED-PRINTABLE") DQUOTE) / string 5713 body-fld-id = nstring 5715 body-fld-lang = nstring / "(" string *(SP string) ")" 5717 body-fld-loc = nstring 5719 body-fld-lines = number 5721 body-fld-md5 = nstring 5723 body-fld-octets = number 5725 body-fld-param = "(" string SP string *(SP string SP string) ")" / nil 5727 body-type-1part = (body-type-basic / body-type-msg / body-type-text) 5728 [SP body-ext-1part] 5730 body-type-basic = media-basic SP body-fields 5731 ; MESSAGE subtype MUST NOT be "RFC822" or "GLOBAL" 5733 body-type-mpart = 1*body SP media-subtype 5734 [SP body-ext-mpart] 5735 ; MULTIPART body part 5737 body-type-msg = media-message SP body-fields SP envelope 5738 SP body SP body-fld-lines 5740 body-type-text = media-text SP body-fields SP body-fld-lines 5742 capability = ("AUTH=" auth-type) / atom 5743 ; New capabilities MUST begin with "X" or be 5744 ; registered with IANA as standard or 5745 ; standards-track 5747 capability-data = "CAPABILITY" *(SP capability) SP "IMAP4rev2" 5748 *(SP capability) 5749 ; Servers MUST implement the STARTTLS, AUTH=PLAIN, 5750 ; and LOGINDISABLED capabilities 5751 ; Servers which offer RFC 1730 compatibility MUST 5752 ; list "IMAP4" as the first capability. 5754 CHAR8 = %x01-ff 5755 ; any OCTET except NUL, %x00 5757 charset = atom / quoted 5759 childinfo-extended-item = "CHILDINFO" SP "(" 5760 list-select-base-opt-quoted 5761 *(SP list-select-base-opt-quoted) ")" 5762 ; Extended data item (mbox-list-extended-item) 5763 ; returned when the RECURSIVEMATCH 5764 ; selection option is specified. 5765 ; Note 1: the CHILDINFO tag can be returned 5766 ; with and without surrounding quotes, as per 5767 ; mbox-list-extended-item-tag production. 5768 ; Note 2: The selection options are always returned 5769 ; quoted, unlike their specification in 5770 ; the extended LIST command. 5772 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 5773 ; attributes for CHILDREN return option, at most one 5774 ; possible per LIST response 5776 command = tag SP (command-any / command-auth / command-nonauth / 5777 command-select) CRLF 5778 ; Modal based on state 5780 command-any = "CAPABILITY" / "LOGOUT" / "NOOP" / enable / x-command 5781 ; Valid in all states 5783 command-auth = append / create / delete / examine / list / 5784 Namespace-Command / 5785 rename / select / status / subscribe / unsubscribe / 5786 idle 5787 ; Valid only in Authenticated or Selected state 5789 command-nonauth = login / authenticate / "STARTTLS" 5790 ; Valid only when in Not Authenticated state 5792 command-select = "CLOSE" / "UNSELECT" / "EXPUNGE" / copy / 5793 move / fetch / store / search / uid 5794 ; Valid only when in Selected state 5796 continue-req = "+" SP (resp-text / base64) CRLF 5798 copy = "COPY" SP sequence-set SP mailbox 5800 create = "CREATE" SP mailbox 5801 ; Use of INBOX gives a NO error 5803 date = date-text / DQUOTE date-text DQUOTE 5804 date-day = 1*2DIGIT 5805 ; Day of month 5807 date-day-fixed = (SP DIGIT) / 2DIGIT 5808 ; Fixed-format version of date-day 5810 date-month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / 5811 "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" 5813 date-text = date-day "-" date-month "-" date-year 5815 date-year = 4DIGIT 5817 date-time = DQUOTE date-day-fixed "-" date-month "-" date-year 5818 SP time SP zone DQUOTE 5820 delete = "DELETE" SP mailbox 5821 ; Use of INBOX gives a NO error 5823 digit-nz = %x31-39 5824 ; 1-9 5826 eitem-standard-tag = atom 5827 ; a tag for extended list data defined in a Standard 5828 ; Track or Experimental RFC. 5830 eitem-vendor-tag = vendor-token "-" atom 5831 ; a vendor-specific tag for extended list data 5833 enable = "ENABLE" 1*(SP capability) 5835 enable-data = "ENABLED" *(SP capability) 5837 envelope = "(" env-date SP env-subject SP env-from SP 5838 env-sender SP env-reply-to SP env-to SP env-cc SP 5839 env-bcc SP env-in-reply-to SP env-message-id ")" 5841 env-bcc = "(" 1*address ")" / nil 5843 env-cc = "(" 1*address ")" / nil 5845 env-date = nstring 5847 env-from = "(" 1*address ")" / nil 5849 env-in-reply-to = nstring 5851 env-message-id = nstring 5852 env-reply-to = "(" 1*address ")" / nil 5854 env-sender = "(" 1*address ")" / nil 5856 env-subject = nstring 5858 env-to = "(" 1*address ")" / nil 5860 esearch-response = "ESEARCH" [search-correlator] [SP "UID"] 5861 *(SP search-return-data) 5862 ; ESEARCH response replaces SEARCH response 5863 ; from IMAP4rev1. 5865 examine = "EXAMINE" SP mailbox 5867 fetch = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" / 5868 fetch-att / "(" fetch-att *(SP fetch-att) ")") 5870 fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" / 5871 "RFC822.SIZE" / 5872 "BODY" ["STRUCTURE"] / "UID" / 5873 "BODY" section [partial] / 5874 "BODY.PEEK" section [partial] / 5875 "BINARY" [".PEEK"] section-binary [partial] / 5876 "BINARY.SIZE" section-binary 5878 flag = "\Answered" / "\Flagged" / "\Deleted" / 5879 "\Seen" / "\Draft" / flag-keyword / flag-extension 5880 ; Does not include "\Recent" 5882 flag-extension = "\" atom 5883 ; Future expansion. Client implementations 5884 ; MUST accept flag-extension flags. Server 5885 ; implementations MUST NOT generate 5886 ; flag-extension flags except as defined by 5887 ; future standard or standards-track 5888 ; revisions of this specification. 5889 ; "\Recent" was defined in RFC 3501 5890 ; and is now deprecated. 5892 flag-fetch = flag 5894 flag-keyword = "$MDNSent" / "$Forwarded" / atom 5896 flag-list = "(" [flag *(SP flag)] ")" 5898 flag-perm = flag / "\*" 5899 greeting = "*" SP (resp-cond-auth / resp-cond-bye) CRLF 5901 header-fld-name = astring 5903 header-list = "(" header-fld-name *(SP header-fld-name) ")" 5905 idle = "IDLE" CRLF "DONE" 5907 initial-resp = (base64 / "=") 5908 ; "initial response" defined in 5909 ; Section 5.1 of [RFC4422] 5911 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 5912 [SP list-return-opts] 5914 list-mailbox = 1*list-char / string 5916 list-char = ATOM-CHAR / list-wildcards / resp-specials 5918 list-return-opts = "RETURN" SP 5919 "(" [return-option *(SP return-option)] ")" 5920 ; list return options, e.g., CHILDREN 5922 list-select-base-opt = "SUBSCRIBED" / option-extension 5923 ; options that can be used by themselves 5925 list-select-base-opt-quoted = DQUOTE list-select-base-opt DQUOTE 5927 list-select-independent-opt = "REMOTE" / option-extension 5928 ; options that do not syntactically interact with 5929 ; other options 5931 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 5932 ; options that require a list-select-base-opt 5933 ; to also be present 5935 list-select-opt = list-select-base-opt / list-select-independent-opt 5936 / list-select-mod-opt 5937 ; An option registration template is described in 5938 ; Section 9.3 of this document. 