idnits 2.17.00 (12 Aug 2021) /tmp/idnits33843/draft-ietf-extra-imap4rev2-17.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack an Introduction section. ** There are 3 instances of too long lines in the document, the longest one being 2 characters in excess of 72. -- The draft header indicates that this document obsoletes RFC3501, but the abstract doesn't seem to mention this, which it should. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document seems to contain a disclaimer for pre-RFC5378 work, but was first submitted on or after 10 November 2008. The disclaimer is usually necessary only for documents that revise or obsolete older RFCs, and that take significant amounts of text from those RFCs. If you can contact all authors of the source material and they are willing to grant the BCP78 rights to the IETF Trust, you can and should remove the disclaimer. Otherwise, the disclaimer is needed and you can ignore this comment. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (July 29, 2020) is 660 days in the past. Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. 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 7018, but not defined == Missing Reference: 'IMAP-OBSOLETE' is mentioned on line 7013, but not defined == Missing Reference: 'IMAP-COMPAT' is mentioned on line 7003, but not defined == Missing Reference: 'IMAP-HISTORICAL' is mentioned on line 7008, but not defined == Missing Reference: 'RFC-822' is mentioned on line 7022, but not defined ** Obsolete undefined reference: RFC 822 (Obsoleted by RFC 2822) == Missing Reference: 'IMAP-MODEL' is mentioned on line 6952, but not defined == Missing Reference: 'IMAP-DISC' is mentioned on line 6941, but not defined == Missing Reference: 'RFC3503' is mentioned on line 6914, but not defined == Missing Reference: 'IMAP-KEYWORDS-REG' is mentioned on line 6981, but not defined == Missing Reference: 'SMTP' is mentioned on line 6962, but not defined == Missing Reference: 'RFC7888' is mentioned on line 6937, but not defined -- Looks like a reference, but probably isn't: '1' on line 886 == Missing Reference: 'IMAP-URL' is mentioned on line 6976, but not defined == Missing Reference: 'UIDVALIDITY 3857529045' is mentioned on line 5727, but not defined == Missing Reference: 'UIDNEXT 4392' is mentioned on line 1727, but not defined == Missing Reference: 'RFC2193' is mentioned on line 6924, but not defined == Missing Reference: 'RFC3348' is mentioned on line 7280, but not defined ** Obsolete undefined reference: RFC 3348 (Obsoleted by RFC 5258) == Missing Reference: 'RFC4314' is mentioned on line 6969, but not defined == Missing Reference: 'RFC3501' is mentioned on line 6999, but not defined ** Obsolete undefined reference: RFC 3501 (Obsoleted by RFC 9051) == Missing Reference: 'UIDNEXT 2' is mentioned on line 3244, but not defined == Missing Reference: 'UIDVALIDITY 1' is mentioned on line 3315, but not defined == Missing Reference: 'CHARSET-REG' is mentioned on line 6991, but not defined == Missing Reference: 'IMAP-I18N' is mentioned on line 6946, but not defined == Missing Reference: 'HEADER' is mentioned on line 5744, but not defined == Missing Reference: 'BADCHARSET UTF-8' is mentioned on line 3892, but not defined == Missing Reference: 'UID' is mentioned on line 4310, but not defined == Missing Reference: 'RFC2087' is mentioned on line 6973, but not defined ** Obsolete undefined reference: RFC 2087 (Obsoleted by RFC 9208) == Missing Reference: 'IMAP-MAILBOX-NAME-ATTRS-REG' is mentioned on line 6986, but not defined == Missing Reference: 'READ-WRITE' is mentioned on line 5728, but not defined == Missing Reference: 'RFC4422' is mentioned on line 6077, but not defined == Missing Reference: 'IMAP4' is mentioned on line 6162, but not defined == Missing Reference: 'Namespace-Response-Extensions' is mentioned on line 6232, but not defined == Missing Reference: 'IMAP-TLS' is mentioned on line 7026, but not defined == Missing Reference: 'RFCXXXX' is mentioned on line 6758, but not defined == Missing Reference: 'RFC5465' is mentioned on line 6933, but not defined == Missing Reference: 'RFC5256' is mentioned on line 6919, but not defined == Missing Reference: 'IMAP-UTF-8' is mentioned on line 7044, but not defined == Missing Reference: 'RFC3516' is mentioned on line 7134, 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: 10 errors (**), 0 flaws (~~), 39 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Melnikov, Ed. 3 Internet-Draft Isode Ltd 4 Obsoletes: 3501 (if approved) B. Leiba, Ed. 5 Intended status: Standards Track Futurewei Technologies 6 Expires: January 30, 2021 July 29, 2020 8 Internet Message Access Protocol (IMAP) - Version 4rev2 9 draft-ietf-extra-imap4rev2-17 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 January 30, 2021. 48 Copyright Notice 50 Copyright (c) 2020 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (https://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 This document may contain material from IETF Documents or IETF 64 Contributions published or made publicly available before November 65 10, 2008. The person(s) controlling the copyright in some of this 66 material may not have granted the IETF Trust the right to allow 67 modifications of such material outside the IETF Standards Process. 68 Without obtaining an adequate license from the person(s) controlling 69 the copyright in such materials, this document may not be modified 70 outside the IETF Standards Process, and derivative works of it may 71 not be created outside the IETF Standards Process, except to format 72 it for publication as an RFC or to translate it into languages other 73 than English. 75 Table of Contents 77 1. How to Read This Document . . . . . . . . . . . . . . . . . . 5 78 1.1. Organization of This Document . . . . . . . . . . . . . . 5 79 1.2. Conventions Used in This Document . . . . . . . . . . . . 5 80 1.3. Special Notes to Implementors . . . . . . . . . . . . . . 6 81 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 82 2.1. Link Level . . . . . . . . . . . . . . . . . . . . . . . 7 83 2.2. Commands and Responses . . . . . . . . . . . . . . . . . 7 84 2.2.1. Client Protocol Sender and Server Protocol Receiver . 7 85 2.2.2. Server Protocol Sender and Client Protocol Receiver . 8 86 2.3. Message Attributes . . . . . . . . . . . . . . . . . . . 9 87 2.3.1. Message Numbers . . . . . . . . . . . . . . . . . . . 9 88 2.3.2. Flags Message Attribute . . . . . . . . . . . . . . . 11 89 2.3.3. Internal Date Message Attribute . . . . . . . . . . . 13 90 2.3.4. [RFC-5322] Size Message Attribute . . . . . . . . . . 14 91 2.3.5. Envelope Structure Message Attribute . . . . . . . . 14 92 2.3.6. Body Structure Message Attribute . . . . . . . . . . 14 93 2.4. Message Texts . . . . . . . . . . . . . . . . . . . . . . 14 94 3. State and Flow Diagram . . . . . . . . . . . . . . . . . . . 14 95 3.1. Not Authenticated State . . . . . . . . . . . . . . . . . 14 96 3.2. Authenticated State . . . . . . . . . . . . . . . . . . . 14 97 3.3. Selected State . . . . . . . . . . . . . . . . . . . . . 15 98 3.4. Logout State . . . . . . . . . . . . . . . . . . . . . . 15 99 4. Data Formats . . . . . . . . . . . . . . . . . . . . . . . . 17 100 4.1. Atom . . . . . . . . . . . . . . . . . . . . . . . . . . 17 101 4.1.1. Sequence set and UID set . . . . . . . . . . . . . . 17 102 4.2. Number . . . . . . . . . . . . . . . . . . . . . . . . . 17 103 4.3. String . . . . . . . . . . . . . . . . . . . . . . . . . 17 104 4.3.1. 8-bit and Binary Strings . . . . . . . . . . . . . . 18 105 4.4. Parenthesized List . . . . . . . . . . . . . . . . . . . 19 106 4.5. NIL . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 107 5. Operational Considerations . . . . . . . . . . . . . . . . . 20 108 5.1. Mailbox Naming . . . . . . . . . . . . . . . . . . . . . 20 109 5.1.1. Mailbox Hierarchy Naming . . . . . . . . . . . . . . 21 110 5.1.2. Namespaces . . . . . . . . . . . . . . . . . . . . . 21 111 5.2. Mailbox Size and Message Status Updates . . . . . . . . . 23 112 5.3. Response when no Command in Progress . . . . . . . . . . 23 113 5.4. Autologout Timer . . . . . . . . . . . . . . . . . . . . 23 114 5.5. Multiple Commands in Progress (Command Pipelining) . . . 23 115 6. Client Commands . . . . . . . . . . . . . . . . . . . . . . . 25 116 6.1. Client Commands - Any State . . . . . . . . . . . . . . . 25 117 6.1.1. CAPABILITY Command . . . . . . . . . . . . . . . . . 25 118 6.1.2. NOOP Command . . . . . . . . . . . . . . . . . . . . 26 119 6.1.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . 27 120 6.2. Client Commands - Not Authenticated State . . . . . . . . 27 121 6.2.1. STARTTLS Command . . . . . . . . . . . . . . . . . . 28 122 6.2.2. AUTHENTICATE Command . . . . . . . . . . . . . . . . 29 123 6.2.3. LOGIN Command . . . . . . . . . . . . . . . . . . . . 32 124 6.3. Client Commands - Authenticated State . . . . . . . . . . 33 125 6.3.1. ENABLE Command . . . . . . . . . . . . . . . . . . . 33 126 6.3.2. SELECT Command . . . . . . . . . . . . . . . . . . . 35 127 6.3.3. EXAMINE Command . . . . . . . . . . . . . . . . . . . 37 128 6.3.4. CREATE Command . . . . . . . . . . . . . . . . . . . 38 129 6.3.5. DELETE Command . . . . . . . . . . . . . . . . . . . 39 130 6.3.6. RENAME Command . . . . . . . . . . . . . . . . . . . 41 131 6.3.7. SUBSCRIBE Command . . . . . . . . . . . . . . . . . . 43 132 6.3.8. UNSUBSCRIBE Command . . . . . . . . . . . . . . . . . 44 133 6.3.9. LIST Command . . . . . . . . . . . . . . . . . . . . 44 134 6.3.10. NAMESPACE Command . . . . . . . . . . . . . . . . . . 62 135 6.3.11. STATUS Command . . . . . . . . . . . . . . . . . . . 67 136 6.3.12. APPEND Command . . . . . . . . . . . . . . . . . . . 68 137 6.3.13. IDLE Command . . . . . . . . . . . . . . . . . . . . 71 138 6.4. Client Commands - Selected State . . . . . . . . . . . . 73 139 6.4.1. CLOSE Command . . . . . . . . . . . . . . . . . . . . 73 140 6.4.2. UNSELECT Command . . . . . . . . . . . . . . . . . . 74 141 6.4.3. EXPUNGE Command . . . . . . . . . . . . . . . . . . . 74 142 6.4.4. SEARCH Command . . . . . . . . . . . . . . . . . . . 75 143 6.4.5. FETCH Command . . . . . . . . . . . . . . . . . . . . 87 144 6.4.6. STORE Command . . . . . . . . . . . . . . . . . . . . 91 145 6.4.7. COPY Command . . . . . . . . . . . . . . . . . . . . 93 146 6.4.8. MOVE Command . . . . . . . . . . . . . . . . . . . . 94 147 6.4.9. UID Command . . . . . . . . . . . . . . . . . . . . . 95 148 6.5. Client Commands - Experimental/Expansion . . . . . . . . 97 149 6.5.1. X Command . . . . . . . . . . . . . . . . . . . 97 150 7. Server Responses . . . . . . . . . . . . . . . . . . . . . . 98 151 7.1. Server Responses - Status Responses . . . . . . . . . . . 99 152 7.1.1. OK Response . . . . . . . . . . . . . . . . . . . . . 107 153 7.1.2. NO Response . . . . . . . . . . . . . . . . . . . . . 107 154 7.1.3. BAD Response . . . . . . . . . . . . . . . . . . . . 108 155 7.1.4. PREAUTH Response . . . . . . . . . . . . . . . . . . 108 156 7.1.5. BYE Response . . . . . . . . . . . . . . . . . . . . 108 157 7.2. Server Responses - Server and Mailbox Status . . . . . . 109 158 7.2.1. The ENABLED Response . . . . . . . . . . . . . . . . 109 159 7.2.2. CAPABILITY Response . . . . . . . . . . . . . . . . . 109 160 7.2.3. LIST Response . . . . . . . . . . . . . . . . . . . . 110 161 7.2.4. NAMESPACE Response . . . . . . . . . . . . . . . . . 114 162 7.2.5. STATUS Response . . . . . . . . . . . . . . . . . . . 115 163 7.2.6. ESEARCH Response . . . . . . . . . . . . . . . . . . 115 164 7.2.7. FLAGS Response . . . . . . . . . . . . . . . . . . . 115 165 7.3. Server Responses - Mailbox Size . . . . . . . . . . . . . 116 166 7.3.1. EXISTS Response . . . . . . . . . . . . . . . . . . . 116 167 7.4. Server Responses - Message Status . . . . . . . . . . . . 116 168 7.4.1. EXPUNGE Response . . . . . . . . . . . . . . . . . . 116 169 7.4.2. FETCH Response . . . . . . . . . . . . . . . . . . . 117 170 7.5. Server Responses - Command Continuation Request . . . . . 123 171 8. Sample IMAP4rev2 connection . . . . . . . . . . . . . . . . . 124 172 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 125 173 10. Author's Note . . . . . . . . . . . . . . . . . . . . . . . . 142 174 11. Security Considerations . . . . . . . . . . . . . . . . . . . 142 175 11.1. STARTTLS Security Considerations . . . . . . . . . . . . 142 176 11.2. COPYUID and APPENDUID response codes . . . . . . . . . . 143 177 11.3. LIST command and Other Users' namespace . . . . . . . . 143 178 11.4. Other Security Considerations . . . . . . . . . . . . . 143 179 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 144 180 12.1. Updates to IMAP4 Capabilities registry . . . . . . . . . 145 181 12.2. GSSAPI/SASL service name . . . . . . . . . . . . . . . . 145 182 12.3. LIST Selection Options, LIST Return Options, LIST 183 extended data items . . . . . . . . . . . . . . . . . . 145 184 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 145 185 13.1. Normative References . . . . . . . . . . . . . . . . . . 145 186 13.2. Informative References (related protocols) . . . . . . . 149 187 13.3. Informative References (historical aspects of IMAP and 188 related protocols) . . . . . . . . . . . . . . . . . . . 150 189 Appendix A. Backward compatibility with IMAP4rev1 . . . . . . . 151 190 A.1. Mailbox International Naming Convention for compatibility 191 with IMAP4rev1 . . . . . . . . . . . . . . . . . . . . . 152 193 Appendix B. Backward compatibility with BINARY extension . . . . 153 194 Appendix C. Backward compatibility with LIST-EXTENDED extension 153 195 Appendix D. Changes from RFC 3501 / IMAP4rev1 . . . . . . . . . 154 196 Appendix E. Acknowledgement . . . . . . . . . . . . . . . . . . 156 197 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 198 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 162 200 1. How to Read This Document 202 1.1. Organization of This Document 204 This document is written from the point of view of the implementor of 205 an IMAP4rev2 client or server. Beyond the protocol overview in 206 section 2, it is not optimized for someone trying to understand the 207 operation of the protocol. The material in sections 3 through 5 208 provides the general context and definitions with which IMAP4rev2 209 operates. 211 Sections 6, 7, and 9 describe the IMAP commands, responses, and 212 syntax, respectively. The relationships among these are such that it 213 is almost impossible to understand any of them separately. In 214 particular, do not attempt to deduce command syntax from the command 215 section alone; instead refer to the Formal Syntax section. 217 1.2. Conventions Used in This Document 219 "Conventions" are basic principles or procedures. Document 220 conventions are noted in this section. 222 In examples, "C:" and "S:" indicate lines sent by the client and 223 server respectively. 225 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 226 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 227 "OPTIONAL" in this document are to be interpreted as described in BCP 228 14 [RFC2119] [RFC8174] when, and only when, they appear in all 229 capitals, as shown here. 231 The word "can" (not "may") is used to refer to a possible 232 circumstance or situation, as opposed to an optional facility of the 233 protocol. 235 "User" is used to refer to a human user, whereas "client" refers to 236 the software being run by the user. 238 "Connection" refers to the entire sequence of client/server 239 interaction from the initial establishment of the network connection 240 until its termination. 242 "Session" refers to the sequence of client/server interaction from 243 the time that a mailbox is selected (SELECT or EXAMINE command) until 244 the time that selection ends (SELECT or EXAMINE of another mailbox, 245 CLOSE command, UNSELECT command, or connection termination). 247 Characters are 8-bit UTF-8 (of which 7-bit US-ASCII is a subset) 248 unless otherwise specified. Other character sets are indicated using 249 a "CHARSET", as described in [MIME-IMT] and defined in [CHARSET]. 250 CHARSETs have important additional semantics in addition to defining 251 character set; refer to these documents for more detail. 253 There are several protocol conventions in IMAP. These refer to 254 aspects of the specification which are not strictly part of the IMAP 255 protocol, but reflect generally-accepted practice. Implementations 256 need to be aware of these conventions, and avoid conflicts whether or 257 not they implement the convention. For example, "&" may not be used 258 as a hierarchy delimiter since it conflicts with the Mailbox 259 International Naming Convention, and other uses of "&" in mailbox 260 names are impacted as well. 262 1.3. Special Notes to Implementors 264 Implementors of the IMAP protocol are strongly encouraged to read the 265 IMAP implementation recommendations document [IMAP-IMPLEMENTATION] in 266 conjunction with this document, to help understand the intricacies of 267 this protocol and how best to build an interoperable product. 269 IMAP4rev2 is designed to be upwards compatible from the [IMAP2] and 270 unpublished IMAP2bis protocols. IMAP4rev2 is largely compatible with 271 the IMAP4rev1 protocol described in RFC 3501 and the IMAP4 protocol 272 described in RFC 1730; the exception being in certain facilities 273 added in RFC 1730 that proved problematic and were subsequently 274 removed. In the course of the evolution of IMAP4rev2, some aspects 275 in the earlier protocols have become obsolete. Obsolete commands, 276 responses, and data formats which an IMAP4rev2 implementation can 277 encounter when used with an earlier implementation are described in 278 Appendix D and [IMAP-OBSOLETE]. 