5940 list-select-opts = "(" [ 5941 (*(list-select-opt SP) list-select-base-opt 5942 *(SP list-select-opt)) 5943 / (list-select-independent-opt 5944 *(SP list-select-independent-opt)) 5945 ] ")" 5947 ; Any number of options may be in any order. 5948 ; If a list-select-mod-opt appears, then a 5949 ; list-select-base-opt must also appear. 5950 ; This allows these: 5951 ; () 5952 ; (REMOTE) 5953 ; (SUBSCRIBED) 5954 ; (SUBSCRIBED REMOTE) 5955 ; (SUBSCRIBED RECURSIVEMATCH) 5956 ; (SUBSCRIBED REMOTE RECURSIVEMATCH) 5957 ; But does NOT allow these: 5958 ; (RECURSIVEMATCH) 5959 ; (REMOTE RECURSIVEMATCH) 5961 list-wildcards = "%" / "*" 5963 literal = "{" number ["+"] "}" CRLF *CHAR8 5964 ; represents the number of CHAR8s. 5965 ; A non-synchronizing literal is distinguished from 5966 ; a synchronizing literal by presence of the "+" 5967 ; before the closing "}". 5968 ; Non synchronizing literals are not allowed when 5969 ; sent from server to the client. 5971 literal8 = "~{" number "}" CRLF *OCTET 5972 ; represents the number of OCTETs 5973 ; in the response string. 5975 login = "LOGIN" SP userid SP password 5977 mailbox = "INBOX" / astring 5978 ; INBOX is case-insensitive. All case variants of 5979 ; INBOX (e.g., "iNbOx") MUST be interpreted as INBOX 5980 ; not as an astring. An astring which consists of 5981 ; the case-insensitive sequence "I" "N" "B" "O" "X" 5982 ; is considered to be INBOX and not an astring. 5983 ; Refer to section 5.1 for further 5984 ; semantic details of mailbox names. 5986 mailbox-data = "FLAGS" SP flag-list / "LIST" SP mailbox-list / 5987 esearch-response / 5988 "STATUS" SP mailbox SP "(" [status-att-list] ")" / 5989 number SP "EXISTS" / Namespace-Response 5991 mailbox-list = "(" [mbx-list-flags] ")" SP 5992 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 5993 [SP mbox-list-extended] 5994 ; This is the list information pointed to by the ABNF 5995 ; item "mailbox-data", which is defined in [IMAP4] 5997 mbox-list-extended = "(" [mbox-list-extended-item 5998 *(SP mbox-list-extended-item)] ")" 6000 mbox-list-extended-item = mbox-list-extended-item-tag SP 6001 tagged-ext-val 6003 mbox-list-extended-item-tag = astring 6004 ; The content MUST conform to either "eitem-vendor-tag" 6005 ; or "eitem-standard-tag" ABNF productions. 6007 mbox-or-pat = list-mailbox / patterns 6009 mbx-list-flags = *(mbx-list-oflag SP) mbx-list-sflag 6010 *(SP mbx-list-oflag) / 6011 mbx-list-oflag *(SP mbx-list-oflag) 6013 mbx-list-oflag = "\Noinferiors" / child-mbox-flag / 6014 "\Subscribed" / "\Remote" / flag-extension 6015 ; Other flags; multiple possible per LIST response 6017 mbx-list-sflag = "\NonExistent" / "\Noselect" / "\Marked" / "\Unmarked" 6018 ; Selectability flags; only one per LIST response 6020 media-basic = ((DQUOTE ("APPLICATION" / "AUDIO" / "IMAGE" / 6021 "MESSAGE" / "VIDEO" / "FONT") DQUOTE) / string) SP 6022 media-subtype 6023 ; Defined in [MIME-IMT]. 6024 ; FONT defined in RFC YYYY. 6026 media-message = DQUOTE "MESSAGE" DQUOTE SP 6027 DQUOTE ("RFC822" / "GLOBAL") DQUOTE 6028 ; Defined in [MIME-IMT] 6030 media-subtype = string 6031 ; Defined in [MIME-IMT] 6033 media-text = DQUOTE "TEXT" DQUOTE SP media-subtype 6034 ; Defined in [MIME-IMT] 6036 message-data = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att)) 6038 move = "MOVE" SP sequence-set SP mailbox 6040 msg-att = "(" (msg-att-dynamic / msg-att-static) 6041 *(SP (msg-att-dynamic / msg-att-static)) ")" 6043 msg-att-dynamic = "FLAGS" SP "(" [flag-fetch *(SP flag-fetch)] ")" 6044 ; MAY change for a message 6046 msg-att-static = "ENVELOPE" SP envelope / "INTERNALDATE" SP date-time / 6047 "RFC822.SIZE" SP number / 6048 "BODY" ["STRUCTURE"] SP body / 6049 "BODY" section ["<" number ">"] SP nstring / 6050 "BINARY" section-binary SP (nstring / literal8) / 6051 "BINARY.SIZE" section-binary SP number / 6052 "UID" SP uniqueid 6053 ; MUST NOT change for a message 6055 Namespace = nil / "(" 1*Namespace-Descr ")" 6057 Namespace-Command = "NAMESPACE" 6059 Namespace-Descr = "(" string SP 6060 (DQUOTE QUOTED-CHAR DQUOTE / nil) 6061 [Namespace-Response-Extensions] ")" 6063 Namespace-Response-Extensions = *(Namespace-Response-Extension) 6065 Namespace-Response-Extension = SP string SP 6066 "(" string *(SP string) ")" 6068 Namespace-Response = "NAMESPACE" SP Namespace 6069 SP Namespace SP Namespace 6070 ; The first Namespace is the Personal Namespace(s). 6071 ; The second Namespace is the Other Users' 6072 ; Namespace(s). 6073 ; The third Namespace is the Shared Namespace(s). 6075 nil = "NIL" 6077 nstring = string / nil 6079 number = 1*DIGIT 6080 ; Unsigned 32-bit integer 6081 ; (0 <= n < 4,294,967,296) 6083 number64 = 1*DIGIT 6084 ; Unsigned 63-bit integer 6085 ; (0 <= n <= 9,223,372,036,854,775,807) 6087 nz-number = digit-nz *DIGIT 6088 ; Non-zero unsigned 32-bit integer 6089 ; (0 < n < 4,294,967,296) 6091 option-extension = (option-standard-tag / option-vendor-tag) 6092 [SP option-value] 6094 option-standard-tag = atom 6095 ; an option defined in a Standards Track or 6096 ; Experimental RFC 6098 option-val-comp = astring / 6099 option-val-comp *(SP option-val-comp) / 6100 "(" option-val-comp ")" 6102 option-value = "(" option-val-comp ")" 6104 option-vendor-tag = vendor-token "-" atom 6105 ; a vendor-specific option, non-standard 6107 partial-range = number ["." nz-number] 6108 ; Copied from RFC 5092 (IMAP URL) 6110 partial = "<" number "." nz-number ">" 6111 ; Partial FETCH request. 0-based offset of 6112 ; the first octet, followed by the number of octets 6113 ; in the fragment. 6115 password = astring 6117 patterns = "(" list-mailbox *(SP list-mailbox) ")" 6119 quoted = DQUOTE *QUOTED-CHAR DQUOTE 6121 QUOTED-CHAR = / 6122 "\" quoted-specials / UTF8-2 / UTF8-3 / UTF8-4 6124 quoted-specials = DQUOTE / "\" 6126 rename = "RENAME" SP mailbox SP mailbox 6127 ; Use of INBOX as a destination gives a NO error 6129 response = *(continue-req / response-data) response-done 6131 response-data = "*" SP (resp-cond-state / resp-cond-bye / 6132 mailbox-data / message-data / capability-data / 6133 enable-data) CRLF 6135 response-done = response-tagged / response-fatal 6137 response-fatal = "*" SP resp-cond-bye CRLF 6138 ; Server closes connection immediately 6140 response-tagged = tag SP resp-cond-state CRLF 6142 resp-code-apnd = "APPENDUID" SP nz-number SP append-uid 6144 resp-code-copy = "COPYUID" SP nz-number SP uid-set SP uid-set 6146 resp-cond-auth = ("OK" / "PREAUTH") SP resp-text 6147 ; Authentication condition 6149 resp-cond-bye = "BYE" SP resp-text 6151 resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text 6152 ; Status condition 6154 resp-specials = "]" 6156 resp-text = ["[" resp-text-code "]" SP] [text] 6158 resp-text-code = "ALERT" / 6159 "BADCHARSET" [SP "(" charset *(SP charset) ")" ] / 6160 capability-data / "PARSE" / 6161 "PERMANENTFLAGS" SP "(" 6162 [flag-perm *(SP flag-perm)] ")" / 6163 "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / 6164 "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number / 6165 resp-code-apnd / resp-code-copy / "UIDNOTSTICKY" / 6166 "UNAVAILABLE" / "AUTHENTICATIONFAILED" / 6167 "AUTHORIZATIONFAILED" / "EXPIRED" / 6168 "PRIVACYREQUIRED" / "CONTACTADMIN" / "NOPERM" / 6169 "INUSE" / "EXPUNGEISSUED" / "CORRUPTION" / 6170 "SERVERBUG" / "CLIENTBUG" / "CANNOT" / 6171 "LIMIT" / "OVERQUOTA" / "ALREADYEXISTS" / 6172 "NONEXISTENT" / "NOTSAVED" / 6173 "CLOSED" / 6174 "UNKNOWN-CTE" / 6175 atom [SP 1*] 6177 return-option = "SUBSCRIBED" / "CHILDREN" / status-option / 6178 option-extension 6180 search = "SEARCH" [search-return-opts] 6181 SP search-program 6183 search-correlator = SP "(" "TAG" SP tag-string ")" 6185 search-key = "ALL" / "ANSWERED" / "BCC" SP astring / 6186 "BEFORE" SP date / "BODY" SP astring / 6187 "CC" SP astring / "DELETED" / "FLAGGED" / 6188 "FROM" SP astring / "KEYWORD" SP flag-keyword / 6189 "ON" SP date / "SEEN" / 6190 "SINCE" SP date / "SUBJECT" SP astring / 6191 "TEXT" SP astring / "TO" SP astring / 6192 "UNANSWERED" / "UNDELETED" / "UNFLAGGED" / 6193 "UNKEYWORD" SP flag-keyword / "UNSEEN" / 6194 ; Above this line were in [IMAP2] 6195 "DRAFT" / "HEADER" SP header-fld-name SP astring / 6196 "LARGER" SP number / "NOT" SP search-key / 6197 "OR" SP search-key SP search-key / 6198 "SENTBEFORE" SP date / "SENTON" SP date / 6199 "SENTSINCE" SP date / "SMALLER" SP number / 6200 "UID" SP sequence-set / "UNDRAFT" / sequence-set / 6201 "(" search-key *(SP search-key) ")" 6203 search-modifier-name = tagged-ext-label 6205 search-mod-params = tagged-ext-val 6206 ; This non-terminal shows recommended syntax 6207 ; for future extensions. 6209 search-program = ["CHARSET" SP charset SP] 6210 search-key *(SP search-key) 6211 ; CHARSET argument to SEARCH MUST be 6212 ; registered with IANA. 6214 search-ret-data-ext = search-modifier-name SP search-return-value 6215 ; Note that not every SEARCH return option 6216 ; is required to have the corresponding 6217 ; ESEARCH return data. 6219 search-return-data = "MIN" SP nz-number / 6220 "MAX" SP nz-number / 6221 "ALL" SP sequence-set / 6222 "COUNT" SP number / 6223 search-ret-data-ext 6224 ; All return data items conform to 6225 ; search-ret-data-ext syntax. 6226 ; Note that "$" marker is not allowed 6227 ; after the ALL return data item. 6229 search-return-opts = SP "RETURN" SP "(" [search-return-opt 6230 *(SP search-return-opt)] ")" 6232 search-return-opt = "MIN" / "MAX" / "ALL" / "COUNT" / 6233 "SAVE" / 6234 search-ret-opt-ext 6235 ; conforms to generic search-ret-opt-ext 6236 ; syntax 6238 search-ret-opt-ext = search-modifier-name [SP search-mod-params] 6240 search-return-value = tagged-ext-val 6241 ; Data for the returned search option. 6242 ; A single "nz-number"/"number"/"number64" value 6243 ; can be returned as an atom (i.e., without 6244 ; quoting). A sequence-set can be returned 6245 ; as an atom as well. 6247 section = "[" [section-spec] "]" 6249 section-binary = "[" [section-part] "]" 6251 section-msgtext = "HEADER" / "HEADER.FIELDS" [".NOT"] SP header-list / 6252 "TEXT" 6253 ; top-level or MESSAGE/RFC822 or MESSAGE/GLOBAL part 6255 section-part = nz-number *("." nz-number) 6256 ; body part reference. 6257 ; Allows for accessing nested body parts. 6259 section-spec = section-msgtext / (section-part ["." section-text]) 6261 section-text = section-msgtext / "MIME" 6262 ; text other than actual body part (headers, etc.) 6264 select = "SELECT" SP mailbox 6266 seq-number = nz-number / "*" 6267 ; message sequence number (COPY, FETCH, STORE 6268 ; commands) or unique identifier (UID COPY, 6269 ; UID FETCH, UID STORE commands). 6270 ; * represents the largest number in use. In 6271 ; the case of message sequence numbers, it is 6272 ; the number of messages in a non-empty mailbox. 6273 ; In the case of unique identifiers, it is the 6274 ; unique identifier of the last message in the 6275 ; mailbox or, if the mailbox is empty, the 6276 ; mailbox's current UIDNEXT value. 6277 ; The server should respond with a tagged BAD 6278 ; response to a command that uses a message 6279 ; sequence number greater than the number of 6280 ; messages in the selected mailbox. This 6281 ; includes "*" if the selected mailbox is empty. 6283 seq-range = seq-number ":" seq-number 6284 ; two seq-number values and all values between 6285 ; these two regardless of order. 6286 ; Example: 2:4 and 4:2 are equivalent and indicate 6287 ; values 2, 3, and 4. 6288 ; Example: a unique identifier sequence range of 6289 ; 3291:* includes the UID of the last message in 6290 ; the mailbox, even if that value is less than 3291. 6292 sequence-set = (seq-number / seq-range) ["," sequence-set] 6293 ; set of seq-number values, regardless of order. 6294 ; Servers MAY coalesce overlaps and/or execute the 6295 ; sequence in any order. 6296 ; Example: a message sequence number set of 6297 ; 2,4:7,9,12:* for a mailbox with 15 messages is 6298 ; equivalent to 2,4,5,6,7,9,12,13,14,15 6299 ; Example: a message sequence number set of *:4,5:7 6300 ; for a mailbox with 10 messages is equivalent to 6301 ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and 6302 ; overlap coalesced to be 4,5,6,7,8,9,10. 6304 sequence-set =/ seq-last-command 6305 ; Allow for "result of the last command" indicator. 6307 seq-last-command = "$" 6309 status = "STATUS" SP mailbox SP 6310 "(" status-att *(SP status-att) ")" 6312 status-att = "MESSAGES" / "UIDNEXT" / "UIDVALIDITY" / 6313 "UNSEEN" / "DELETED" / "SIZE" 6315 status-att-val = ("MESSAGES" SP number) / 6316 ("UIDNEXT" SP nz-number) / 6317 ("UIDVALIDITY" SP nz-number) / 6318 ("UNSEEN" SP number) / 6319 ("DELETED" SP number) / 6320 ("SIZE" SP number64) 6321 ; Extensions to the STATUS responses 6322 ; should extend this production. 