280 Other compatibility issues with IMAP2bis, the most common variant of 281 the earlier protocol, are discussed in [IMAP-COMPAT]. A full 282 discussion of compatibility issues with rare (and presumed extinct) 283 variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is 284 primarily of historical interest. 286 IMAP was originally developed for the older [RFC-822] standard, and 287 as a consequence several fetch items in IMAP incorporate "RFC822" in 288 their name. In all cases, "RFC822" should be interpreted as a 289 reference to the updated [RFC-5322] standard. 291 2. Protocol Overview 293 2.1. Link Level 295 The IMAP4rev2 protocol assumes a reliable data stream such as that 296 provided by TCP. When TCP is used, an IMAP4rev2 server listens on 297 port 143 or port 993 (IMAP-over-TLS). 299 2.2. Commands and Responses 301 An IMAP4rev2 connection consists of the establishment of a client/ 302 server network connection, an initial greeting from the server, and 303 client/server interactions. These client/server interactions consist 304 of a client command, server data, and a server completion result 305 response. 307 All interactions transmitted by client and server are in the form of 308 lines, that is, strings that end with a CRLF. The protocol receiver 309 of an IMAP4rev2 client or server is either reading a line, or is 310 reading a sequence of octets with a known count followed by a line. 312 2.2.1. Client Protocol Sender and Server Protocol Receiver 314 The client command begins an operation. Each client command is 315 prefixed with an identifier (typically a short alphanumeric string, 316 e.g., A0001, A0002, etc.) called a "tag". A different tag is 317 generated by the client for each command. (More formally: the client 318 SHOULD generate a unique tag for every command, but a server MUST 319 accept tag reuse.) 321 Clients MUST follow the syntax outlined in this specification 322 strictly. It is a syntax error to send a command with missing or 323 extraneous spaces or arguments. 325 There are two cases in which a line from the client does not 326 represent a complete command. In one case, a command argument is 327 quoted with an octet count (see the description of literal in String 328 under Data Formats); in the other case, the command arguments require 329 server feedback (see the AUTHENTICATE command). In either case, the 330 server sends a command continuation request response if it is ready 331 for the octets (if appropriate) and the remainder of the command. 332 This response is prefixed with the token "+". 334 Note: If instead, the server detected an error in the command, it 335 sends a BAD completion response with a tag matching the command 336 (as described below) to reject the command and prevent the client 337 from sending any more of the command. 339 It is also possible for the server to send a completion response 340 for some other command (if multiple commands are in progress), or 341 untagged data. In either case, the command continuation request 342 is still pending; the client takes the appropriate action for the 343 response, and reads another response from the server. In all 344 cases, the client MUST send a complete command (including 345 receiving all command continuation request responses and command 346 continuations for the command) before initiating a new command. 348 The protocol receiver of an IMAP4rev2 server reads a command line 349 from the client, parses the command and its arguments, and transmits 350 server data and a server command completion result response. 352 2.2.2. Server Protocol Sender and Client Protocol Receiver 354 Data transmitted by the server to the client and status responses 355 that do not indicate command completion are prefixed with the token 356 "*", and are called untagged responses. 358 Server data MAY be sent as a result of a client command, or MAY be 359 sent unilaterally by the server. There is no syntactic difference 360 between server data that resulted from a specific command and server 361 data that were sent unilaterally. 363 The server completion result response indicates the success or 364 failure of the operation. It is tagged with the same tag as the 365 client command which began the operation. Thus, if more than one 366 command is in progress, the tag in a server completion response 367 identifies the command to which the response applies. There are 368 three possible server completion responses: OK (indicating success), 369 NO (indicating failure), or BAD (indicating a protocol error such as 370 unrecognized command or command syntax error). 372 Servers SHOULD enforce the syntax outlined in this specification 373 strictly. Any client command with a protocol syntax error, including 374 (but not limited to) missing or extraneous spaces or arguments, 375 SHOULD be rejected, and the client given a BAD server completion 376 response. 378 The protocol receiver of an IMAP4rev2 client reads a response line 379 from the server. It then takes action on the response based upon the 380 first token of the response, which can be a tag, a "*", or a "+". 382 A client MUST be prepared to accept any server response at all times. 383 This includes server data that was not requested. Server data SHOULD 384 be recorded, so that the client can reference its recorded copy 385 rather than sending a command to the server to request the data. In 386 the case of certain server data, the data MUST be recorded. 388 This topic is discussed in greater detail in the Server Responses 389 section. 391 2.3. Message Attributes 393 In addition to message text, each message has several attributes 394 associated with it. These attributes can be retrieved individually 395 or in conjunction with other attributes or message texts. 397 2.3.1. Message Numbers 399 Messages in IMAP4rev2 are accessed by one of two numbers; the unique 400 identifier or the message sequence number. 402 2.3.1.1. Unique Identifier (UID) Message Attribute 404 An unsigned non-zero 32-bit value assigned to each message, which 405 when used with the unique identifier validity value (see below) forms 406 a 64-bit value that MUST NOT refer to any other message in the 407 mailbox or any subsequent mailbox with the same name forever. Unique 408 identifiers are assigned in a strictly ascending fashion in the 409 mailbox; as each message is added to the mailbox it is assigned a 410 higher UID than the message(s) which were added previously. Unlike 411 message sequence numbers, unique identifiers are not necessarily 412 contiguous. 414 The unique identifier of a message MUST NOT change during the 415 session, and SHOULD NOT change between sessions. Any change of 416 unique identifiers between sessions MUST be detectable using the 417 UIDVALIDITY mechanism discussed below. Persistent unique identifiers 418 are required for a client to resynchronize its state from a previous 419 session with the server (e.g., disconnected or offline access clients 420 [IMAP-MODEL]); this is discussed further in [IMAP-DISC]. 422 Associated with every mailbox are two 32-bit unsigned non-zero values 423 which aid in unique identifier handling: the next unique identifier 424 value (UIDNEXT) and the unique identifier validity value 425 (UIDVALIDITY). 427 The next unique identifier value is the predicted value that will be 428 assigned to a new message in the mailbox. Unless the unique 429 identifier validity also changes (see below), the next unique 430 identifier value MUST have the following two characteristics. First, 431 the next unique identifier value MUST NOT change unless new messages 432 are added to the mailbox; and second, the next unique identifier 433 value MUST change whenever new messages are added to the mailbox, 434 even if those new messages are subsequently expunged. 436 Note: The next unique identifier value is intended to provide a 437 means for a client to determine whether any messages have been 438 delivered to the mailbox since the previous time it checked this 439 value. It is not intended to provide any guarantee that any 440 message will have this unique identifier. A client can only 441 assume, at the time that it obtains the next unique identifier 442 value, that messages arriving after that time will have a UID 443 greater than or equal to that value. 445 The unique identifier validity value is sent in a UIDVALIDITY 446 response code in an OK untagged response at mailbox selection time. 447 If unique identifiers from an earlier session fail to persist in this 448 session, the unique identifier validity value MUST be greater than 449 the one used in the earlier session. A good UIDVALIDITY value to use 450 is a 32-bit representation of the current date/time when the value is 451 assigned: this ensures that the value is unique and always increases. 452 Another possible alternative is a global counter that gets 453 incremented every time a mailbox is created. 455 Note: Ideally, unique identifiers SHOULD persist at all times. 456 Although this specification recognizes that failure to persist can 457 be unavoidable in certain server environments, it STRONGLY 458 ENCOURAGES message store implementation techniques that avoid this 459 problem. For example: 461 1. Unique identifiers MUST be strictly ascending in the mailbox 462 at all times. If the physical message store is re-ordered by 463 a non-IMAP agent, this requires that the unique identifiers in 464 the mailbox be regenerated, since the former unique 465 identifiers are no longer strictly ascending as a result of 466 the re-ordering. 468 2. If the message store has no mechanism to store unique 469 identifiers, it must regenerate unique identifiers at each 470 session, and each session must have a unique UIDVALIDITY 471 value. 473 3. If the mailbox is deleted/renamed and a new mailbox with the 474 same name is created at a later date, the server must either 475 keep track of unique identifiers from the previous instance of 476 the mailbox, or it must assign a new UIDVALIDITY value to the 477 new instance of the mailbox. 479 4. The combination of mailbox name, UIDVALIDITY, and UID must 480 refer to a single immutable (or expunged) message on that 481 server forever. In particular, the internal date, [RFC-5322] 482 size, envelope, body structure, and message texts (all 483 BODY[...] fetch data items) must never change. This does not 484 include message numbers, nor does it include attributes that 485 can be set by a STORE command (e.g., FLAGS). When a message 486 is expunged, its UID MUST NOT be reused under the same 487 UIDVALIDITY value. 489 2.3.1.2. Message Sequence Number Message Attribute 491 A relative position from 1 to the number of messages in the mailbox. 492 This position MUST be ordered by ascending unique identifier. As 493 each new message is added, it is assigned a message sequence number 494 that is 1 higher than the number of messages in the mailbox before 495 that new message was added. 497 Message sequence numbers can be reassigned during the session. For 498 example, when a message is permanently removed (expunged) from the 499 mailbox, the message sequence number for all subsequent messages is 500 decremented. The number of messages in the mailbox is also 501 decremented. Similarly, a new message can be assigned a message 502 sequence number that was once held by some other message prior to an 503 expunge. 505 In addition to accessing messages by relative position in the 506 mailbox, message sequence numbers can be used in mathematical 507 calculations. For example, if an untagged "11 EXISTS" is received, 508 and previously an untagged "8 EXISTS" was received, three new 509 messages have arrived with message sequence numbers of 9, 10, and 11. 510 Another example, if message 287 in a 523 message mailbox has UID 511 12345, there are exactly 286 messages which have lesser UIDs and 236 512 messages which have greater UIDs. 514 2.3.2. Flags Message Attribute 516 A list of zero or more named tokens associated with the message. A 517 flag is set by its addition to this list, and is cleared by its 518 removal. There are two types of flags in IMAP4rev2. A flag of 519 either type can be permanent or session-only. 521 A system flag is a flag name that is pre-defined in this 522 specification and begin with "\". Certain system flags (\Deleted and 523 \Seen) have special semantics described elsewhere in this document. 524 The currently-defined system flags are: 526 \Seen Message has been read 528 \Answered Message has been answered 530 \Flagged Message is "flagged" for urgent/special attention 531 \Deleted Message is "deleted" for removal by later EXPUNGE 533 \Draft Message has not completed composition (marked as a draft). 535 \Recent This flag was in used in IMAP4rev1 and is now deprecated. 537 A keyword is defined by the server implementation. Keywords do not 538 begin with "\". Servers MAY permit the client to define new keywords 539 in the mailbox (see the description of the PERMANENTFLAGS response 540 code for more information). Some keywords that start with "$" are 541 also defined in this specification. 543 This document defines several keywords that were not originally 544 defined in RFC 3501, but which were found to be useful by client 545 implementations. These keywords SHOULD be supported (i.e. allowed in 546 SEARCH, allowed and preserved in APPEND, COPY, MOVE commands) by 547 server implementations: 549 $Forwarded Message has been forwarded to another email address, 550 embedded within or attached to a new message. An email client 551 sets this keyword when it successfully forwards the message to 552 another email address. Typical usage of this keyword is to show a 553 different (or additional) icon for a message that has been 554 forwarded. Once set, the flag SHOULD NOT be cleared. 556 $MDNSent Message Disposition Notification [RFC8098] was generated 557 and sent for this message. See [RFC3503] for more details on how 558 this keyword is used. 560 $Junk The user (or a delivery agent on behalf of the user) may 561 choose to mark a message as definitely containing junk ($Junk; see 562 also the related keyword $NotJunk). The $Junk keyword can be used 563 to mark (and potentially move/delete messages later), group or 564 hide undesirable messages. See [IMAP-KEYWORDS-REG] for more 565 information. 567 $NotJunk The user (or a delivery agent on behalf of the user) may 568 choose to mark a message as definitely not containing junk 569 ($NotJunk; see also the related keyword $Junk). The $NotJunk 570 keyword can be used to mark, group or show messages that the user 571 wants to see. See [IMAP-KEYWORDS-REG] for more information. 573 $Phishing The $Phishing keyword can be used by a delivery agent to 574 mark a message as highly likely to be a phishing email. An email 575 that's determined to be a phishing email by the delivery agent 576 should also be considered a junk email and have the appropriate 577 junk filtering applied, including setting the $Junk flag and 578 placing in the \Junk special-use mailbox (see Section 7.2.3) if 579 available. 580 If both the $Phishing flag and the $Junk flag are set, the user 581 agent should display an additional warning message to the user. 582 User agents should not use the term "phishing" in their warning 583 message as most users do not understand this term. Phrasing of 584 the form "this message may be trying to steal your personal 585 information" is recommended. Additionally the user agent may 586 display a warning when clicking on any hyperlinks within the 587 message. 588 The requirement for both $Phishing and $Junk to be set before a 589 user agent displays a warning is for better backwards 590 compatibility with existing clients that understand the $Junk flag 591 but not the $Phishing flag. This so that when an unextended 592 client removes the $Junk flag, an extended client will also show 593 the correct state. See [IMAP-KEYWORDS-REG] for more information. 595 $Junk and $NotJunk are mutually exclusive. If more than one of them 596 is set for a message, the client MUST treat this as if none of them 597 is set and SHOULD unset both of them on the IMAP server. 599 Other registered keywords can be found in the "IMAP and JMAP 600 Keywords" registry [IMAP-KEYWORDS-REG]. New keywords SHOULD be 601 registered in this registry using the procedure specified in 602 [RFC5788]. 604 A flag can be permanent or session-only on a per-flag basis. 605 Permanent flags are those which the client can add or remove from the 606 message flags permanently; that is, concurrent and subsequent 607 sessions will see any change in permanent flags. Changes to session 608 flags are valid only in that session. 610 2.3.3. Internal Date Message Attribute 612 The internal date and time of the message on the server. This is not 613 the date and time in the [RFC-5322] header, but rather a date and 614 time which reflects when the message was received. In the case of 615 messages delivered via [SMTP], this SHOULD be the date and time of 616 final delivery of the message as defined by [SMTP]. In the case of 617 messages delivered by the IMAP4rev2 COPY or MOVE command, this SHOULD 618 be the internal date and time of the source message. In the case of 619 messages delivered by the IMAP4rev2 APPEND command, this SHOULD be 620 the date and time as specified in the APPEND command description. 