6323 ; Extensions should use the generic 6324 ; syntax defined by tagged-ext. 6326 status-att-list = status-att-val *(SP status-att-val) 6328 status-option = "STATUS" SP "(" status-att *(SP status-att) ")" 6329 ; This ABNF production complies with 6330 ; syntax. 6332 store = "STORE" SP sequence-set SP store-att-flags 6334 store-att-flags = (["+" / "-"] "FLAGS" [".SILENT"]) SP 6335 (flag-list / (flag *(SP flag))) 6337 string = quoted / literal 6339 subscribe = "SUBSCRIBE" SP mailbox 6341 tag = 1* 6343 tagged-ext-label = tagged-label-fchar *tagged-label-char 6344 ;; Is a valid RFC 3501 "atom". 6346 tagged-label-fchar = ALPHA / "-" / "_" / "." 6348 tagged-label-char = tagged-label-fchar / DIGIT / ":" 6350 tagged-ext-comp = astring / 6351 tagged-ext-comp *(SP tagged-ext-comp) / 6352 "(" tagged-ext-comp ")" 6353 ;; Extensions that follow this general 6354 ;; syntax should use nstring instead of 6355 ;; astring when appropriate in the context 6356 ;; of the extension. 6357 ;; Note that a message set or a "number" 6358 ;; can always be represented as an "atom". 6359 ;; An URL should be represented as 6360 ;; a "quoted" string. 6362 tagged-ext-simple = sequence-set / number / number64 6364 tagged-ext-val = tagged-ext-simple / 6365 "(" [tagged-ext-comp] ")" 6367 text = 1*TEXT-CHAR 6369 TEXT-CHAR = 6371 time = 2DIGIT ":" 2DIGIT ":" 2DIGIT 6372 ; Hours minutes seconds 6374 uid = "UID" SP 6375 (copy / move / fetch / search / store / uid-expunge) 6376 ; Unique identifiers used instead of message 6377 ; sequence numbers 6379 uid-expunge = "EXPUNGE" SP sequence-set 6380 ; Unique identifiers used instead of message 6381 ; sequence numbers 6383 uid-set = (uniqueid / uid-range) *("," uid-set) 6385 uid-range = (uniqueid ":" uniqueid) 6386 ; two uniqueid values and all values 6387 ; between these two regards of order. 6388 ; Example: 2:4 and 4:2 are equivalent. 6390 uniqueid = nz-number 6391 ; Strictly ascending 6393 unsubscribe = "UNSUBSCRIBE" SP mailbox 6395 userid = astring 6397 UTF8-2 = 6399 UTF8-3 = 6401 UTF8-4 = 6403 x-command = "X" atom 6405 zone = ("+" / "-") 4DIGIT 6406 ; Signed four-digit value of hhmm representing 6407 ; hours and minutes east of Greenwich (that is, 6408 ; the amount that the given time differs from 6409 ; Universal Time). Subtracting the timezone 6410 ; from the given time will give the UT form. 6411 ; The Universal Time zone is "+0000". 6413 10. Author's Note 6415 This document is a revision or rewrite of earlier documents, and 6416 supercedes the protocol specification in those documents: RFC 2060, 6417 RFC 1730, unpublished IMAP2bis.TXT document, RFC 1176, and RFC 1064. 6419 11. Security Considerations 6421 IMAP4rev2 protocol transactions, including electronic mail data, are 6422 sent in the clear over the network unless protection from snooping is 6423 negotiated. This can be accomplished either by the use of IMAPS 6424 service, STARTTLS command, negotiated privacy protection in the 6425 AUTHENTICATE command, or some other protection mechanism. 6427 11.1. STARTTLS Security Considerations 6429 IMAP client and server implementations MUST comply with relevant TLS 6430 recommendations from [RFC8314]. Additionally, when using TLS 1.2, 6431 IMAP implementations MUST implement 6432 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite, and SHOULD 6433 implement the TLS_RSA_WITH_AES_128_CBC_SHA [TLS] cipher suite. This 6434 is important as it assures that any two compliant implementations can 6435 be configured to interoperate. Other TLS cipher suites recommended 6436 in RFC 7525 are RECOMMENDED: TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 6437 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 and 6438 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384. All other cipher suites are 6439 OPTIONAL. Note that this is a change from section 2.1 of [IMAP-TLS]. 6441 During the [TLS] negotiation, the client MUST check its understanding 6442 of the server hostname against the server's identity as presented in 6443 the server Certificate message, in order to prevent man-in-the-middle 6444 attacks. This procedure is described in [RFC7817]. 6446 Both the client and server MUST check the result of the STARTTLS 6447 command and subsequent [TLS] negotiation to see whether acceptable 6448 authentication and/or privacy was achieved. 6450 11.2. COPYUID and APPENDUID response codes 6452 The COPYUID and APPENDUID response codes return information about the 6453 mailbox, which may be considered sensitive if the mailbox has 6454 permissions set that permit the client to COPY or APPEND to the 6455 mailbox, but not SELECT or EXAMINE it. 6457 Consequently, these response codes SHOULD NOT be issued if the client 6458 does not have access to SELECT or EXAMINE the mailbox. 6460 11.3. LIST command and Other Users' namespace 6462 In response to a LIST command containing an argument of the Other 6463 Users' Namespace prefix, a server SHOULD NOT list users that have not 6464 granted list access to their personal mailboxes to the currently 6465 authenticated user. Providing such a list, could compromise security 6466 by potentially disclosing confidential information of who is located 6467 on the server, or providing a starting point of a list of user 6468 accounts to attack. 6470 11.4. Other Security Considerations 6472 A server error message for an AUTHENTICATE command which fails due to 6473 invalid credentials SHOULD NOT detail why the credentials are 6474 invalid. 6476 Use of the LOGIN command sends passwords in the clear. This can be 6477 avoided by using the AUTHENTICATE command with a [SASL] mechanism 6478 that does not use plaintext passwords, by first negotiating 6479 encryption via STARTTLS or some other protection mechanism. 6481 A server implementation MUST implement a configuration that, at the 6482 time of authentication, requires: 6483 (1) The STARTTLS command has been negotiated. 6484 OR 6485 (2) Some other mechanism that protects the session from password 6486 snooping has been provided. 6487 OR 6488 (3) The following measures are in place: 6489 (a) The LOGINDISABLED capability is advertised, and [SASL] mechanisms 6490 (such as PLAIN) using plaintext passwords are NOT advertised in the 6491 CAPABILITY list. 6492 AND 6493 (b) The LOGIN command returns an error even if the password is 6494 correct. 6495 AND 6496 (c) The AUTHENTICATE command returns an error with all [SASL] 6497 mechanisms that use plaintext passwords, even if the password is 6498 correct. 6500 A server error message for a failing LOGIN command SHOULD NOT specify 6501 that the user name, as opposed to the password, is invalid. 6503 A server SHOULD have mechanisms in place to limit or delay failed 6504 AUTHENTICATE/LOGIN attempts. 6506 Additional security considerations are discussed in the section 6507 discussing the AUTHENTICATE and LOGIN commands. 6509 12. IANA Considerations 6511 IANA is requested to update "Service Names and Transport Protocol 6512 Port Numbers" registry as follows: 6514 1. Registration for TCP "imap" port 143 should be updated to point 6515 to this document and RFC 3501. 6517 2. Registration for TCP "imaps" port 993 should be updated to point 6518 to this document, RFC 8314 and RFC 3501. 6520 3. Both UDP port 143 and UDP port 993 should be marked as "Reserved" 6521 in the registry. 6523 Additional IANA actions are specified in subsection of this section. 6525 12.1. Updates to IMAP4 Capabilities registry 6527 IMAP4 capabilities are registered by publishing a standards track or 6528 IESG approved informational or experimental RFC. The registry is 6529 currently located at: http://www.iana.org/assignments/ 6530 imap4-capabilities 6532 As this specification revises the STARTTLS and LOGINDISABLED 6533 extensions previously defined in [IMAP-TLS], IANA is requested to 6534 update registry entries for these 2 extensions to point to this 6535 document. 6537 12.2. GSSAPI/SASL service name 6539 GSSAPI/Kerberos/SASL service names are registered by publishing a 6540 standards track or IESG approved experimental RFC. The registry is 6541 currently located at: http://www.iana.org/assignments/gssapi-service- 6542 names 6544 IANA is requested to update the "imap" service name previously 6545 registered in RFC 3501, to point to this document. 6547 13. References 6549 13.1. Normative References 6551 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6552 Specifications: ABNF", STD 68, RFC 5234, January 2008, 6553 . 6555 [ANONYMOUS] 6556 Zeilenga, K., "Anonymous Simple Authentication and 6557 Security Layer (SASL) Mechanism", RFC 4505, June 2006, 6558 . 6560 [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration 6561 Procedures", BCP 19, RFC 2978, October 2000, 6562 . 6564 [SCRAM-SHA-256] 6565 Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple 6566 Authentication and Security Layer (SASL) Mechanisms", 6567 RFC 7677, DOI 10.17487/RFC7677, November 2015, 6568 . 6570 [DISPOSITION] 6571 Troost, R., Dorner, S., and K. Moore, Ed., "Communicating 6572 Presentation Information in Internet Messages: The 6573 Content-Disposition Header Field", RFC 2183, August 1997, 6574 . 6576 [PLAIN] Zeilenga, K., Ed., "The PLAIN Simple Authentication and 6577 Security Layer (SASL) Mechanism", RFC 4616, August 2006, 6578 . 6580 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6581 Requirement Levels", BCP 14, RFC 2119, 6582 DOI 10.17487/RFC2119, March 1997, 6583 . 6585 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 6586 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 6587 May 2017, . 6589 [LANGUAGE-TAGS] 6590 Alvestrand, H., "Content Language Headers", RFC 3282, May 6591 2002, . 6593 [LOCATION] 6594 Palme, J., Hopmann, A., and N. Shelness, "MIME 6595 Encapsulation of Aggregate Documents, such as HTML 6596 (MHTML)", RFC 2557, March 1999, 6597 . 6599 [MD5] Myers, J. and M. Rose, "The Content-MD5 Header Field", 6600 RFC 1864, October 1995, 6601 . 6603 [MIME-HDRS] 6604 Moore, K., "MIME (Multipurpose Internet Mail Extensions) 6605 Part Three: Message Header Extensions for Non-ASCII Text", 6606 RFC 2047, November 1996, 6607 . 6609 [MIME-IMB] 6610 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6611 Extensions (MIME) Part One: Format of Internet Message 6612 Bodies", RFC 2045, November 1996, 6613 . 6615 [MIME-IMT] 6616 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6617 Extensions (MIME) Part Two: Media Types", RFC 2046, 6618 November 1996, . 6620 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 6621 Word Extensions: Character Sets, Languages, and 6622 Continuations", RFC 2231, DOI 10.17487/RFC2231, November 6623 1997, . 6625 [RFC-5322] 6626 Resnick, P., Ed., "Internet Message Format", RFC 5322, 6627 October 2008, . 6629 [SASL] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 6630 Authentication and Security Layer (SASL)", RFC 4422, June 6631 2006, . 6633 [TLS] Dierks, T. and E. Rescorla, "The Transport Layer Security 6634 (TLS) Protocol Version 1.2", RFC 5246, August 2008, 6635 . 6637 [UTF-7] Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe 6638 Transformation Format of Unicode", RFC 2152, May 1997, 6639 . 6641 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 6642 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 6643 2003, . 6645 [MULTIAPPEND] 6646 Crispin, M., "Internet Message Access Protocol (IMAP) - 6647 MULTIAPPEND Extension", RFC 3502, March 2003, 6648 . 6650 [NET-UNICODE] 6651 Klensin, J. and M. Padlipsky, "Unicode Format for Network 6652 Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008, 6653 . 6655 [I18N-HDRS] 6656 Yang, A., Steele, S., and N. Freed, "Internationalized 6657 Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 6658 2012, . 6660 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 6661 Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, 6662 . 6664 [RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS) 6665 Server Identity Check Procedure for Email-Related 6666 Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016, 6667 . 6669 [RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition 6670 Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, 6671 February 2017, . 6673 [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: 6674 Use of Transport Layer Security (TLS) for Email Submission 6675 and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, 6676 . 6678 [IMAP-IMPLEMENTATION] 6679 Leiba, B., "IMAP4 Implementation Recommendations", 6680 RFC 2683, September 1999, 6681 . 6683 [IMAP-MULTIACCESS] 6684 Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", 6685 RFC 2180, July 1997, 6686 . 6688 13.2. Informative References (related protocols) 6690 [RFC5256] Crispin, M. and K. Murchison, "Internet Message Access 6691 Protocol - SORT and THREAD Extensions", RFC 5256, 6692 DOI 10.17487/RFC5256, June 2008, 6693 . 6695 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access 6696 Protocol version 4 - LIST Command Extensions", RFC 5258, 6697 DOI 10.17487/RFC5258, June 2008, 6698 . 