621 All other cases are implementation defined. 623 2.3.4. [RFC-5322] Size Message Attribute 625 The number of octets in the message, as expressed in [RFC-5322] 626 format. 628 2.3.5. Envelope Structure Message Attribute 630 A parsed representation of the [RFC-5322] header of the message. 631 Note that the IMAP Envelope structure is not the same as an [SMTP] 632 envelope. 634 2.3.6. Body Structure Message Attribute 636 A parsed representation of the [MIME-IMB] body structure information 637 of the message. 639 2.4. Message Texts 641 In addition to being able to fetch the full [RFC-5322] text of a 642 message, IMAP4rev2 permits the fetching of portions of the full 643 message text. Specifically, it is possible to fetch the [RFC-5322] 644 message header, [RFC-5322] message body, a [MIME-IMB] body part, or a 645 [MIME-IMB] header. 647 3. State and Flow Diagram 649 Once the connection between client and server is established, an 650 IMAP4rev2 connection is in one of four states. The initial state is 651 identified in the server greeting. Most commands are only valid in 652 certain states. It is a protocol error for the client to attempt a 653 command while the connection is in an inappropriate state, and the 654 server will respond with a BAD or NO (depending upon server 655 implementation) command completion result. 657 3.1. Not Authenticated State 659 In the not authenticated state, the client MUST supply authentication 660 credentials before most commands will be permitted. This state is 661 entered when a connection starts unless the connection has been pre- 662 authenticated. 664 3.2. Authenticated State 666 In the authenticated state, the client is authenticated and MUST 667 select a mailbox to access before commands that affect messages will 668 be permitted. This state is entered when a pre-authenticated 669 connection starts, when acceptable authentication credentials have 670 been provided, after an error in selecting a mailbox, or after a 671 successful CLOSE command. 673 3.3. Selected State 675 In a selected state, a mailbox has been selected to access. This 676 state is entered when a mailbox has been successfully selected. 678 3.4. Logout State 680 In the logout state, the connection is being terminated. This state 681 can be entered as a result of a client request (via the LOGOUT 682 command) or by unilateral action on the part of either the client or 683 server. 685 If the client requests the logout state, the server MUST send an 686 untagged BYE response and a tagged OK response to the LOGOUT command 687 before the server closes the connection; and the client MUST read the 688 tagged OK response to the LOGOUT command before the client closes the 689 connection. 691 A server SHOULD NOT unilaterally close the connection without sending 692 an untagged BYE response that contains the reason for having done so. 693 A client SHOULD NOT unilaterally close the connection, and instead 694 SHOULD issue a LOGOUT command. If the server detects that the client 695 has unilaterally closed the connection, the server MAY omit the 696 untagged BYE response and simply close its connection. 698 +----------------------+ 699 |connection established| 700 +----------------------+ 701 || 702 \/ 703 +--------------------------------------+ 704 | server greeting | 705 +--------------------------------------+ 706 || (1) || (2) || (3) 707 \/ || || 708 +-----------------+ || || 709 |Not Authenticated| || || 710 +-----------------+ || || 711 || (7) || (4) || || 712 || \/ \/ || 713 || +----------------+ || 714 || | Authenticated |<=++ || 715 || +----------------+ || || 716 || || (7) || (5) || (6) || 717 || || \/ || || 718 || || +--------+ || || 719 || || |Selected|==++ || 720 || || +--------+ || 721 || || || (7) || 722 \/ \/ \/ \/ 723 +--------------------------------------+ 724 | Logout | 725 +--------------------------------------+ 726 || 727 \/ 728 +-------------------------------+ 729 |both sides close the connection| 730 +-------------------------------+ 732 (1) connection without pre-authentication (OK greeting) 733 (2) pre-authenticated connection (PREAUTH greeting) 734 (3) rejected connection (BYE greeting) 735 (4) successful LOGIN or AUTHENTICATE command 736 (5) successful SELECT or EXAMINE command 737 (6) CLOSE command, unsolicited CLOSED response code or 738 failed SELECT or EXAMINE command 739 (7) LOGOUT command, server shutdown, or connection closed 741 4. Data Formats 743 IMAP4rev2 uses textual commands and responses. Data in IMAP4rev2 can 744 be in one of several forms: atom, number, string, parenthesized list, 745 or NIL. Note that a particular data item may take more than one 746 form; for example, a data item defined as using "astring" syntax may 747 be either an atom or a string. 749 4.1. Atom 751 An atom consists of one or more non-special characters. 753 4.1.1. Sequence set and UID set 755 A set of messages can be referenced by a sequence set containing 756 either message sequence numbers or unique identifiers. See Section 9 757 for details. Sequence sets can contain ranges (e.g. "5:50"), an 758 enumeration of specific message/UID numbers, a special symbol "*", or 759 a combination of the above. 761 A "UID set" is similar to the sequence set of unique identifiers; 762 however, the "*" value for a sequence number is not permitted. 764 4.2. Number 766 A number consists of one or more digit characters, and represents a 767 numeric value. 769 4.3. String 771 A string is in one of three forms: synchonizing literal, non- 772 synchronizing literal or quoted string. The synchronizing literal 773 form is the general form of string. The non-synchronizing literal 774 form is also the general form, but has length limitation. The quoted 775 string form is an alternative that avoids the overhead of processing 776 a literal at the cost of limitations of characters which may be used. 778 When the distinction between synchronizing and non-synchronizing 779 literals is not important, this document just uses the term 780 "literal". 782 A synchronizing literal is a sequence of zero or more octets 783 (including CR and LF), prefix-quoted with an octet count in the form 784 of an open brace ("{"), the number of octets, close brace ("}"), and 785 CRLF. In the case of synchronizing literals transmitted from server 786 to client, the CRLF is immediately followed by the octet data. In 787 the case of synchronizing literals transmitted from client to server, 788 the client MUST wait to receive a command continuation request 789 (described later in this document) before sending the octet data (and 790 the remainder of the command). 792 The non-synchronizing literal is an alternate form of synchronizing 793 literal, and it may appear in communication from client to server 794 instead of the synchonizing form of literal. The non-synchronizing 795 literal form MUST NOT be sent from server to client. The non- 796 synchronizing literal is distinguished from the synchronizing literal 797 by having a plus ("+") between the octet count and the closing brace 798 ("}"). The server does not generate a command continuation request 799 in response to a non-synchronizing literal, and clients are not 800 required to wait before sending the octets of a non- synchronizing 801 literal. Non-synchronizing literals MUST NOT be larger than 4096 802 octets. Any literal larger than 4096 bytes MUST be sent as a 803 synchronizing literal. (Non-synchronizing literals defined in this 804 document are the same as non-synchronizing literals defined by the 805 LITERAL- extension from [RFC7888]. See that document for details on 806 how to handle invalid non-synchronizing literals longer than 4096 807 octets and for interaction with other IMAP extensions.) 809 A quoted string is a sequence of zero or more Unicode characters, 810 excluding CR and LF, encoded in UTF-8, with double quote (<">) 811 characters at each end. 813 The empty string is represented as "" (a quoted string with zero 814 characters between double quotes), as {0} followed by CRLF (a 815 synchronizing literal with an octet count of 0) or as {0+} followed 816 by CRLF (a non-synchronizing literal with an octet count of 0). 818 Note: Even if the octet count is 0, a client transmitting a 819 synchronizing literal MUST wait to receive a command continuation 820 request. 822 4.3.1. 8-bit and Binary Strings 824 8-bit textual and binary mail is supported through the use of a 825 [MIME-IMB] content transfer encoding. IMAP4rev2 implementations MAY 826 transmit 8-bit or multi-octet characters in literals, but SHOULD do 827 so only when the [CHARSET] is identified. 829 IMAP4rev2 is compatible with [I18N-HDRS]. As a result, the 830 identified charset for header-field values with 8-bit content is 831 UTF-8 [UTF-8]. IMAP4rev2 implementations MUST accept and MAY 832 transmit [UTF-8] text in quoted-strings as long as the string does 833 not contain NUL, CR, or LF. This differs from IMAP4rev1 834 implementations. 836 Although a BINARY content transfer encoding is defined, unencoded 837 binary strings are not permitted, unless returned in a in 838 response to BINARY.PEEK[]<> or 839 BINARY[]<> FETCH data item. A "binary 840 string" is any string with NUL characters. A string with an 841 excessive amount of CTL characters MAY also be considered to be 842 binary. Unless returned in response to BINARY.PEEK[...]/BINARY[...] 843 FETCH, client and server implementations MUST encode binary data into 844 a textual form, such as BASE64, before transmitting the data. 846 4.4. Parenthesized List 848 Data structures are represented as a "parenthesized list"; a sequence 849 of data items, delimited by space, and bounded at each end by 850 parentheses. A parenthesized list can contain other parenthesized 851 lists, using multiple levels of parentheses to indicate nesting. 853 The empty list is represented as () -- a parenthesized list with no 854 members. 856 4.5. NIL 858 The special form "NIL" represents the non-existence of a particular 859 data item that is represented as a string or parenthesized list, as 860 distinct from the empty string "" or the empty parenthesized list (). 862 Note: NIL is never used for any data item which takes the form of 863 an atom. For example, a mailbox name of "NIL" is a mailbox named 864 NIL as opposed to a non-existent mailbox name. This is because 865 mailbox uses "astring" syntax which is an atom or a string. 866 Conversely, an addr-name of NIL is a non-existent personal name, 867 because addr-name uses "nstring" syntax which is NIL or a string, 868 but never an atom. 870 Examples: 872 The following LIST response: 874 * LIST () "/" NIL 876 is equivalent to: 877 * LIST () "/" "NIL" 879 as LIST response ABNF is using astring for mailbox name. 881 However, the following response 883 * FETCH 1 (BODY[1] NIL) 885 is not equivalent to: 886 * FETCH 1 (BODY[1] "NIL") 887 The former means absence of the body part, while the latter 888 means that it contains literal sequence of characters "NIL". 890 5. Operational Considerations 892 The following rules are listed here to ensure that all IMAP4rev2 893 implementations interoperate properly. 895 5.1. Mailbox Naming 897 In IMAP4rev2, Mailbox names are encoded in Net-Unicode [NET-UNICODE] 898 (this differs from IMAP4rev1). Client implementations MAY attempt to 899 create Net-Unicode mailbox names, and MUST interpret any 8-bit 900 mailbox names returned by LIST as [NET-UNICODE]. Server 901 implementations MUST prohibit the creation of 8-bit mailbox names 902 that do not comply with Net-Unicode. However, servers MAY accept a 903 de-normalized UTF-8 mailbox name and convert it to Unicode 904 normalization form "NFC" (as per Net-Unicode requirements) prior to 905 mailbox creation. Servers that choose to accept such de-normalized 906 UTF-8 mailbox names MUST accept them in all IMAP commands that have a 907 mailbox name parameter. In particular SELECT must open the 908 same mailbox that was successfully created with CREATE , even 909 if is a de-normalized UTF-8 mailbox name. 911 The case-insensitive mailbox name INBOX is a special name reserved to 912 mean "the primary mailbox for this user on this server". (Note that 913 this special name may not exist on some servers for some users, for 914 example if the user has no access to personal namespace.) The 915 interpretation of all other names is implementation-dependent. 917 In particular, this specification takes no position on case 918 sensitivity in non-INBOX mailbox names. Some server implementations 919 are fully case-sensitive in ASCII range; others preserve case of a 920 newly-created name but otherwise are case-insensitive; and yet others 921 coerce names to a particular case. Client implementations must be 922 able to interact with any of these. 924 There are certain client considerations when creating a new mailbox 925 name: 927 1. Any character which is one of the atom-specials (see the Formal 928 Syntax) will require that the mailbox name be represented as a 929 quoted string or literal. 931 2. CTL and other non-graphic characters are difficult to represent 932 in a user interface and are best avoided. Servers MAY refuse to 933 create mailbox names containing Unicode CTL characters. 935 3. Although the list-wildcard characters ("%" and "*") are valid in 936 a mailbox name, it is difficult to use such mailbox names with 937 the LIST command due to the conflict with wildcard 938 interpretation. 940 4. Usually, a character (determined by the server implementation) is 941 reserved to delimit levels of hierarchy. 943 5. Two characters, "#" and "&", have meanings by convention, and 944 should be avoided except when used in that convention. See 945 Section 5.1.2.1 and Appendix A.1 respectively. 947 5.1.1. Mailbox Hierarchy Naming 949 If it is desired to export hierarchical mailbox names, mailbox names 950 MUST be left-to-right hierarchical using a single character to 951 separate levels of hierarchy. The same hierarchy separator character 952 is used for all levels of hierarchy within a single name. 954 5.1.2. Namespaces 956 Personal Namespace: A namespace that the server considers within the 957 personal scope of the authenticated user on a particular connection. 958 Typically, only the authenticated user has access to mailboxes in 959 their Personal Namespace. It is the part of the namespace that 960 belongs to the user that is allocated for mailboxes. If an INBOX 961 exists for a user, it MUST appear within the user's personal 962 namespace. In the typical case, there SHOULD be only one Personal 963 Namespace on a server. 965 Other Users' Namespace: A namespace that consists of mailboxes from 966 the Personal Namespaces of other users. To access mailboxes in the 967 Other Users' Namespace, the currently authenticated user MUST be 968 explicitly granted access rights. For example, it is common for a 969 manager to grant to their secretary access rights to their mailbox. 970 In the typical case, there SHOULD be only one Other Users' Namespace 971 on a server. 973 Shared Namespace: A namespace that consists of mailboxes that are 974 intended to be shared amongst users and do not exist within a user's 975 Personal Namespace. 977 The namespaces a server uses MAY differ on a per-user basis. 979 5.1.2.1. Historic Mailbox Namespace Naming Convention 981 By convention, the first hierarchical element of any mailbox name 982 which begins with "#" identifies the "namespace" of the remainder of 983 the name. This makes it possible to disambiguate between different 984 types of mailbox stores, each of which have their own namespaces. 986 For example, implementations which offer access to USENET 987 newsgroups MAY use the "#news" namespace to partition the USENET 988 newsgroup namespace from that of other mailboxes. Thus, the 989 comp.mail.misc newsgroup would have a mailbox name of 990 "#news.comp.mail.misc", and the name "comp.mail.misc" can refer to 991 a different object (e.g., a user's private mailbox). 993 Namespaces that include the "#" character are not IMAP URL [IMAP-URL] 994 friendly requiring the "#" character to be represented as %23 when 995 within URLs. As such, server implementers MAY instead consider using 996 namespace prefixes that do not contain the "#" character. 998 5.1.2.2. Common namespace models 1000 Previous version of this protocol does not define a default server 1001 namespace. Two common namespace models have evolved: 1003 The "Personal Mailbox" model, in which the default namespace that is 1004 presented consists of only the user's personal mailboxes. To access 1005 shared mailboxes, the user must use an escape mechanism to reach 1006 another namespace. 1008 The "Complete Hierarchy" model, in which the default namespace that 1009 is presented includes the user's personal mailboxes along with any 1010 other mailboxes they have access to. 1012 5.2. Mailbox Size and Message Status Updates 1014 At any time, a server can send data that the client did not request. 1015 Sometimes, such behavior is REQUIRED. For example, agents other than 1016 the server MAY add messages to the mailbox (e.g., new message 1017 delivery), change the flags of the messages in the mailbox (e.g., 1018 simultaneous access to the same mailbox by multiple agents), or even 1019 remove messages from the mailbox. A server MUST send mailbox size 1020 updates automatically if a mailbox size change is observed during the 1021 processing of a command. A server SHOULD send message flag updates 1022 automatically, without requiring the client to request such updates 1023 explicitly. 