6700 [RFC2193] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 6701 DOI 10.17487/RFC2193, September 1997, 6702 . 6704 [RFC3348] Gahrns, M. and R. Cheng, "The Internet Message Action 6705 Protocol (IMAP4) Child Mailbox Extension", RFC 3348, 6706 DOI 10.17487/RFC3348, July 2002, 6707 . 6709 [RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals", 6710 RFC 7888, DOI 10.17487/RFC7888, May 2016, 6711 . 6713 [IMAP-DISC] 6714 Melnikov, A., Ed., "Synchronization Operations for 6715 Disconnected IMAP4 Clients", RFC 4549, June 2006, 6716 . 6718 [IMAP-I18N] 6719 Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 6720 Message Access Protocol Internationalization", RFC 5255, 6721 DOI 10.17487/RFC5255, June 2008, 6722 . 6724 [IMAP-MODEL] 6725 Crispin, M., "Distributed Electronic Mail Models in 6726 IMAP4", RFC 1733, December 1994, 6727 . 6729 [IMAP-UTF-8] 6730 Resnick, P., Ed., Newman, C., Ed., and S. Shen, Ed., "IMAP 6731 Support for UTF-8", RFC 6855, DOI 10.17487/RFC6855, March 6732 2013, . 6734 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 6735 October 2008, . 6737 [RFC3516] Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516, 6738 DOI 10.17487/RFC3516, April 2003, 6739 . 6741 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 6742 RFC 4314, December 2005, 6743 . 6745 [RFC2087] Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 6746 1997, . 6748 [IMAP-URL] 6749 Melnikov, A., Ed. and C. Newman, "IMAP URL Scheme", 6750 RFC 5092, DOI 10.17487/RFC5092, November 2007, 6751 . 6753 13.3. Informative References (historical aspects of IMAP and related 6754 protocols) 6756 [IMAP-COMPAT] 6757 Crispin, M., "IMAP4 Compatibility with IMAP2bis", 6758 RFC 2061, December 1996, 6759 . 6761 [IMAP-HISTORICAL] 6762 Crispin, M., "IMAP4 Compatibility with IMAP2 and 6763 IMAP2bis", RFC 1732, December 1994, 6764 . 6766 [IMAP-OBSOLETE] 6767 Crispin, M., "Internet Message Access Protocol - Obsolete 6768 Syntax", RFC 2062, December 1996, 6769 . 6771 [IMAP2] Crispin, M., "Interactive Mail Access Protocol: Version 6772 2", RFC 1176, August 1990, 6773 . 6775 [RFC-822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET 6776 TEXT MESSAGES", STD 11, RFC 822, August 1982, 6777 . 6779 [IMAP-TLS] 6780 Newman, C., "Using TLS with IMAP, POP3 and ACAP", 6781 RFC 2595, June 1999, 6782 . 6784 Appendix A. Backward compatibility with IMAP4rev1 6786 An implementation that wants to remain compatible with IMAP4rev1 can 6787 advertise both IMAP4rev1 and IMAP4rev2 in its CAPABILITY response/ 6788 response code. While some IMAP4rev1 responses were removed in 6789 IMAP4rev2, their presence will not break IMAP4rev2-only clients. 6791 If both IMAP4rev1 and IMAP4rev2 are advertised, an IMAP client that 6792 wants to use IMAP4rev2 MUST issue an "ENABLE IMAP4rev2" command. 6794 Servers advertising both IMAP4rev1 and IMAP4rev2 SHOULD NOT generate 6795 UTF-8 quoted strings unless the client has issued "ENABLE IMAP4rev2". 6796 Consider implementation of mechanisms described or referenced in 6797 [IMAP-UTF-8] to achieve this goal. 6799 Servers advertising both IMAP4rev1 and IMAP4rev2, and clients 6800 intending to be compatible with IMAP4rev1 servers MUST be compatible 6801 with the international mailbox naming convention described in the 6802 following subsection. 6804 A.1. Mailbox International Naming Convention for compatibility with 6805 IMAP4rev1 6807 Support for the Mailbox International Naming Convention described in 6808 this section is not required for IMAP4rev2-only clients and servers. 6810 By convention, international mailbox names in IMAP4rev1 are specified 6811 using a modified version of the UTF-7 encoding described in [UTF-7]. 6812 Modified UTF-7 may also be usable in servers that implement an 6813 earlier version of this protocol. 6815 In modified UTF-7, printable US-ASCII characters, except for "&", 6816 represent themselves; that is, characters with octet values 0x20-0x25 6817 and 0x27-0x7e. The character "&" (0x26) is represented by the two- 6818 octet sequence "&-". 6820 All other characters (octet values 0x00-0x1f and 0x7f-0xff) are 6821 represented in modified BASE64, with a further modification from 6822 [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be 6823 used to represent any printing US-ASCII character which can represent 6824 itself. Only characters inside the modified BASE64 alphabet are 6825 permitted in modified BASE64 text. 6827 "&" is used to shift to modified BASE64 and "-" to shift back to US- 6828 ASCII. There is no implicit shift from BASE64 to US-ASCII, and null 6829 shifts ("-&" while in BASE64; note that "&-" while in US-ASCII means 6830 "&") are not permitted. However, all names start in US-ASCII, and 6831 MUST end in US-ASCII; that is, a name that ends with a non-ASCII 6832 ISO-10646 character MUST end with a "-"). 6834 The purpose of these modifications is to correct the following 6835 problems with UTF-7: 6837 1. UTF-7 uses the "+" character for shifting; this conflicts with 6838 the common use of "+" in mailbox names, in particular USENET 6839 newsgroup names. 6841 2. UTF-7's encoding is BASE64 which uses the "/" character; this 6842 conflicts with the use of "/" as a popular hierarchy delimiter. 6844 3. UTF-7 prohibits the unencoded usage of "\"; this conflicts with 6845 the use of "\" as a popular hierarchy delimiter. 6847 4. UTF-7 prohibits the unencoded usage of "~"; this conflicts with 6848 the use of "~" in some servers as a home directory indicator. 6850 5. UTF-7 permits multiple alternate forms to represent the same 6851 string; in particular, printable US-ASCII characters can be 6852 represented in encoded form. 6854 Although modified UTF-7 is a convention, it establishes certain 6855 requirements on server handling of any mailbox name with an embedded 6856 "&" character. In particular, server implementations MUST preserve 6857 the exact form of the modified BASE64 portion of a modified UTF-7 6858 name and treat that text as case-sensitive, even if names are 6859 otherwise case-insensitive or case-folded. 6861 Server implementations SHOULD verify that any mailbox name with an 6862 embedded "&" character, used as an argument to CREATE, is: in the 6863 correctly modified UTF-7 syntax, has no superfluous shifts, and has 6864 no encoding in modified BASE64 of any printing US-ASCII character 6865 which can represent itself. However, client implementations MUST NOT 6866 depend upon the server doing this, and SHOULD NOT attempt to create a 6867 mailbox name with an embedded "&" character unless it complies with 6868 the modified UTF-7 syntax. 6870 Server implementations which export a mail store that does not follow 6871 the modified UTF-7 convention MUST convert to modified UTF-7 any 6872 mailbox name that contains either non-ASCII characters or the "&" 6873 character. 6875 For example, here is a mailbox name which mixes English, Chinese, 6876 and Japanese text: ~peter/mail/&U,BTFw-/&ZeVnLIqe- 6878 For example, the string "&Jjo!" is not a valid mailbox name 6879 because it does not contain a shift to US-ASCII before the "!". 6880 The correct form is "&Jjo-!". The string "&U,BTFw-&ZeVnLIqe-" is 6881 not permitted because it contains a superfluous shift. The 6882 correct form is "&U,BTF2XlZyyKng-". 6884 Appendix B. Backward compatibility with BINARY extension 6886 IMAP4rev2 is incorporates subset of functionality provided by the 6887 BINARY extension [RFC3516], in particular it includes additional 6888 FETCH items (BINARY, BINARY.PEEK and BINARY.SIZE), but not extensions 6889 to the APPEND command. IMAP4rev2 implementations that supports full 6890 RFC 3516 functionality need to also advertise the BINARY token in the 6891 CAPABILITY response. 6893 Appendix C. Changes from RFC 3501 / IMAP4rev1 6895 The following is the plan for remaining changes. The plan might 6896 change over time. 6898 1. Fold in the following extensions/RFC: RFC 5530 (IMAP Response 6899 Codes, done), UIDPLUS (done), ENABLE (done), ESEARCH (done), 6900 SPECIAL-USE (list of new mailbox attributes is done), LITERAL- 6901 (done), NAMESPACE (done), SASL-IR (done), IDLE (done), MOVE 6902 (done). 6904 2. Add CLOSED response code (from CONDSTORE) - done 6906 3. Add support for $MDNSent and $Forwarded IMAP keywords - done. 6907 Add more examples showing their use? Also add other keywords 6908 like $Phishing, $Junk, $NonJunk? 6910 4. Require all unsolicited FETCH updates to include UID - done. 6912 5. Update recommendations on TLS ciphers to match UTA WG work (as 6913 per RFC 8314, RFC 7525 and RFC 7817) - done. 6915 6. Possibly fold in the following extensions/RFC: Base LIST- 6916 EXTENDED syntax plus deprecate LSUB (replace it with LIST 6917 \Subscribed) minus the requirement to support multiple list 6918 patterns - done, STATUS-in-LIST - done, SEARCHRES, BINARY (only 6919 the FETCH changes on leaf body part and make APPEND related ones 6920 optional. See the mailing list discussion) - done. 6922 7. Add STATUS SIZE (total mailbox size) - done. Add STATUS DELETED 6923 (number of messages with \Deleted flag set) - done. 6925 8. Drop UTF-7, all mailboxes are always in UTF-8 - done. 6927 9. Revise IANA registration of IMAP extensions and give advice on 6928 use of "X-" convention. 6930 10. Allow word-based searching (as per Chris Newman)? Need to 6931 discuss header field search, where exact/substring match is 6932 still required for interoperability. 6934 The following changes since RFC 3501 were done so far: 6936 1. Folded in IMAP UNSELECT (RFC 3691), UIDPLUS (RFC 4315), ESEARCH 6937 (RFC 4731), ENABLE (RFC 5161), IDLE (RFC 2177), SASL-IR (RFC 6938 4959), LIST-STATUS (RFC 5819) and MOVE (RFC 6851) extensions. 6939 Also folded RFC 5530 and FETCH side of the BINARY extension (RFC 6940 3516). 6942 2. Clarified that server should decode parameter value 6943 continuations as described in [RFC2231]. This requirement was 6944 hidden in RFC 2231 itself. 6946 3. SEARCH command now requires to return ESEARCH response (SEARCH 6947 response is now deprecated). 6949 4. Added CLOSED response code from RFC 7162. SELECT/EXAMINE when a 6950 mailbox is already selected now require for the CLOSED response 6951 code to be returned. 6953 5. Updated to use modern TLS-related recommendations as per RFC 6954 8314, RFC 7817, RFC 7525. 6956 6. For future extensibility extended ABNF for tagged-ext-simple to 6957 allow for bare number64. 6959 7. Added SHOULD level requirement on IMAP servers to support 6960 $MDNSent and $Forwarded keywords. 6962 8. Added STATUS SIZE and STATUS DELETED. 6964 9. Mailbox names and message headers now allow for UTF-8. Support 6965 for Modified UTF-7 in mailbox names is not required, unless 6966 compatibility with IMAP4rev1 is desired. 6968 10. UNSEEN response code on SELECT/EXAMINE is now deprecated. 6970 11. RECENT response on SELECT/EXAMINE, \Recent flag, RECENT STATUS, 6971 SEARCH NEW items are now deprecated. 6973 12. Clarified that the server doesn't need to send a new 6974 PERMANENTFLAGS response code when a new keyword was successfully 6975 added and the server advertised \* earlier for the same mailbox. 6977 13. Removed the CHECK command. Clients should use NOOP instead. 6979 14. RFC822, RFC822.HEADER and RFC822.TEXT FETCH data items were 6980 deprecated. Clients should use the corresponding BODY[] 6981 variants instead. 6983 15. Replaced DIGEST-MD5 SASL mechanism with SCRAM-SHA-256. DIGEST- 6984 MD5 was deprecated. 6986 16. LSUB command was deprecated. Clients should use LIST 6987 (SUBSCRIBED) instead. 6989 17. resp-text ABNF non terminal was updated to allow for empty text. 6991 18. IDLE command can now return updates not related to the currently 6992 selected mailbox state. 6994 Appendix D. Acknowledgement 6996 Earlier versions of this document were edited by Mark Crispin. 6997 Sadly, he is no longer available to help with this work. Editors of 6998 this revisions are hoping that Mark would have approved. 7000 Chris Newman has contributed text on I18N and use of UTF-8 in 7001 messages and mailbox names. 7003 Thank you to Tony Hansen for helping with the index generation. 7004 Thank you to Timo Sirainen, Bron Gondwana and Arnt Gulbrandsen for 7005 extensive feedback. 7007 This document incorporate text from RFC 4315 (by Mark Crispin), RFC 7008 4466 (by Cyrus Daboo), RFC 4731 (by Dave Cridland), RFC 5161 (by Arnt 7009 Gulbrandsen), RFC 5530 (by Arnt Gulbrandsen), RFC 5819 (by Timo 7010 Sirainen), RFC 6154 (by Jamie Nicolson) so work done by authors/ 7011 editors of these documents is appreciated. Note that editors of this 7012 document were redacted from the above list. 7014 Index 7016 $ 7017 $Forwarded (predefined flag) 12 7018 $MDNSent (predefined flag) 12 7020 + 7021 +FLAGS 90 7022 +FLAGS.SILENT 90 7024 - 7025 -FLAGS 90 7026 -FLAGS.SILENT 90 7028 A 7029 ALERT (response code) 97 7030 ALL (fetch item) 86 7031 ALL (search key) 76 7032 ALL (search result option) 74 7033 ALREADYEXISTS (response code) 97 7034 ANSWERED (search key) 76 7035 APPEND (command) 66 7036 APPENDUID (response code) 97 7037 AUTHENTICATE (command) 28 7038 AUTHENTICATIONFAILED (response code) 98 7039 AUTHORIZATIONFAILED (response code) 98 7041 B 7042 BAD (response) 106 7043 BADCHARSET (response code) 99 7044 BCC (search key) 76 7045 BEFORE (search key) 76 7046 BINARY.PEEK[]<> (fetch item) 86 7047 BINARY.SIZE[] (fetch item) 86 7048 BINARY.SIZE[] (fetch result) 116 7049 BINARY[]<> (fetch result) 115 7050 BINARY[]<> (fetch item) 86 7051 BODY (fetch item) 87 7052 BODY (fetch result) 116 7053 BODY (search key) 76 7054 BODY.PEEK[