1025 Special rules exist for server notification of a client about the 1026 removal of messages to prevent synchronization errors; see the 1027 description of the EXPUNGE response for more detail. In particular, 1028 it is NOT permitted to send an EXISTS response that would reduce the 1029 number of messages in the mailbox; only the EXPUNGE response can do 1030 this. 1032 Regardless of what implementation decisions a client makes on 1033 remembering data from the server, a client implementation MUST record 1034 mailbox size updates. It MUST NOT assume that any command after the 1035 initial mailbox selection will return the size of the mailbox. 1037 5.3. Response when no Command in Progress 1039 Server implementations are permitted to send an untagged response 1040 (except for EXPUNGE) while there is no command in progress. Server 1041 implementations that send such responses MUST deal with flow control 1042 considerations. Specifically, they MUST either (1) verify that the 1043 size of the data does not exceed the underlying transport's available 1044 window size, or (2) use non-blocking writes. 1046 5.4. Autologout Timer 1048 If a server has an inactivity autologout timer that applies to 1049 sessions after authentication, the duration of that timer MUST be at 1050 least 30 minutes. The receipt of ANY command from the client during 1051 that interval SHOULD suffice to reset the autologout timer. 1053 5.5. Multiple Commands in Progress (Command Pipelining) 1055 The client MAY send another command without waiting for the 1056 completion result response of a command, subject to ambiguity rules 1057 (see below) and flow control constraints on the underlying data 1058 stream. Similarly, a server MAY begin processing another command 1059 before processing the current command to completion, subject to 1060 ambiguity rules. However, any command continuation request responses 1061 and command continuations MUST be negotiated before any subsequent 1062 command is initiated. 1064 The exception is if an ambiguity would result because of a command 1065 that would affect the results of other commands. If the server 1066 detects a possible ambiguity, it MUST execute commands to completion 1067 in the order given by the client. 1069 The most obvious example of ambiguity is when a command would affect 1070 the results of another command, e.g., a FETCH of a message's flags 1071 and a STORE of that same message's flags. 1073 A non-obvious ambiguity occurs with commands that permit an untagged 1074 EXPUNGE response (commands other than FETCH, STORE, and SEARCH), 1075 since an untagged EXPUNGE response can invalidate sequence numbers in 1076 a subsequent command. This is not a problem for FETCH, STORE, or 1077 SEARCH commands because servers are prohibited from sending EXPUNGE 1078 responses while any of those commands are in progress. Therefore, if 1079 the client sends any command other than FETCH, STORE, or SEARCH, it 1080 MUST wait for the completion result response before sending a command 1081 with message sequence numbers. 1083 Note: EXPUNGE responses are permitted while UID FETCH, UID STORE, 1084 and UID SEARCH are in progress. If the client sends a UID 1085 command, it MUST wait for a completion result response before 1086 sending a command which uses message sequence numbers (this may 1087 include UID SEARCH). Any message sequence numbers in an argument 1088 to UID SEARCH are associated with messages prior to the effect of 1089 any untagged EXPUNGE returned by the UID SEARCH. 1091 For example, the following non-waiting command sequences are invalid: 1093 FETCH + NOOP + STORE 1095 STORE + COPY + FETCH 1097 COPY + COPY 1099 The following are examples of valid non-waiting command sequences: 1101 FETCH + STORE + SEARCH + NOOP 1103 STORE + COPY + EXPUNGE 1105 UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting 1106 command sequence, depending upon whether or not the second UID 1107 SEARCH contains message sequence numbers. 1109 Use of SEARCH result variable (see Section 6.4.4.1) creates direct 1110 dependency between two commands. See Section 6.4.4.2 for more 1111 considerations about pipelining such dependent commands. 1113 6. Client Commands 1115 IMAP4rev2 commands are described in this section. Commands are 1116 organized by the state in which the command is permitted. Commands 1117 which are permitted in multiple states are listed in the minimum 1118 permitted state (for example, commands valid in authenticated and 1119 selected state are listed in the authenticated state commands). 1121 Command arguments, identified by "Arguments:" in the command 1122 descriptions below, are described by function, not by syntax. The 1123 precise syntax of command arguments is described in the Formal Syntax 1124 (Section 9). 1126 Some commands cause specific server responses to be returned; these 1127 are identified by "Responses:" in the command descriptions below. 1128 See the response descriptions in the Responses section for 1129 information on these responses, and the Formal Syntax section for the 1130 precise syntax of these responses. It is possible for server data to 1131 be transmitted as a result of any command. Thus, commands that do 1132 not specifically require server data specify "no specific responses 1133 for this command" instead of "none". 1135 The "Result:" in the command description refers to the possible 1136 tagged status responses to a command, and any special interpretation 1137 of these status responses. 1139 The state of a connection is only changed by successful commands 1140 which are documented as changing state. A rejected command (BAD 1141 response) never changes the state of the connection or of the 1142 selected mailbox. A failed command (NO response) generally does not 1143 change the state of the connection or of the selected mailbox; the 1144 exception being the SELECT and EXAMINE commands. 1146 6.1. Client Commands - Any State 1148 The following commands are valid in any state: CAPABILITY, NOOP, and 1149 LOGOUT. 1151 6.1.1. CAPABILITY Command 1153 Arguments: none 1155 Responses: REQUIRED untagged response: CAPABILITY 1156 Result: OK - capability completed 1157 BAD - command unknown or arguments invalid 1159 The CAPABILITY command requests a listing of capabilities that the 1160 server supports. The server MUST send a single untagged CAPABILITY 1161 response with "IMAP4rev2" as one of the listed capabilities before 1162 the (tagged) OK response. 1164 A capability name which begins with "AUTH=" indicates that the server 1165 supports that particular authentication mechanism. All such names 1166 are, by definition, part of this specification. For example, the 1167 authorization capability for an experimental "blurdybloop" 1168 authenticator would be "AUTH=XBLURDYBLOOP" and not 1169 "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP". 1171 Other capability names refer to extensions, revisions, or amendments 1172 to this specification. See the documentation of the CAPABILITY 1173 response for additional information. No capabilities, beyond the 1174 base IMAP4rev2 set defined in this specification, are enabled without 1175 explicit client action to invoke the capability. 1177 Client and server implementations MUST implement the STARTTLS, 1178 LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) capabilities. 1179 See the Security Considerations section for important information. 1181 See the section entitled "Client Commands - Experimental/Expansion" 1182 for information about the form of site or implementation-specific 1183 capabilities. 1185 Example: C: abcd CAPABILITY 1186 S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI 1187 LOGINDISABLED 1188 S: abcd OK CAPABILITY completed 1189 C: efgh STARTTLS 1190 S: efgh OK STARTLS completed 1191 1192 C: ijkl CAPABILITY 1193 S: * CAPABILITY IMAP4rev2 AUTH=GSSAPI AUTH=PLAIN 1194 S: ijkl OK CAPABILITY completed 1196 6.1.2. NOOP Command 1198 Arguments: none 1200 Responses: no specific responses for this command (but see below) 1202 Result: OK - noop completed 1203 BAD - command unknown or arguments invalid 1205 The NOOP command always succeeds. It does nothing. 1207 Since any command can return a status update as untagged data, the 1208 NOOP command can be used as a periodic poll for new messages or 1209 message status updates during a period of inactivity (the IDLE 1210 command Section 6.3.13 should be used instead of NOOP if real-time 1211 updates to mailbox state are desirable). The NOOP command can also 1212 be used to reset any inactivity autologout timer on the server. 1214 Example: C: a002 NOOP 1215 S: a002 OK NOOP completed 1216 . . . 1217 C: a047 NOOP 1218 S: * 22 EXPUNGE 1219 S: * 23 EXISTS 1220 S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted)) 1221 S: a047 OK NOOP completed 1223 6.1.3. LOGOUT Command 1225 Arguments: none 1227 Responses: REQUIRED untagged response: BYE 1229 Result: OK - logout completed 1230 BAD - command unknown or arguments invalid 1232 The LOGOUT command informs the server that the client is done with 1233 the connection. The server MUST send a BYE untagged response before 1234 the (tagged) OK response, and then close the network connection. 1236 Example: C: A023 LOGOUT 1237 S: * BYE IMAP4rev2 Server logging out 1238 S: A023 OK LOGOUT completed 1239 (Server and client then close the connection) 1241 6.2. Client Commands - Not Authenticated State 1243 In the not authenticated state, the AUTHENTICATE or LOGIN command 1244 establishes authentication and enters the authenticated state. The 1245 AUTHENTICATE command provides a general mechanism for a variety of 1246 authentication techniques, privacy protection, and integrity 1247 checking; whereas the LOGIN command uses a traditional user name and 1248 plaintext password pair and has no means of establishing privacy 1249 protection or integrity checking. 1251 The STARTTLS command is an alternate form of establishing session 1252 privacy protection and integrity checking, but does not by itself 1253 establish authentication or enter the authenticated state. 1255 Server implementations MAY allow access to certain mailboxes without 1256 establishing authentication. This can be done by means of the 1257 ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older 1258 convention is a LOGIN command using the userid "anonymous"; in this 1259 case, a password is required although the server may choose to accept 1260 any password. The restrictions placed on anonymous users are 1261 implementation-dependent. 1263 Once authenticated (including as anonymous), it is not possible to 1264 re-enter not authenticated state. 1266 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1267 the following commands are valid in the not authenticated state: 1268 STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations 1269 section for important information about these commands. 1271 6.2.1. STARTTLS Command 1273 Arguments: none 1275 Responses: no specific response for this command 1277 Result: OK - starttls completed, begin TLS negotiation 1278 BAD - command unknown or arguments invalid 1280 A [TLS] negotiation begins immediately after the CRLF at the end of 1281 the tagged OK response from the server. Once a client issues a 1282 STARTTLS command, it MUST NOT issue further commands until a server 1283 response is seen and the [TLS] negotiation is complete. 1285 The server remains in the non-authenticated state, even if client 1286 credentials are supplied during the [TLS] negotiation. This does not 1287 preclude an authentication mechanism such as EXTERNAL (defined in 1288 [SASL]) from using client identity determined by the [TLS] 1289 negotiation. 1291 Once [TLS] has been started, the client MUST discard cached 1292 information about server capabilities and SHOULD re-issue the 1293 CAPABILITY command. This is necessary to protect against man-in- 1294 the-middle attacks which alter the capabilities list prior to 1295 STARTTLS. The server MAY advertise different capabilities, and in 1296 particular SHOULD NOT advertise the STARTTLS capability, after a 1297 successful STARTTLS command. 1299 Example: C: a001 CAPABILITY 1300 S: * CAPABILITY IMAP4rev2 STARTTLS LOGINDISABLED 1301 S: a001 OK CAPABILITY completed 1302 C: a002 STARTTLS 1303 S: a002 OK Begin TLS negotiation now 1304 1305 C: a003 CAPABILITY 1306 S: * CAPABILITY IMAP4rev2 AUTH=PLAIN 1307 S: a003 OK CAPABILITY completed 1308 C: a004 LOGIN joe password 1309 S: a004 OK LOGIN completed 1311 6.2.2. AUTHENTICATE Command 1313 Arguments: SASL authentication mechanism name 1314 OPTIONAL initial response 1316 Responses: continuation data can be requested 1318 Result: OK - authenticate completed, now in authenticated state 1319 NO - authenticate failure: unsupported authentication 1320 mechanism, credentials rejected 1321 BAD - command unknown or arguments invalid, 1322 authentication exchange cancelled 1324 The AUTHENTICATE command indicates a [SASL] authentication mechanism 1325 to the server. If the server supports the requested authentication 1326 mechanism, it performs an authentication protocol exchange to 1327 authenticate and identify the client. It MAY also negotiate an 1328 OPTIONAL security layer for subsequent protocol interactions. If the 1329 requested authentication mechanism is not supported, the server 1330 SHOULD reject the AUTHENTICATE command by sending a tagged NO 1331 response. 1333 The AUTHENTICATE command supports the optional "initial response" 1334 feature defined in Section 5.1 of [SASL]. The client doesn't need to 1335 use it. If a SASL mechanism supports "initial response", but it is 1336 not specified by the client, the server handles this as specified in 1337 Section 3 of [SASL]. 1339 The service name specified by this protocol's profile of [SASL] is 1340 "imap". 1342 The authentication protocol exchange consists of a series of server 1343 challenges and client responses that are specific to the 1344 authentication mechanism. A server challenge consists of a command 1345 continuation request response with the "+" token followed by a BASE64 1346 encoded (see Section 4 of [RFC4648]) string. The client response 1347 consists of a single line consisting of a BASE64 encoded string. If 1348 the client wishes to cancel an authentication exchange, it issues a 1349 line consisting of a single "*". If the server receives such a 1350 response, or if it receives an invalid BASE64 string (e.g. 1351 characters outside the BASE64 alphabet, or non-terminal "="), it MUST 1352 reject the AUTHENTICATE command by sending a tagged BAD response. 1354 As with any other client response, this initial response MUST be 1355 encoded as BASE64. It also MUST be transmitted outside of a quoted 1356 string or literal. To send a zero-length initial response, the 1357 client MUST send a single pad character ("="). This indicates that 1358 the response is present, but is a zero-length string. 1360 When decoding the BASE64 data in the initial response, decoding 1361 errors MUST be treated as in any normal SASL client response, i.e. 1362 with a tagged BAD response. In particular, the server should check 1363 for any characters not explicitly allowed by the BASE64 alphabet, as 1364 well as any sequence of BASE64 characters that contains the pad 1365 character ('=') anywhere other than the end of the string (e.g., 1366 "=AAA" and "AAA=BBB" are not allowed). 1368 If the client uses an initial response with a SASL mechanism that 1369 does not support an initial response, the server MUST reject the 1370 command with a tagged BAD response. 1372 If a security layer is negotiated through the [SASL] authentication 1373 exchange, it takes effect immediately following the CRLF that 1374 concludes the authentication exchange for the client, and the CRLF of 1375 the tagged OK response for the server. 1377 While client and server implementations MUST implement the 1378 AUTHENTICATE command itself, it is not required to implement any 1379 authentication mechanisms other than the PLAIN mechanism described in 1380 [PLAIN]. Also, an authentication mechanism is not required to 1381 support any security layers. 1383 Note: a server implementation MUST implement a configuration in 1384 which it does NOT permit any plaintext password mechanisms, unless 1385 either the STARTTLS command has been negotiated or some other 1386 mechanism that protects the session from password snooping has 1387 been provided. Server sites SHOULD NOT use any configuration 1388 which permits a plaintext password mechanism without such a 1389 protection mechanism against password snooping. Client and server 1390 implementations SHOULD implement additional [SASL] mechanisms that 1391 do not use plaintext passwords, such the GSSAPI mechanism 1392 described in [SASL] and/or the SCRAM-SHA-256/SCRAM-SHA-256-PLUS 1393 [SCRAM-SHA-256] mechanisms. 1395 Servers and clients can support multiple authentication mechanisms. 1396 The server SHOULD list its supported authentication mechanisms in the 1397 response to the CAPABILITY command so that the client knows which 1398 authentication mechanisms to use. 1400 A server MAY include a CAPABILITY response code in the tagged OK 1401 response of a successful AUTHENTICATE command in order to send 1402 capabilities automatically. It is unnecessary for a client to send a 1403 separate CAPABILITY command if it recognizes these automatic 1404 capabilities. This should only be done if a security layer was not 1405 negotiated by the AUTHENTICATE command, because the tagged OK 1406 response as part of an AUTHENTICATE command is not protected by 1407 encryption/integrity checking. [SASL] requires the client to re- 1408 issue a CAPABILITY command in this case. The server MAY advertise 1409 different capabilities after a successful AUTHENTICATE command. 