]<> (fetch item) 89 7055 BODYSTRUCTURE (fetch item) 89 7056 BODYSTRUCTURE (fetch result) 117 7057 BODY[
]<> (fetch result) 116 7058 BODY[
]<> (fetch item) 87 7059 BYE (response) 106 7060 Body Structure (message attribute) 13 7062 C 7063 CANNOT (response code) 99 7064 CAPABILITY (command) 24 7065 CAPABILITY (response code) 99 7066 CAPABILITY (response) 107 7067 CC (search key) 76 7068 CLIENTBUG (response code) 99 7069 CLOSE (command) 71 7070 CLOSED (response code) 99 7071 CONTACTADMIN (response code) 100 7072 COPY (command) 90 7073 COPYUID (response code) 100 7074 CORRUPTION (response code) 100 7075 COUNT (search result option) 74 7076 CREATE (command) 37 7078 D 7079 DELETE (command) 38 7080 DELETED (search key) 76 7081 DELETED (status item) 66 7082 DRAFT (search key) 76 7084 E 7085 ENABLE (command) 32 7086 ENVELOPE (fetch item) 89 7087 ENVELOPE (fetch result) 119 7088 ESEARCH (response) 113 7089 EXAMINE (command) 36 7090 EXPIRED (response code) 101 7091 EXPUNGE (command) 72 7092 EXPUNGE (response) 114 7093 EXPUNGEISSUED (response code) 101 7094 Envelope Structure (message attribute) 13 7096 F 7097 FAST (fetch item) 86 7098 FETCH (command) 85 7099 FETCH (response) 115 7100 FLAGGED (search key) 76 7101 FLAGS (fetch item) 89 7102 FLAGS (fetch result) 120 7103 FLAGS (response) 113 7104 FLAGS (store command data item) 90 7105 FLAGS.SILENT (store command data item) 90 7106 FROM (search key) 76 7107 FULL (fetch item) 86 7108 Flags (message attribute) 11 7110 H 7111 HEADER (part specifier) 87 7112 HEADER (search key) 76 7113 HEADER.FIELDS (part specifier) 87 7114 HEADER.FIELDS.NOT (part specifier) 87 7116 I 7117 IDLE (command) 69 7118 INTERNALDATE (fetch item) 89 7119 INTERNALDATE (fetch result) 120 7120 INUSE (response code) 101 7121 Internal Date (message attribute) 12 7123 K 7124 KEYWORD (search key) 77 7125 Keyword (type of flag) 12 7127 L 7128 LARGER (search key) 77 7129 LIMIT (response code) 101 7130 LIST (command) 42 7131 LIST (response) 108 7132 LOGOUT (command) 26 7134 M 7135 MAX (search result option) 74 7136 MAY (specification requirement term) 5 7137 MESSAGES (status item) 66 7138 MIME (part specifier) 88 7139 MIN (search result option) 74 7140 MOVE (command) 91 7141 MUST (specification requirement term) 5 7142 MUST NOT (specification requirement term) 5 7143 Message Sequence Number (message attribute) 11 7145 N 7146 NAMESPACE (command) 60 7147 NAMESPACE (response) 112 7148 NO (response) 105 7149 NONEXISTENT (response code) 102 7150 NOOP (command) 25 7151 NOPERM (response code) 102 7152 NOT (search key) 77 7153 NOT RECOMMENDED (specification requirement term) 5 7155 O 7156 OK (response) 105 7157 ON (search key) 77 7158 OPTIONAL (specification requirement term) 5 7159 OR (search key) 77 7160 OVERQUOTA (response code) 102 7162 P 7163 PARSE (response code) 102 7164 PERMANENTFLAGS (response code) 102 7165 PREAUTH (response) 106 7166 PRIVACYREQUIRED (response code) 103 7167 Permanent Flag (class of flag) 12 7168 Predefined keywords 12 7170 R 7171 READ-ONLY (response code) 103 7172 READ-WRITE (response code) 103 7173 RECOMMENDED (specification requirement term) 5 7174 RENAME (command) 39 7175 REQUIRED (specification requirement term) 5 7176 RFC822.SIZE (fetch item) 89 7177 RFC822.SIZE (fetch result) 121 7179 S 7180 SAVE (search result option) 74 7181 SEARCH (command) 73 7182 SEEN (search key) 77 7183 SELECT (command) 34 7184 SENTBEFORE (search key) 77 7185 SENTON (search key) 77 7186 SENTSINCE (search key) 77 7187 SERVERBUG (response code) 103 7188 SHOULD (specification requirement term) 5 7189 SHOULD NOT (specification requirement term) 5 7190 SINCE (search key) 77 7191 SIZE (status item) 66 7192 SMALLER (search key) 77 7193 STARTTLS (command) 27 7194 STATUS (command) 65 7195 STATUS (response) 112 7196 STORE (command) 89 7197 SUBJECT (search key) 77 7198 SUBSCRIBE (command) 41 7199 Session Flag (class of flag) 12 7200 System Flag (type of flag) 11 7202 T 7203 TEXT (part specifier) 87 7204 TEXT (search key) 77 7205 TO (search key) 77 7206 TRYCREATE (response code) 103 7208 U 7209 UID (command) 93 7210 UID (fetch item) 89 7211 UID (fetch result) 121 7212 UID (search key) 78 7213 UIDNEXT (response code) 104 7214 UIDNEXT (status item) 66 7215 UIDNOTSTICKY (response code) 104 7216 UIDVALIDITY (response code) 104 7217 UIDVALIDITY (status item) 66 7218 UNANSWERED (search key) 78 7219 UNAVAILABLE (response code) 104 7220 UNDELETED (search key) 78 7221 UNDRAFT (search key) 78 7222 UNFLAGGED (search key) 78 7223 UNKEYWORD (search key) 78 7224 UNKNOWN-CTE (response code) 104 7225 UNSEEN (search key) 78 7226 UNSEEN (status item) 66 7227 UNSELECT (command) 72 7228 UNSUBSCRIBE (command) 42 7229 Unique Identifier (UID) (message attribute) 9 7231 X 7232 X (command) 95 7234 [ 7235 [RFC-5322] Size (message attribute) 13 7237 \ 7238 \All (mailbox name attribute) 110 7239 \Answered (system flag) 11 7240 \Archive (mailbox name attribute) 110 7241 \Deleted (system flag) 11 7242 \Draft (system flag) 12 7243 \Drafts (mailbox name attribute) 110 7244 \Flagged (mailbox name attribute) 111 7245 \Flagged (system flag) 11 7246 \HasChildren (mailbox name attribute) 109 7247 \HasNoChildren (mailbox name attribute) 109 7248 \Junk (mailbox name attribute) 111 7249 \Marked (mailbox name attribute) 110 7250 \Noinferiors (mailbox name attribute) 109 7251 \NonExistent (mailbox name attribute) 109 7252 \Noselect (mailbox name attribute) 109 7253 \Recent (system flag) 12 7254 \Remote (mailbox name attribute) 110 7255 \Seen (system flag) 11 7256 \Sent (mailbox name attribute) 111 7257 \Subscribed (mailbox name attribute) 110 7258 \Trash (mailbox name attribute) 111 7259 \Unmarked (mailbox name attribute) 110 7261 Authors' Addresses 7263 Alexey Melnikov (editor) 7264 Isode Ltd 7265 14 Castle Mews 7266 Hampton, Middlesex TW12 2NP 7267 UK 7269 Email: Alexey.Melnikov@isode.com 7271 Barry Leiba (editor) 7272 Huawei Technologies 7274 Phone: +1 646 827 0648 7275 Email: barryleiba@computer.org 7276 URI: http://internetmessagingtechnology.org/