1411 If an AUTHENTICATE command fails with a NO response, the client MAY 1412 try another authentication mechanism by issuing another AUTHENTICATE 1413 command. It MAY also attempt to authenticate by using the LOGIN 1414 command (see Section 6.2.3 for more detail). In other words, the 1415 client MAY request authentication types in decreasing order of 1416 preference, with the LOGIN command as a last resort. 1418 The authorization identity passed from the client to the server 1419 during the authentication exchange is interpreted by the server as 1420 the user name whose privileges the client is requesting. 1422 Example: S: * OK IMAP4rev2 Server 1423 C: A001 AUTHENTICATE GSSAPI 1424 S: + 1425 C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw 1426 MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0 1427 b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW 1428 Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA 1429 cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX 1430 AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y 1431 C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb 1432 I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi 1433 vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL 1434 pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n 1435 FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE 1436 NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx 1437 O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB 1438 vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg== 1439 S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC 1440 AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0 1441 uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg== 1442 C: 1443 S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe 1444 ceP2CWY0SR0fAQAgAAQEBAQ= 1445 C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP 1446 wkhbfa2QteAQAgAG1yYwE= 1447 S: A001 OK GSSAPI authentication successful 1449 Note: The line breaks within server challenges and client responses 1450 are for editorial clarity and are not in real authenticators. 1452 6.2.3. LOGIN Command 1454 Arguments: user name 1455 password 1457 Responses: no specific responses for this command 1459 Result: OK - login completed, now in authenticated state 1460 NO - login failure: user name or password rejected 1461 BAD - command unknown or arguments invalid 1463 The LOGIN command identifies the client to the server and carries the 1464 plaintext password authenticating this user. 1466 A server MAY include a CAPABILITY response code in the tagged OK 1467 response to a successful LOGIN command in order to send capabilities 1468 automatically. It is unnecessary for a client to send a separate 1469 CAPABILITY command if it recognizes these automatic capabilities. 1471 Example: C: a001 LOGIN SMITH SESAME 1472 S: a001 OK LOGIN completed 1474 Note: Use of the LOGIN command over an insecure network (such as the 1475 Internet) is a security risk, because anyone monitoring network 1476 traffic can obtain plaintext passwords. The LOGIN command SHOULD NOT 1477 be used except as a last resort, and it is recommended that client 1478 implementations have a means to disable any automatic use of the 1479 LOGIN command. 1481 Unless either the client is accessing IMAP service on IMAPS port 1482 [RFC8314], the STARTTLS command has been negotiated or some other 1483 mechanism that protects the session from password snooping has been 1484 provided, a server implementation MUST implement a configuration in 1485 which it advertises the LOGINDISABLED capability and does NOT permit 1486 the LOGIN command. Server sites SHOULD NOT use any configuration 1487 which permits the LOGIN command without such a protection mechanism 1488 against password snooping. A client implementation MUST NOT send a 1489 LOGIN command if the LOGINDISABLED capability is advertised. 1491 6.3. Client Commands - Authenticated State 1493 In the authenticated state, commands that manipulate mailboxes as 1494 atomic entities are permitted. Of these commands, the SELECT and 1495 EXAMINE commands will select a mailbox for access and enter the 1496 selected state. 1498 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1499 the following commands are valid in the authenticated state: ENABLE, 1500 SELECT, EXAMINE, NAMESPACE, CREATE, DELETE, RENAME, SUBSCRIBE, 1501 UNSUBSCRIBE, LIST, STATUS, APPEND and IDLE. 1503 6.3.1. ENABLE Command 1505 Arguments: capability names 1507 Responses: no specific responses for this command 1509 Result: OK - Relevant capabilities enabled 1510 BAD - No arguments, or syntax error in an argument 1512 Several IMAP extensions allow the server to return unsolicited 1513 responses specific to these extensions in certain circumstances. 1514 However, servers cannot send those unsolicited responses (with the 1515 exception of response codes (see Section 7.1) included in tagged or 1516 untagged OK/NO/BAD responses, which can always be sent) until they 1517 know that the clients support such extensions and thus won't choke on 1518 the extension response data. 1520 The ENABLE command provides an explicit indication from the client 1521 that it supports particular extensions. It is designed such that the 1522 client can send a simple constant string with the extensions it 1523 supports, and the server will enable the shared subset that both 1524 support. 1526 The ENABLE command takes a list of capability names, and requests the 1527 server to enable the named extensions. Once enabled using ENABLE, 1528 each extension remains active until the IMAP connection is closed. 1529 For each argument, the server does the following: 1531 o If the argument is not an extension known to the server, the 1532 server MUST ignore the argument. 1534 o If the argument is an extension known to the server, and it is not 1535 specifically permitted to be enabled using ENABLE, the server MUST 1536 ignore the argument. (Note that knowing about an extension 1537 doesn't necessarily imply supporting that extension.) 1539 o If the argument is an extension that is supported by the server 1540 and that needs to be enabled, the server MUST enable the extension 1541 for the duration of the connection. Note that once an extension 1542 is enabled, there is no way to disable it. 1544 If the ENABLE command is successful, the server MUST send an untagged 1545 ENABLED response Section 7.2.1. 1547 Clients SHOULD only include extensions that need to be enabled by the 1548 server. For example, a client can enable IMAP4rev2 specific 1549 behaviour when both IMAP4rev1 and IMAP4rev2 are advertised in the 1550 CAPABILITY response. Future RFCs may add to this list. 1552 The ENABLE command is only valid in the authenticated state, before 1553 any mailbox is selected. Clients MUST NOT issue ENABLE once they 1554 SELECT/EXAMINE a mailbox; however, server implementations don't have 1555 to check that no mailbox is selected or was previously selected 1556 during the duration of a connection. 1558 The ENABLE command can be issued multiple times in a session. It is 1559 additive; i.e., "ENABLE a b", followed by "ENABLE c" is the same as a 1560 single command "ENABLE a b c". When multiple ENABLE commands are 1561 issued, each corresponding ENABLED response SHOULD only contain 1562 extensions enabled by the corresponding ENABLE command, i.e. for the 1563 above example, the ENABLED response to "ENABLE c" should not contain 1564 "a" or "b". 1566 There are no limitations on pipelining ENABLE. For example, it is 1567 possible to send ENABLE and then immediately SELECT, or a LOGIN 1568 immediately followed by ENABLE. 1570 The server MUST NOT change the CAPABILITY list as a result of 1571 executing ENABLE; i.e., a CAPABILITY command issued right after an 1572 ENABLE command MUST list the same capabilities as a CAPABILITY 1573 command issued before the ENABLE command. This is demonstrated in 1574 the following example: 1576 C: t1 CAPABILITY 1577 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1578 S: t1 OK foo 1579 C: t2 ENABLE CONDSTORE X-GOOD-IDEA 1580 S: * ENABLED X-GOOD-IDEA 1581 S: t2 OK foo 1582 C: t3 CAPABILITY 1583 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1584 S: t3 OK foo again 1586 In the following example, the client enables CONDSTORE: 1588 C: a1 ENABLE CONDSTORE 1589 S: * ENABLED CONDSTORE 1590 S: a1 OK Conditional Store enabled 1592 6.3.1.1. Note to Designers of Extensions That May Use the ENABLE 1593 Command 1595 Designers of IMAP extensions are discouraged from creating extensions 1596 that require ENABLE unless there is no good alternative design. 1597 Specifically, extensions that cause potentially incompatible behavior 1598 changes to deployed server responses (and thus benefit from ENABLE) 1599 have a higher complexity cost than extensions that do not. 1601 6.3.2. SELECT Command 1603 Arguments: mailbox name 1605 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1606 REQUIRED OK untagged responses: PERMANENTFLAGS, 1607 UIDNEXT, UIDVALIDITY 1608 OPTIONAL untagged response: LIST 1610 Result: OK - select completed, now in selected state 1611 NO - select failure, now in authenticated state: no 1612 such mailbox, can't access mailbox 1613 BAD - command unknown or arguments invalid 1615 The SELECT command selects a mailbox so that messages in the mailbox 1616 can be accessed. Before returning an OK to the client, the server 1617 MUST send the following untagged data to the client. (The order of 1618 individual responses is not important.) Note that earlier versions 1619 of this protocol only required the FLAGS and EXISTS untagged data; 1620 consequently, client implementations SHOULD implement default 1621 behavior for missing data as discussed with the individual item. 1623 FLAGS Defined flags in the mailbox. See the description of the 1624 FLAGS response for more detail. 1626 EXISTS The number of messages in the mailbox. See the 1627 description of the EXISTS response for more detail. 1629 LIST If the server allows de-normalized UTF-8 mailbox names (see 1630 Section 5.1) and the supplied mailbox name differs from the 1631 normalized version, the server SHOULD return LIST with OLDNAME 1632 extended data item. See Section 6.3.9.7 for more details. 1634 OK [PERMANENTFLAGS ()] A list of message flags that 1635 the client can change permanently. If this is missing, the client 1636 should assume that all flags can be changed permanently. 1638 OK [UIDNEXT ] The next unique identifier value. Refer to 1639 Section 2.3.1.1 for more information. If this is missing, the 1640 client can not make any assumptions about the next unique 1641 identifier value. 1643 OK [UIDVALIDITY ] The unique identifier validity value. Refer to 1644 Section 2.3.1.1 for more information. If this is missing, the 1645 server does not support unique identifiers. 1647 Only one mailbox can be selected at a time in a connection; 1648 simultaneous access to multiple mailboxes requires multiple 1649 connections. The SELECT command automatically deselects any 1650 currently selected mailbox before attempting the new selection. 1651 Consequently, if a mailbox is selected and a SELECT command that 1652 fails is attempted, no mailbox is selected. When deselecting a 1653 selected mailbox, the server MUST return an untagged OK response with 1654 the "[CLOSED]" response code when the currently selected mailbox is 1655 closed (see Paragraph 10). 1657 If the client is permitted to modify the mailbox, the server SHOULD 1658 prefix the text of the tagged OK response with the "[READ-WRITE]" 1659 response code. 1661 If the client is not permitted to modify the mailbox but is permitted 1662 read access, the mailbox is selected as read-only, and the server 1663 MUST prefix the text of the tagged OK response to SELECT with the 1664 "[READ-ONLY]" response code. Read-only access through SELECT differs 1665 from the EXAMINE command in that certain read-only mailboxes MAY 1666 permit the change of permanent state on a per-user (as opposed to 1667 global) basis. Netnews messages marked in a server-based .newsrc 1668 file are an example of such per-user permanent state that can be 1669 modified with read-only mailboxes. 1671 Example: C: A142 SELECT INBOX 1672 S: * 172 EXISTS 1673 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1674 S: * OK [UIDNEXT 4392] Predicted next UID 1675 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1676 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1677 S: A142 OK [READ-WRITE] SELECT completed 1679 Example: C: A142 SELECT INBOX 1680 S: * 172 EXISTS 1681 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1682 S: * OK [UIDNEXT 4392] Predicted next UID 1683 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1684 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1685 S: A142 OK [READ-WRITE] SELECT completed 1686 [...some time later...] 1687 C: A143 SELECT Drafts 1688 S: * OK [CLOSED] Previous mailbox is now closed 1689 S: * 5 EXISTS 1690 S: * OK [UIDVALIDITY 9877410381] UIDs valid 1691 S: * OK [UIDNEXT 102] Predicted next UID 1692 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1693 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Answered 1694 \Flagged \Draft \*)] System flags and keywords allowed 1695 S: A143 OK [READ-WRITE] SELECT completed 1697 Note that IMAP4rev1 compliant servers can also send the untagged 1698 RECENT response which was deprecated in IMAP4rev2. E.g. "* 0 1699 RECENT". Pure IMAP4rev2 clients are advised to ignore the untagged 1700 RECENT response. 1702 6.3.3. EXAMINE Command 1704 Arguments: mailbox name 1706 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1707 REQUIRED OK untagged responses: PERMANENTFLAGS, 1708 UIDNEXT, UIDVALIDITY 1709 OPTIONAL untagged response: LIST 1711 Result: OK - examine completed, now in selected state 1712 NO - examine failure, now in authenticated state: no 1713 such mailbox, can't access mailbox BAD - command unknown 1714 or arguments invalid 1716 The EXAMINE command is identical to SELECT and returns the same 1717 output; however, the selected mailbox is identified as read-only. No 1718 changes to the permanent state of the mailbox, including per-user 1719 state, are permitted. 1721 The text of the tagged OK response to the EXAMINE command MUST begin 1722 with the "[READ-ONLY]" response code. 1724 Example: C: A932 EXAMINE blurdybloop 1725 S: * 17 EXISTS 1726 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1727 S: * OK [UIDNEXT 4392] Predicted next UID 1728 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1729 S: * OK [PERMANENTFLAGS ()] No permanent flags permitted 1730 S: A932 OK [READ-ONLY] EXAMINE completed 1732 6.3.4. CREATE Command 1734 Arguments: mailbox name 1736 Responses: OPTIONAL untagged response: LIST 1738 Result: OK - create completed 1739 NO - create failure: can't create mailbox with that name 1740 BAD - command unknown or arguments invalid 1742 The CREATE command creates a mailbox with the given name. An OK 1743 response is returned only if a new mailbox with that name has been 1744 created. It is an error to attempt to create INBOX or a mailbox with 1745 a name that refers to an extant mailbox. Any error in creation will 1746 return a tagged NO response. If a client attempts to create a UTF-8 1747 mailbox name that is not a valid Net-Unicode name, the server MUST 1748 reject the creation or convert the name to Net-Unicode prior to 1749 creating the mailbox. If the server decides to convert (normalize) 1750 the name, it SHOULD return an untagged LIST with OLDNAME extended 1751 data item, with the OLDNAME value being the supplied mailbox name and 1752 the name parameter being the normalized mailbox name. (See 1753 Section 6.3.9.7 for more details.) 1755 Mailboxes created in one IMAP session MAY be announced to other IMAP 1756 sessions using unsolicited LIST response. If the server 1757 automatically subscribes a mailbox when it is created, then the 1758 unsolicited LIST response for each affected subscribed mailbox name 1759 MUST include the \Subscribed attribute. 1761 If the mailbox name is suffixed with the server's hierarchy separator 1762 character (as returned from the server by a LIST command), this is a 1763 declaration that the client intends to create mailbox names under 1764 this name in the hierarchy. Server implementations that do not 1765 require this declaration MUST ignore the declaration. In any case, 1766 the name created is without the trailing hierarchy delimiter. 1768 If the server's hierarchy separator character appears elsewhere in 1769 the name, the server SHOULD create any superior hierarchical names 1770 that are needed for the CREATE command to be successfully completed. 1771 In other words, an attempt to create "foo/bar/zap" on a server in 1772 which "/" is the hierarchy separator character SHOULD create foo/ and 1773 foo/bar/ if they do not already exist. 1775 If a new mailbox is created with the same name as a mailbox which was 1776 deleted, its unique identifiers MUST be greater than any unique 1777 identifiers used in the previous incarnation of the mailbox UNLESS 1778 the new incarnation has a different unique identifier validity value. 1779 See the description of the UID command for more detail. 1781 Example: C: A003 CREATE owatagusiam/ 1782 S: A003 OK CREATE completed 1783 C: A004 CREATE owatagusiam/blurdybloop 1784 S: A004 OK CREATE completed 1785 C: A005 CREATE NonNormalized 1786 S: * LIST () "/" "Normalized" ("OLDNAME" ("NonNormalized")) 1787 S: A005 OK CREATE completed 1789 (in the last example imagine that "NonNormalized" is 1790 a non NFC normalized Unicode mailbox name and that 1791 "Normalized" is its NFC normalized version.) 1793 Note: The interpretation of this example depends on whether "/" 1794 was returned as the hierarchy separator from LIST. If "/" is the 1795 hierarchy separator, a new level of hierarchy named "owatagusiam" 1796 with a member called "blurdybloop" is created. Otherwise, two 1797 mailboxes at the same hierarchy level are created. 1799 6.3.5. DELETE Command 1801 Arguments: mailbox name 1803 Responses: OPTIONAL untagged response: LIST 1805 Result: OK - delete completed 1806 NO - delete failure: can't delete mailbox with that name 1807 BAD - command unknown or arguments invalid 1809 The DELETE command permanently removes the mailbox with the given 1810 name. A tagged OK response is returned only if the mailbox has been 1811 deleted. It is an error to attempt to delete INBOX or a mailbox name 1812 that does not exist. 1814 The DELETE command MUST NOT remove inferior hierarchical names. For 1815 example, if a mailbox "foo" has an inferior "foo.bar" (assuming "." 1816 is the hierarchy delimiter character), removing "foo" MUST NOT remove 1817 "foo.bar". It is an error to attempt to delete a name that has 1818 inferior hierarchical names and also has the \Noselect mailbox name 1819 attribute (see the description of the LIST response for more 1820 details). 1822 It is permitted to delete a name that has inferior hierarchical names 1823 and does not have the \Noselect mailbox name attribute. If the 1824 server implementation does not permit deleting the name while 1825 inferior hierarchical names exists then it SHOULD disallow the DELETE 1826 command by returning a tagged NO response. The NO response SHOULD 1827 include the HASCHILDREN response code. Alternatively the server MAY 1828 allow the DELETE command, but sets the \Noselect mailbox name 1829 attribute for that name. 1831 If the server returns OK response, all messages in that mailbox are 1832 removed by the DELETE command. 1834 The value of the highest-used unique identifier of the deleted 1835 mailbox MUST be preserved so that a new mailbox created with the same 1836 name will not reuse the identifiers of the former incarnation, UNLESS 1837 the new incarnation has a different unique identifier validity value. 1838 See the description of the UID command for more detail. 1840 Mailboxes deleted in one IMAP session MAY be announced to other IMAP 1841 sessions using unsolicited LIST response, containing the 1842 "\NonExistent" attribute. 1844 Examples: C: A682 LIST "" * 1845 S: * LIST () "/" blurdybloop 1846 S: * LIST (\Noselect) "/" foo 1847 S: * LIST () "/" foo/bar 1848 S: A682 OK LIST completed 1849 C: A683 DELETE blurdybloop 1850 S: A683 OK DELETE completed 1851 C: A684 DELETE foo 1852 S: A684 NO Name "foo" has inferior hierarchical names 1853 C: A685 DELETE foo/bar 1854 S: A685 OK DELETE Completed 1855 C: A686 LIST "" * 1856 S: * LIST (\Noselect) "/" foo 1857 S: A686 OK LIST completed 1858 C: A687 DELETE foo 1859 S: A687 OK DELETE Completed 1860 C: A82 LIST "" * 1861 S: * LIST () "." blurdybloop 1862 S: * LIST () "." foo 1863 S: * LIST () "." foo.bar 1864 S: A82 OK LIST completed 1865 C: A83 DELETE blurdybloop 1866 S: A83 OK DELETE completed 1867 C: A84 DELETE foo 1868 S: A84 OK DELETE Completed 1869 C: A85 LIST "" * 1870 S: * LIST () "." foo.bar 1871 S: A85 OK LIST completed 1872 C: A86 LIST "" % 1873 S: * LIST (\Noselect) "." foo 1874 S: A86 OK LIST completed 1876 6.3.6. RENAME Command 1878 Arguments: existing mailbox name 1879 new mailbox name 1881 Responses: OPTIONAL untagged response: LIST 1883 Result: OK - rename completed 1884 NO - rename failure: can't rename mailbox with that name, 1885 can't rename to mailbox with that name 1886 BAD - command unknown or arguments invalid 1888 The RENAME command changes the name of a mailbox. A tagged OK 1889 response is returned only if the mailbox has been renamed. It is an 1890 error to attempt to rename from a mailbox name that does not exist or 1891 to a mailbox name that already exists. Any error in renaming will 1892 return a tagged NO response. 1894 If the name has inferior hierarchical names, then the inferior 1895 hierarchical names MUST also be renamed. For example, a rename of 1896 "foo" to "zap" will rename "foo/bar" (assuming "/" is the hierarchy 1897 delimiter character) to "zap/bar". 1899 If the server's hierarchy separator character appears in the name, 1900 the server SHOULD create any superior hierarchical names that are 1901 needed for the RENAME command to complete successfully. In other 1902 words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a 1903 server in which "/" is the hierarchy separator character in the 1904 corresponding namespace SHOULD create baz/ and baz/rag/ if they do 1905 not already exist. 1907 The value of the highest-used unique identifier of the old mailbox 1908 name MUST be preserved so that a new mailbox created with the same 1909 name will not reuse the identifiers of the former incarnation, UNLESS 1910 the new incarnation has a different unique identifier validity value. 1911 See the description of the UID command for more detail. 1913 Renaming INBOX is permitted, and has special behavior. (Note that 1914 some servers disallow renaming INBOX, so clients need to be able to 1915 handle such RENAME failing). It moves all messages in INBOX to a new 1916 mailbox with the given name, leaving INBOX empty. If the server 1917 implementation supports inferior hierarchical names of INBOX, these 1918 are unaffected by a rename of INBOX. 1920 If the server allows creation of mailboxes with names that are not 1921 valid Net-Unicode names, the server normalizes both the existing 1922 mailbox name parameter and the new mailbox name parameter. If the 1923 normalized version of any of these 2 parameters differs from the 1924 corresponding supplied version, the server SHOULD return an untagged 1925 LIST response with OLDNAME extended data item, with the OLDNAME value 1926 being the supplied existing mailbox name and the name parameter being 1927 the normalized new mailbox name (see Section 6.3.9.7). This would 1928 allow the client to correlate supplied name with the normalized name. 1930 Mailboxes renamed in one IMAP session MAY be announced to other IMAP 1931 sessions using unsolicited LIST response with OLDNAME extended data 1932 item. 1934 In both of the above cases: if the server automatically subscribes a 1935 mailbox when it is renamed, then the unsolicited LIST response for 1936 each affected subscribed mailbox name MUST include the \Subscribed 1937 attribute. No unsolicited LIST responses need to be sent for 1938 children mailboxes, if any. When INBOX is successfully renamed, a 1939 new INBOX is assumed to be created. No unsolicited LIST responses 1940 need to be sent for INBOX in this case. 1942 Examples: C: A682 LIST "" * 1943 S: * LIST () "/" blurdybloop 1944 S: * LIST (\Noselect) "/" foo 1945 S: * LIST () "/" foo/bar 1946 S: A682 OK LIST completed 1947 C: A683 RENAME blurdybloop sarasoop 1948 S: A683 OK RENAME completed 1949 C: A684 RENAME foo zowie 1950 S: A684 OK RENAME Completed 1951 C: A685 LIST "" * 1952 S: * LIST () "/" sarasoop 1953 S: * LIST (\Noselect) "/" zowie 1954 S: * LIST () "/" zowie/bar 1955 S: A685 OK LIST completed 1957 C: Z432 LIST "" * 1958 S: * LIST () "." INBOX 1959 S: * LIST () "." INBOX.bar 1960 S: Z432 OK LIST completed 1961 C: Z433 RENAME INBOX old-mail 1962 S: Z433 OK RENAME completed 1963 C: Z434 LIST "" * 1964 S: * LIST () "." INBOX 1965 S: * LIST () "." INBOX.bar 1966 S: * LIST () "." old-mail 1967 S: Z434 OK LIST completed 1969 Note that renaming a mailbox doesn't update subscription information 1970 on the original name. To keep subscription information in sync, the 1971 following sequence of commands can be used: 1973 C: 1001 RENAME X Y 1974 C: 1002 SUBSCRIBE Y 1975 C: 1003 UNSUBSCRIBE X 1977 Note that the above sequence of commands doesn't account for updating 1978 subscription for any children mailboxes of mailbox X. 1980 6.3.7. SUBSCRIBE Command 1982 Arguments: mailbox 1984 Responses: no specific responses for this command 1986 Result: OK - subscribe completed 1987 NO - subscribe failure: can't subscribe to that name 1988 BAD - command unknown or arguments invalid 1990 The SUBSCRIBE command adds the specified mailbox name to the server's 1991 set of "active" or "subscribed" mailboxes as returned by the LIST 1992 (SUBSCRIBED) command. This command returns a tagged OK response if 1993 the subscription is successful or if the mailbox is already 1994 subscribed. 1996 A server MAY validate the mailbox argument to SUBSCRIBE to verify 1997 that it exists. However, it SHOULD NOT unilaterally remove an 1998 existing mailbox name from the subscription list even if a mailbox by 1999 that name no longer exists. 2001 Note: This requirement is because a server site can choose to 2002 routinely remove a mailbox with a well-known name (e.g., "system- 2003 alerts") after its contents expire, with the intention of 2004 recreating it when new contents are appropriate. 2006 Example: C: A002 SUBSCRIBE #news.comp.mail.mime 2007 S: A002 OK SUBSCRIBE completed 2009 6.3.8. UNSUBSCRIBE Command 2011 Arguments: mailbox name 2013 Responses: no specific responses for this command 2015 Result: OK - unsubscribe completed 2016 NO - unsubscribe failure: can't unsubscribe that name 2017 BAD - command unknown or arguments invalid 2019 The UNSUBSCRIBE command removes the specified mailbox name from the 2020 server's set of "active" or "subscribed" mailboxes as returned by the 2021 LIST (SUBSCRIBED) command. This command returns a tagged OK response 2022 if the unsubscription is successful or if the mailbox is not 2023 subscribed. 2025 Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime 2026 S: A002 OK UNSUBSCRIBE completed 2028 6.3.9. LIST Command 2030 Arguments (basic): reference name 2031 mailbox name with possible wildcards 2033 Arguments (extended): selection options (OPTIONAL) 2034 reference name 2035 mailbox patterns 2036 return options (OPTIONAL) 2038 Responses: untagged responses: LIST 2040 Result: OK - list completed 2041 NO - list failure: can't list that reference or name 2042 BAD - command unknown or arguments invalid 2044 The LIST command returns a subset of names from the complete set of 2045 all names available to the client. Zero or more untagged LIST 2046 replies are returned, containing the name attributes, hierarchy 2047 delimiter, name, and possible extension information; see the 2048 description of the LIST reply for more detail. 2050 The LIST command SHOULD return its data quickly, without undue delay. 2051 For example, it SHOULD NOT go to excess trouble to calculate the 2052 \Marked or \Unmarked status or perform other processing; if each name 2053 requires 1 second of processing, then a list of 1200 names would take 2054 20 minutes! 2056 The extended LIST command, originally introduced in [RFC5258], 2057 provides capabilities beyond that of the original IMAP LIST command. 2058 The extended syntax is being used if one or more of the following 2059 conditions is true: 2061 1. if the first word after the command name begins with a 2062 parenthesis ("LIST selection options"); 2064 2. if the second word after the command name begins with a 2065 parenthesis; 2067 3. if the LIST command has more than 2 parameters ("LIST return 2068 options") 2070 An empty ("" string) reference name argument indicates that the 2071 mailbox name is interpreted as by SELECT. The returned mailbox names 2072 MUST match the supplied mailbox name pattern(s). A non-empty 2073 reference name argument is the name of a mailbox or a level of 2074 mailbox hierarchy, and indicates the context in which the mailbox 2075 name is interpreted. Clients SHOULD use the empty reference 2076 argument. 2078 In the basic syntax only, an empty ("" string) mailbox name argument 2079 is a special request to return the hierarchy delimiter and the root 2080 name of the name given in the reference. The value returned as the 2081 root MAY be the empty string if the reference is non-rooted or is an 2082 empty string. In all cases, a hierarchy delimiter (or NIL if there 2083 is no hierarchy) is returned. This permits a client to get the 2084 hierarchy delimiter (or find out that the mailbox names are flat) 2085 even when no mailboxes by that name currently exist. 2087 In the extended syntax, any mailbox name arguments that are empty 2088 strings are ignored. There is no special meaning for empty mailbox 2089 names when the extended syntax is used. 2091 The reference and mailbox name arguments are interpreted into a 2092 canonical form that represents an unambiguous left-to-right 2093 hierarchy. The returned mailbox names will be in the interpreted 2094 form, that we call "canonical LIST pattern" later in this document. 2095 To define the term "canonical LIST pattern" formally: it refers to 2096 the canonical pattern constructed internally by the server from the 2097 reference and mailbox name arguments. 2099 Note: The interpretation of the reference argument is 2100 implementation-defined. It depends upon whether the server 2101 implementation has a concept of the "current working directory" 2102 and leading "break out characters", which override the current 2103 working directory. 2105 For example, on a server which exports a UNIX or NT filesystem, 2106 the reference argument contains the current working directory, and 2107 the mailbox name argument would contain the name as interpreted in 2108 the current working directory. 2110 If a server implementation has no concept of break out characters, 2111 the canonical form is normally the reference name appended with 2112 the mailbox name. Note that if the server implements the 2113 namespace convention (Section 5.1.2.1), "#" is a break out 2114 character and must be treated as such. 2116 If the reference argument is not a level of mailbox hierarchy 2117 (that is, it is a \NoInferiors name), and/or the reference 2118 argument does not end with the hierarchy delimiter, it is 2119 implementation-dependent how this is interpreted. For example, a 2120 reference of "foo/bar" and mailbox name of "rag/baz" could be 2121 interpreted as "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/ 2122 baz". A client SHOULD NOT use such a reference argument except at 2123 the explicit request of the user. A hierarchical browser MUST NOT 2124 make any assumptions about server interpretation of the reference 2125 unless the reference is a level of mailbox hierarchy AND ends with 2126 the hierarchy delimiter. 2128 Any part of the reference argument that is included in the 2129 interpreted form SHOULD prefix the interpreted form. It SHOULD also 2130 be in the same form as the reference name argument. This rule 2131 permits the client to determine if the returned mailbox name is in 2132 the context of the reference argument, or if something about the 2133 mailbox argument overrode the reference argument. Without this rule, 2134 the client would have to have knowledge of the server's naming 2135 semantics including what characters are "breakouts" that override a 2136 naming context. 2138 For example, here are some examples of how references 2139 and mailbox names might be interpreted on a UNIX-based 2140 server: 2142 Reference Mailbox Name Interpretation 2143 ------------ ------------ -------------- 2144 ~smith/Mail/ foo.* ~smith/Mail/foo.* 2145 archive/ % archive/% 2146 #news. comp.mail.* #news.comp.mail.* 2147 ~smith/Mail/ /usr/doc/foo /usr/doc/foo 2148 archive/ ~fred/Mail/* ~fred/Mail/* 2150 The first three examples demonstrate interpretations in 2151 the context of the reference argument. Note that 2152 "~smith/Mail" SHOULD NOT be transformed into something 2153 like "/u2/users/smith/Mail", or it would be impossible 2154 for the client to determine that the interpretation was 2155 in the context of the reference. 2157 The character "*" is a wildcard, and matches zero or more characters 2158 at this position. The character "%" is similar to "*", but it does 2159 not match a hierarchy delimiter. If the "%" wildcard is the last 2160 character of a mailbox name argument, matching levels of hierarchy 2161 are also returned. If these levels of hierarchy are not also 2162 selectable mailboxes, they are returned with the \Noselect mailbox 2163 name attribute (see the description of the LIST response for more 2164 details). 2166 Any syntactically valid pattern that is not accepted by a server for 2167 any reason MUST be silently ignored. I.e. it results in no LIST 2168 responses and the LIST command still returns tagged OK response. 2170 Selection options tell the server to limit the mailbox names that are 2171 selected by the LIST operation. If selection options are used, the 2172 mailboxes returned are those that match both the list of canonical 2173 LIST patterns and the selection options. Unless a particular 2174 selection option provides special rules, the selection options are 2175 cumulative: a mailbox that matches the mailbox patterns is selected 2176 only if it also matches all of the selection options. (An example of 2177 a selection option with special rules is the RECURSIVEMATCH option.) 2178 Return options control what information is returned for each matched 2179 mailbox. Return options MUST NOT cause the server to report 2180 information about additional mailbox names other than those that 2181 match the canonical LIST patterns and selection options. If no 2182 return options are specified, the client is only expecting 2183 information about mailbox attributes. The server MAY return other 2184 information about the matched mailboxes, and clients MUST be able to 2185 handle that situation. 2187 Initial selection options and return options are defined in the 2188 following subsections, and new ones will also be defined in 2189 extensions. Initial options defined in this document MUST be 2190 supported. Each non-initial option will be enabled by a capability 2191 string (one capability may enable multiple options), and a client 2192 MUST NOT send an option for which the server has not advertised 2193 support. A server MUST respond to options it does not recognize with 2194 a BAD response. The client SHOULD NOT specify any option more than 2195 once; however, if the client does this, the server MUST act as if it 2196 received the option only once. The order in which options are 2197 specified by the client is not significant. 2199 In general, each selection option except RECURSIVEMATCH will have a 2200 corresponding return option with the same name. The REMOTE selection 2201 option is an anomaly in this regard, and does not have a 2202 corresponding return option. That is because it expands, rather than 2203 restricts, the set of mailboxes that are returned. Future extensions 2204 to this specification should keep this parallelism in mind and define 2205 a pair of corresponding selection and return options. 2207 Server implementations are permitted to "hide" otherwise accessible 2208 mailboxes from the wildcard characters, by preventing certain 2209 characters or names from matching a wildcard in certain situations. 2210 For example, a UNIX-based server might restrict the interpretation of 2211 "*" so that an initial "/" character does not match. 2213 The special name INBOX is included in the output from LIST, if INBOX 2214 is supported by this server for this user and if the uppercase string 2215 "INBOX" matches the interpreted reference and mailbox name arguments 2216 with wildcards as described above. The criteria for omitting INBOX 2217 is whether SELECT INBOX will return failure; it is not relevant 2218 whether the user's real INBOX resides on this or some other server. 2220 6.3.9.1. LIST Selection Options 2222 The selection options defined in this specification are as follows: 2224 SUBSCRIBED - causes the LIST command to list subscribed names, 2225 rather than the existing mailboxes. This will often be a subset 2226 of the actual mailboxes. It's also possible for this list to 2227 contain the names of mailboxes that don't exist. In any case, the 2228 list MUST include exactly those mailbox names that match the 2229 canonical list pattern and are subscribed to. 2231 This option defines a mailbox attribute, "\Subscribed", that 2232 indicates that a mailbox name is subscribed to. The "\Subscribed" 2233 attribute MUST be supported and MUST be accurately computed when 2234 the SUBSCRIBED selection option is specified. 2236 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 2237 return option (see below). 2239 REMOTE - causes the LIST command to show remote mailboxes as well as 2240 local ones, as described in [RFC2193]. This option is intended to 2241 replace the RLIST command and, in conjunction with the SUBSCRIBED 2242 selection option, the RLSUB command. Servers that don't support 2243 remote mailboxes just ignore this option. 2245 This option defines a mailbox attribute, "\Remote", that indicates 2246 that a mailbox is a remote mailbox. The "\Remote" attribute MUST 2247 be accurately computed when the REMOTE option is specified. 2249 The REMOTE selection option has no interaction with other options. 2250 Its effect is to tell the server to apply the other options, if 2251 any, to remote mailboxes, in addition to local ones. In 2252 particular, it has no interaction with RECURSIVEMATCH (see below). 2253 A request for (REMOTE RECURSIVEMATCH) is invalid, because a 2254 request for (RECURSIVEMATCH) is also invalid. A request for 2255 (REMOTE RECURSIVEMATCH SUBSCRIBED) is asking for all subscribed 2256 mailboxes, both local and remote. 2258 RECURSIVEMATCH - this option forces the server to return information 2259 about parent mailboxes that don't match other selection options, 2260 but have some submailboxes that do. Information about children is 2261 returned in the CHILDINFO extended data item, as described in 2262 Section 6.3.9.6. 2264 Note 1: In order for a parent mailbox to be returned, it still has 2265 to match the canonical LIST pattern. 2267 Note 2: When returning the CHILDINFO extended data item, it 2268 doesn't matter whether or not the submailbox matches the canonical 2269 LIST pattern. See also example 9 in Section 6.3.9.8. 2271 The RECURSIVEMATCH option MUST NOT occur as the only selection 2272 option (or only with REMOTE), as it only makes sense when other 2273 selection options are also used. The server MUST return BAD 2274 tagged response in such case. 2276 Note that even if the RECURSIVEMATCH option is specified, the 2277 client MUST still be able to handle a case when a CHILDINFO 2278 extended data item is returned and there are no submailboxes that 2279 meet the selection criteria of the subsequent LIST command, as 2280 they can be deleted/renamed after the LIST response was sent, but 2281 before the client had a chance to access them. 2283 6.3.9.2. LIST Return Options 2285 The return options defined in this specification are as follows: 2287 SUBSCRIBED - causes the LIST command to return subscription state 2288 for all matching mailbox names. The "\Subscribed" attribute MUST 2289 be supported and MUST be accurately computed when the SUBSCRIBED 2290 return option is specified. Further, all mailbox flags MUST be 2291 accurately computed (this differs from the behavior of the 2292 obsolete LSUB command from IMAP4rev1). 2294 CHILDREN - requests mailbox child information as originally proposed 2295 in [RFC3348]. See Section 6.3.9.5, below, for details. This 2296 option MUST be supported by all servers. 2298 STATUS - requests STATUS response for each matching mailbox. 2300 This option takes STATUS data items as parameters. For each 2301 selectable mailbox matching the list pattern and selection 2302 options, the server MUST return an untagged LIST response 2303 followed by an untagged STATUS response containing the 2304 information requested in the STATUS return option, except for 2305 some cases described below. 2307 If an attempted STATUS for a listed mailbox fails because the 2308 mailbox can't be selected (e.g., if the "l" ACL right [RFC4314] 2309 is granted to the mailbox and the "r" right is not granted, or 2310 due to a race condition between LIST and STATUS changing the 2311 mailbox to \NoSelect), the STATUS response MUST NOT be returned 2312 and the LIST response MUST include the \NoSelect attribute. 2313 This means the server may have to buffer the LIST reply until 2314 it has successfully looked up the necessary STATUS information. 2316 If the server runs into unexpected problems while trying to 2317 look up the STATUS information, it MAY drop the corresponding 2318 STATUS reply. In such a situation, the LIST command would 2319 still return a tagged OK reply. 2321 6.3.9.3. General Principles for Returning LIST Responses 2323 This section outlines several principles that can be used by server 2324 implementations of this document to decide whether a LIST response 2325 should be returned, as well as how many responses and what kind of 2326 information they may contain. 2328 1. At most one LIST response should be returned for each mailbox 2329 name that matches the canonical LIST pattern. Server 2330 implementors must not assume that clients will be able to 2331 assemble mailbox attributes and other information returned in 2332 multiple LIST responses. 2334 2. There are only two reasons for including a matching mailbox name 2335 in the responses to the LIST command (note that the server is 2336 allowed to return unsolicited responses at any time, and such 2337 responses are not governed by this rule): 2339 A. The mailbox name also satisfies the selection criteria. 2341 B. The mailbox name doesn't satisfy the selection criteria, but 2342 it has at least one descendant mailbox name that satisfies 2343 the selection criteria and that doesn't match the canonical 2344 LIST pattern. 2346 For more information on this case, see the CHILDINFO extended 2347 data item described in Section 6.3.9.6. Note that the 2348 CHILDINFO extended data item can only be returned when the 2349 RECURSIVEMATCH selection option is specified. 2351 3. Attributes returned in the same LIST response must be treated 2352 additively. For example, the following response 2354 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2356 means that the "Fruit/Peach" mailbox doesn't exist, but it is 2357 subscribed. 2359 6.3.9.4. Additional LIST-related Requirements on Clients 2361 All clients MUST treat a LIST attribute with a stronger meaning as 2362 implying any attribute that can be inferred from it. (See 2363 Section 7.2.3 for the list of currently defined attributes). For 2364 example, the client must treat the presence of the \NoInferiors 2365 attribute as if the \HasNoChildren attribute was also sent by the 2366 server. 2368 The following table summarizes inference rules. 2370 +--------------------+-------------------+ 2371 | returned attribute | implied attribute | 2372 +--------------------+-------------------+ 2373 | \NoInferiors | \HasNoChildren | 2374 | \NonExistent | \NoSelect | 2375 +--------------------+-------------------+ 2377 6.3.9.5. The CHILDREN Return Option 2379 The CHILDREN return option is simply an indication that the client 2380 wants information about whether or not mailboxes contain children 2381 mailboxes; a server MAY provide it even if the option is not 2382 specified. 2384 Many IMAP4 clients present to the user a hierarchical view of the 2385 mailboxes that a user has access to. Rather than initially 2386 presenting to the user the entire mailbox hierarchy, it is often 2387 preferable to show to the user a collapsed outline list of the 2388 mailbox hierarchy (particularly if there is a large number of 2389 mailboxes). The user can then expand the collapsed outline hierarchy 2390 as needed. It is common to include within the collapsed hierarchy a 2391 visual clue (such as a ''+'') to indicate that there are child 2392 mailboxes under a particular mailbox. When the visual clue is 2393 clicked, the hierarchy list is expanded to show the child mailboxes. 2394 The CHILDREN return option provides a mechanism for a client to 2395 efficiently determine whether a particular mailbox has children, 2396 without issuing a LIST "" * or a LIST "" % for each mailbox name. 2397 The CHILDREN return option defines two new attributes that MUST be 2398 returned within a LIST response: \HasChildren and \HasNoChildren. 2399 Although these attributes MAY be returned in response to any LIST 2400 command, the CHILDREN return option is provided to indicate that the 2401 client particularly wants this information. If the CHILDREN return 2402 option is present, the server MUST return these attributes even if 2403 their computation is expensive. 2405 \HasChildren 2407 The presence of this attribute indicates that the mailbox has 2408 child mailboxes. A server SHOULD NOT set this attribute if 2409 there are child mailboxes and the user does not have permission 2410 to access any of them. In this case, \HasNoChildren SHOULD be 2411 used. In many cases, however, a server may not be able to 2412 efficiently compute whether a user has access to any child 2413 mailbox. Note that even though the \HasChildren attribute for a 2414 mailbox must be correct at the time of processing of the 2415 mailbox, a client must be prepared to deal with a situation when 2416 a mailbox is marked with the \HasChildren attribute, but no 2417 child mailbox appears in the response to the LIST command. This 2418 might happen, for example, due to children mailboxes being 2419 deleted or made inaccessible to the user (using access control) 2420 by another client before the server is able to list them. 2422 \HasNoChildren 2424 The presence of this attribute indicates that the mailbox has NO 2425 child mailboxes that are accessible to the currently 2426 authenticated user. 2428 It is an error for the server to return both a \HasChildren and a 2429 \HasNoChildren attribute in the same LIST response. 2431 Note: the \HasNoChildren attribute should not be confused with the 2432 the \NoInferiors attribute, which indicates that no child mailboxes 2433 exist now and none can be created in the future. 2435 6.3.9.6. CHILDINFO Extended Data Item 2437 The CHILDINFO extended data item MUST NOT be returned unless the 2438 client has specified the RECURSIVEMATCH selection option. 2440 The CHILDINFO extended data item in a LIST response describes the 2441 selection criteria that has caused it to be returned and indicates 2442 that the mailbox has at least one descendant mailbox that matches the 2443 selection criteria. 2445 Note: Some servers allow for mailboxes to exist without requiring 2446 their parent to exist. For example, a mailbox "Customers/ABC" can 2447 exist while the mailbox "Customers" does not. As CHILDINFO extended 2448 data item is not allowed if the RECURSIVEMATCH selection option is 2449 not specified, such servers SHOULD use the "\NonExistent 2450 \HasChildren" attribute pair to signal to the client that there is a 2451 descendant mailbox that matches the selection criteria. See example 2452 11 in Section 6.3.9.8. 2454 The returned selection criteria allow the client to distinguish a 2455 solicited response from an unsolicited one, as well as to distinguish 2456 among solicited responses caused by multiple pipelined LIST commands 2457 that specify different criteria. 2459 Servers SHOULD ONLY return a non-matching mailbox name along with 2460 CHILDINFO if at least one matching child is not also being returned. 2461 That is, servers SHOULD suppress redundant CHILDINFO responses. 2463 Examples 8 and 10 in Section 6.3.9.8 demonstrate the difference 2464 between present CHILDINFO extended data item and the "\HasChildren" 2465 attribute. 2467 The following table summarizes interaction between the "\NonExistent" 2468 attribute and CHILDINFO (the first column indicates whether the 2469 parent mailbox exists): 2471 +--------+-------------+------------------+-------------------------+ 2472 | exists | meets the | has a child that | returned | 2473 | | selection | meets the | IMAP4rev2/LIST-EXTENDED | 2474 | | criteria | selection | attributes and | 2475 | | | criteria | CHILDINFO | 2476 +--------+-------------+------------------+-------------------------+ 2477 | no | no | no | no LIST response | 2478 | | | | returned | 2479 | yes | no | no | no LIST response | 2480 | | | | returned | 2481 | no | yes | no | (\NonExistent ) | 2482 | yes | yes | no | () | 2483 | no | no | yes | (\NonExistent) + | 2484 | | | | CHILDINFO | 2485 | yes | no | yes | () + CHILDINFO | 2486 | no | yes | yes | (\NonExistent ) + | 2487 | | | | CHILDINFO | 2488 | yes | yes | yes | () + CHILDINFO | 2489 +--------+-------------+------------------+-------------------------+ 2491 where is one or more attributes that correspond to the 2492 selection criteria; for example, for the SUBSCRIBED option the 2493 is \Subscribed. 2495 6.3.9.7. OLDNAME Extended Data Item 2497 The OLDNAME extended data item is included when a mailbox name is 2498 created (with CREATE command), renamed (with RENAME command) or 2499 deleted (with DELETE command). (When a mailbox is deleted the 2500 "\NonExistent" attribute is also included.) IMAP extensions can 2501 specify other conditions when OLDNAME extended data item should be 2502 included. 2504 If the server allows de-normalized mailbox names (see Section 5.1) in 2505 SELECT/EXAMINE, CREATE, RENAME or DELETE, it SHOULD return an 2506 unsolicited LIST response that includes OLDNAME extended data item, 2507 whenever the supplied mailbox name differs from the resulting 2508 normalized mailbox name. From the client point of view this is 2509 indistinguishable from another user renaming of deleting the mailbox, 2510 as specified in the previous paragraph. 2512 A deleted mailbox can be announced like this: 2514 S: * LIST (\NonExistent) "." "INBOX.DeletedMailbox" 2516 Example of a renamed mailbox: 2518 S: * LIST () "/" "NewMailbox" ("OLDNAME" ("OldMailbox")) 2520 6.3.9.8. LIST Command Examples 2522 This example shows some uses of the basic LIST command: 2524 Example: C: A101 LIST "" "" 2525 S: * LIST (\Noselect) "/" "" 2526 S: A101 OK LIST Completed 2527 C: A102 LIST #news.comp.mail.misc "" 2528 S: * LIST (\Noselect) "." #news. 2529 S: A102 OK LIST Completed 2530 C: A103 LIST /usr/staff/jones "" 2531 S: * LIST (\Noselect) "/" / 2532 S: A103 OK LIST Completed 2533 C: A202 LIST ~/Mail/ % 2534 S: * LIST (\Noselect) "/" ~/Mail/foo 2535 S: * LIST () "/" ~/Mail/meetings 2536 S: A202 OK LIST completed 2538 Extended examples: 2540 1: The first example shows the complete local hierarchy that will 2541 be used for the other examples. 2543 C: A01 LIST "" "*" 2544 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2545 S: * LIST () "/" "Fruit" 2546 S: * LIST () "/" "Fruit/Apple" 2547 S: * LIST () "/" "Fruit/Banana" 2548 S: * LIST () "/" "Tofu" 2549 S: * LIST () "/" "Vegetable" 2550 S: * LIST () "/" "Vegetable/Broccoli" 2551 S: * LIST () "/" "Vegetable/Corn" 2552 S: A01 OK done 2554 2: In the next example, we will see the subscribed mailboxes. This 2555 is similar to, but not equivalent with now deprecated, (see [RFC3501] for more details on LSUB command). Note 2557 that the mailbox called "Fruit/Peach" is subscribed to, but does 2558 not actually exist (perhaps it was deleted while still 2559 subscribed). The "Fruit" mailbox is not subscribed to, but it 2560 has two subscribed children. The "Vegetable" mailbox is 2561 subscribed and has two children; one of them is subscribed as 2562 well. 2564 C: A02 LIST (SUBSCRIBED) "" "*" 2565 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2566 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2567 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2568 S: * LIST (\Subscribed) "/" "Vegetable" 2569 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2570 S: A02 OK done 2572 3: The next example shows the use of the CHILDREN option. The 2573 client, without having to list the second level of hierarchy, 2574 now knows which of the top-level mailboxes have submailboxes 2575 (children) and which do not. Note that it's not necessary for 2576 the server to return the \HasNoChildren attribute for the inbox, 2577 because the \NoInferiors attribute already implies that, and has 2578 a stronger meaning. 2580 C: A03 LIST () "" "%" RETURN (CHILDREN) 2581 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2582 S: * LIST (\HasChildren) "/" "Fruit" 2583 S: * LIST (\HasNoChildren) "/" "Tofu" 2584 S: * LIST (\HasChildren) "/" "Vegetable" 2585 S: A03 OK done 2587 4: In this example, we see more mailboxes that reside on another 2588 server. This is similar to the command . 2590 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 2591 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2592 S: * LIST (\HasChildren) "/" "Fruit" 2593 S: * LIST (\HasNoChildren) "/" "Tofu" 2594 S: * LIST (\HasChildren) "/" "Vegetable" 2595 S: * LIST (\Remote) "/" "Bread" 2596 S: * LIST (\HasChildren \Remote) "/" "Meat" 2597 S: A04 OK done 2599 5: The following example also requests the server to include 2600 mailboxes that reside on another server. The server returns 2601 information about all mailboxes that are subscribed. This is 2602 similar to the command (see [RFC2193] for more 2603 details on RLSUB). We also see the use of two selection 2604 options. 2606 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 2607 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2608 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2609 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2610 S: * LIST (\Subscribed) "/" "Vegetable" 2611 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2612 S: * LIST (\Remote \Subscribed) "/" "Bread" 2613 S: A05 OK done 2615 6: The following example requests the server to include mailboxes 2616 that reside on another server. The server is asked to return 2617 subscription information for all returned mailboxes. This is 2618 different from the example above. 2620 Note that the output of this command is not a superset of the 2621 output in the previous example, as it doesn't include LIST 2622 response for the non-existent "Fruit/Peach". 2624 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 2625 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2626 S: * LIST () "/" "Fruit" 2627 S: * LIST () "/" "Fruit/Apple" 2628 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2629 S: * LIST () "/" "Tofu" 2630 S: * LIST (\Subscribed) "/" "Vegetable" 2631 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2632 S: * LIST () "/" "Vegetable/Corn" 2633 S: * LIST (\Remote \Subscribed) "/" "Bread" 2634 S: * LIST (\Remote) "/" "Meat" 2635 S: A06 OK done 2637 7: The following example demonstrates the difference between the 2638 \HasChildren attribute and the CHILDINFO extended data item. 2640 Let's assume there is the following hierarchy: 2642 C: C01 LIST "" "*" 2643 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2644 S: * LIST () "/" "Foo" 2645 S: * LIST () "/" "Foo/Bar" 2646 S: * LIST () "/" "Foo/Baz" 2647 S: * LIST () "/" "Moo" 2648 S: C01 OK done 2650 If the client asks RETURN (CHILDREN), it will get this: 2652 C: CA3 LIST "" "%" RETURN (CHILDREN) 2653 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2654 S: * LIST (\HasChildren) "/" "Foo" 2655 S: * LIST (\HasNoChildren) "/" "Moo" 2656 S: CA3 OK done 2658 A) Let's also assume that the mailbox "Foo/Baz" is the only 2659 subscribed mailbox. Then we get this result: 2661 C: C02 LIST (SUBSCRIBED) "" "*" 2662 S: * LIST (\Subscribed) "/" "Foo/Baz" 2663 S: C02 OK done 2665 Now, if the client issues , the server 2666 will return no mailboxes (as the mailboxes "Moo", "Foo", and 2667 "Inbox" are NOT subscribed). However, if the client issues 2668 this: 2670 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2671 S: * LIST () "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2672 S: C04 OK done 2674 (i.e., the mailbox "Foo" is not subscribed, but it has a child 2675 that is.) 2677 A1) If the mailbox "Foo" had also been subscribed, the last 2678 command would return this: 2680 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2681 S: * LIST (\Subscribed) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2682 S: C04 OK done 2684 or even this: 2686 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2687 S: * LIST (\Subscribed \HasChildren) "/" "Foo" ("CHILDINFO" 2688 ("SUBSCRIBED")) 2689 S: C04 OK done 2691 A2) If we assume instead that the mailbox "Foo" is not part of 2692 the original hierarchy and is not subscribed, the last command 2693 will give this result: 2695 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2696 S: * LIST (\NonExistent) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2697 S: C04 OK done 2698 B) Now, let's assume that no mailbox is subscribed. In this 2699 case, the command will 2700 return no responses, as there are no subscribed children (even 2701 though "Foo" has children). 2703 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 2704 are subscribed. In that case, we see this result: 2706 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 2707 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 2708 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 2709 S: C04 OK done 2711 (which means that the mailbox "Foo" has children, but none of 2712 them is subscribed). 2714 8: The following example demonstrates that the CHILDINFO extended 2715 data item is returned whether or not children mailboxes match 2716 the canonical LIST pattern. 2718 Let's assume there is the following hierarchy: 2720 C: D01 LIST "" "*" 2721 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2722 S: * LIST () "/" "foo2" 2723 S: * LIST () "/" "foo2/bar1" 2724 S: * LIST () "/" "foo2/bar2" 2725 S: * LIST () "/" "baz2" 2726 S: * LIST () "/" "baz2/bar2" 2727 S: * LIST () "/" "baz2/bar22" 2728 S: * LIST () "/" "baz2/bar222" 2729 S: * LIST () "/" "eps2" 2730 S: * LIST () "/" "eps2/mamba" 2731 S: * LIST () "/" "qux2/bar2" 2732 S: D01 OK done 2734 And that the following mailboxes are subscribed: 2736 C: D02 LIST (SUBSCRIBED) "" "*" 2737 S: * LIST (\Subscribed) "/" "foo2/bar1" 2738 S: * LIST (\Subscribed) "/" "foo2/bar2" 2739 S: * LIST (\Subscribed) "/" "baz2/bar2" 2740 S: * LIST (\Subscribed) "/" "baz2/bar22" 2741 S: * LIST (\Subscribed) "/" "baz2/bar222" 2742 S: * LIST (\Subscribed) "/" "eps2" 2743 S: * LIST (\Subscribed) "/" "eps2/mamba" 2744 S: * LIST (\Subscribed) "/" "qux2/bar2" 2745 S: D02 OK done 2746 The client issues the following command first: 2748 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 2749 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2750 S: * LIST (\Subscribed) "/" "foo2/bar2" 2751 S: * LIST (\Subscribed) "/" "baz2/bar2" 2752 S: * LIST (\Subscribed) "/" "baz2/bar22" 2753 S: * LIST (\Subscribed) "/" "baz2/bar222" 2754 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2755 S: * LIST (\Subscribed) "/" "qux2/bar2" 2756 S: D03 OK done 2758 and the server may also include (but this would violate a SHOULD 2759 NOT in Section 3.5, because CHILDINFO is redundant) 2761 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2762 S: * LIST (\NonExistent) "/" "qux2" ("CHILDINFO" ("SUBSCRIBED")) 2764 The CHILDINFO extended data item is returned for mailboxes 2765 "foo2", "baz2", and "eps2", because all of them have subscribed 2766 children, even though for the mailbox "foo2" only one of the two 2767 subscribed children matches the pattern, for the mailbox "baz2" 2768 all the subscribed children match the pattern, and for the 2769 mailbox "eps2" none of the subscribed children matches the 2770 pattern. 2772 Note that if the client issues 2774 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 2775 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2776 S: * LIST (\Subscribed) "/" "foo2/bar1" 2777 S: * LIST (\Subscribed) "/" "foo2/bar2" 2778 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2779 S: * LIST (\Subscribed) "/" "baz2/bar2" 2780 S: * LIST (\Subscribed) "/" "baz2/bar22" 2781 S: * LIST (\Subscribed) "/" "baz2/bar222" 2782 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2783 S: * LIST (\Subscribed) "/" "eps2/mamba" 2784 S: * LIST (\Subscribed) "/" "qux2/bar2" 2785 S: D03 OK done 2787 The LIST responses for mailboxes "foo2", "baz2", and "eps2" 2788 still have the CHILDINFO extended data item, even though this 2789 information is redundant and the client can determine it by 2790 itself. 2792 9: The following example shows usage of extended syntax for mailbox 2793 pattern. It also demonstrates that the presence of the 2794 CHILDINFO extended data item doesn't necessarily imply 2795 \HasChildren. 2797 C: a1 LIST "" ("foo") 2798 S: * LIST () "/" foo 2799 S: a1 OK done 2801 C: a2 LIST (SUBSCRIBED) "" "foo/*" 2802 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 2803 S: a2 OK done 2805 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN (CHILDREN) 2806 S: * LIST (\HasNoChildren) "/" foo ("CHILDINFO" ("SUBSCRIBED")) 2807 S: a3 OK done 2809 10: The following example shows how a server that supports missing 2810 mailbox hierarchy elements can signal to a client that didn't 2811 specify the RECURSIVEMATCH selection option that there is a 2812 child mailbox that matches the selection criteria. 2814 C: a1 LIST (REMOTE) "" * 2815 S: * LIST () "/" music/rock 2816 S: * LIST (\Remote) "/" also/jazz 2817 S: a1 OK done 2819 C: a2 LIST () "" % 2820 S: * LIST (\NonExistent \HasChildren) "/" music 2821 S: a2 OK done 2823 C: a3 LIST (REMOTE) "" % 2824 S: * LIST (\NonExistent \HasChildren) "/" music 2825 S: * LIST (\NonExistent \HasChildren) "/" also 2826 S: a3 OK done 2828 C: a3.1 LIST "" (% music/rock) 2829 S: * LIST () "/" music/rock 2830 S: a3.1 OK done 2832 Because "music/rock" is the only mailbox under "music", there's 2833 no need for the server to also return "music". However clients 2834 must handle both cases. 2836 11: The following examples show use of STATUS return option. 2838 C: A01 LIST "" % RETURN (STATUS (MESSAGES UNSEEN)) 2839 S: * LIST () "." "INBOX" 2840 S: * STATUS "INBOX" (MESSAGES 17 UNSEEN 16) 2841 S: * LIST () "." "foo" 2842 S: * STATUS "foo" (MESSAGES 30 UNSEEN 29) 2843 S: * LIST (\NoSelect) "." "bar" 2844 S: A01 OK List completed. 2846 The "bar" mailbox isn't selectable, so it has no STATUS reply. 2848 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (STATUS 2849 (MESSAGES)) 2850 S: * LIST (\Subscribed) "." "INBOX" 2851 S: * STATUS "INBOX" (MESSAGES 17) 2852 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED")) 2853 S: A02 OK List completed. 2855 The LIST reply for "foo" is returned because it has matching 2856 children, but no STATUS reply is returned because "foo" itself 2857 doesn't match the selection criteria. 2859 6.3.10. NAMESPACE Command 2861 Arguments: none 2863 Responses: REQUIRED untagged responses: NAMESPACE 2865 Result: OK - command completed 2866 NO - Can't complete the command 2867 BAD - arguments invalid 2869 The NAMESPACE command causes a single ungagged NAMESPACE response to 2870 be returned. The untagged NAMESPACE response contains the prefix and 2871 hierarchy delimiter to the server's Personal Namespace(s), Other 2872 Users' Namespace(s), and Shared Namespace(s) that the server wishes 2873 to expose. The response will contain a NIL for any namespace class 2874 that is not available. The Namespace-Response-Extensions ABNF non 2875 terminal is defined for extensibility and MAY be included in the 2876 NAMESPACE response. 2878 Example 1: 2880 In this example a server supports a single personal namespace. No 2881 leading prefix is used on personal mailboxes and "/" is the hierarchy 2882 delimiter. 2884 C: A001 NAMESPACE 2885 S: * NAMESPACE (("" "/")) NIL NIL 2886 S: A001 OK NAMESPACE command completed 2888 Example 2: 2890 A user logged on anonymously to a server. No personal mailboxes are 2891 associated with the anonymous user and the user does not have access 2892 to the Other Users' Namespace. No prefix is required to access 2893 shared mailboxes and the hierarchy delimiter is "." 2895 C: A001 NAMESPACE 2896 S: * NAMESPACE NIL NIL (("" ".")) 2897 S: A001 OK NAMESPACE command completed 2899 Example 3: 2901 A server that contains a Personal Namespace and a single Shared 2902 Namespace. 2904 C: A001 NAMESPACE 2905 S: * NAMESPACE (("" "/")) NIL (("Public Folders/" "/")) 2906 S: A001 OK NAMESPACE command completed 2908 Example 4: 2910 A server that contains a Personal Namespace, Other Users' Namespace 2911 and multiple Shared Namespaces. Note that the hierarchy delimiter 2912 used within each namespace can be different. 2914 C: A001 NAMESPACE 2915 S: * NAMESPACE (("" "/")) (("~" "/")) (("#shared/" "/") 2916 ("#public/" "/")("#ftp/" "/")("#news." ".")) 2917 S: A001 OK NAMESPACE command completed 2919 The prefix string allows a client to do things such as automatically 2920 creating personal mailboxes or LISTing all available mailboxes within 2921 a namespace. 2923 Example 5: 2925 A server that supports only the Personal Namespace, with a leading 2926 prefix of INBOX to personal mailboxes and a hierarchy delimiter of 2927 "." 2928 C: A001 NAMESPACE 2929 S: * NAMESPACE (("INBOX." ".")) NIL NIL 2930 S: A001 OK NAMESPACE command completed 2932 < Automatically create a mailbox to store sent items.> 2934 C: A002 CREATE "INBOX.Sent Mail" 2935 S: A002 OK CREATE command completed 2937 Although typically a server will support only a single Personal 2938 Namespace, and a single Other User's Namespace, circumstances exist 2939 where there MAY be multiples of these, and a client MUST be prepared 2940 for them. If a client is configured such that it is required to 2941 create a certain mailbox, there can be circumstances where it is 2942 unclear which Personal Namespaces it should create the mailbox in. 2943 In these situations a client SHOULD let the user select which 2944 namespaces to create the mailbox in or just use the first personal 2945 namespace. 2947 Example 6: 2949 In this example, a server supports 2 Personal Namespaces. In 2950 addition to the regular Personal Namespace, the user has an 2951 additional personal namespace to allow access to mailboxes in an MH 2952 format mailstore. 2954 The client is configured to save a copy of all mail sent by the user 2955 into a mailbox called 'Sent Mail'. Furthermore, after a message is 2956 deleted from a mailbox, the client is configured to move that message 2957 to a mailbox called 'Deleted Items'. 2959 Note that this example demonstrates how some extension flags can be 2960 passed to further describe the #mh namespace. 2962 C: A001 NAMESPACE 2963 S: * NAMESPACE (("" "/")("#mh/" "/" "X-PARAM" 2964 ("FLAG1" "FLAG2"))) NIL NIL 2965 S: A001 OK NAMESPACE command completed 2967 < It is desired to keep only one copy of sent mail. 2968 It is unclear which Personal Namespace the client 2969 should use to create the 'Sent Mail' mailbox. 2970 The user is prompted to select a namespace and only 2971 one 'Sent Mail' mailbox is created. > 2973 C: A002 CREATE "Sent Mail" 2974 S: A002 OK CREATE command completed 2976 < The client is designed so that it keeps two 2977 'Deleted Items' mailboxes, one for each namespace. > 2979 C: A003 CREATE "Delete Items" 2980 S: A003 OK CREATE command completed 2982 C: A004 CREATE "#mh/Deleted Items" 2983 S: A004 OK CREATE command completed 2985 The next level of hierarchy following the Other Users' Namespace 2986 prefix SHOULD consist of , where is a user name 2987 as per the LOGIN or AUTHENTICATE command. 2989 A client can construct a LIST command by appending a "%" to the Other 2990 Users' Namespace prefix to discover the Personal Namespaces of other 2991 users that are available to the currently authenticated user. 2993 In response to such a LIST command, a server SHOULD NOT return user 2994 names that have not granted access to their personal mailboxes to the 2995 user in question. 2997 A server MAY return a LIST response containing only the names of 2998 users that have explicitly granted access to the user in question. 3000 Alternatively, a server MAY return NO to such a LIST command, 3001 requiring that a user name be included with the Other Users' 3002 Namespace prefix before listing any other user's mailboxes. 3004 Example 7: 3006 A server that supports providing a list of other user's mailboxes 3007 that are accessible to the currently logged on user. 3009 C: A001 NAMESPACE 3010 S: * NAMESPACE (("" "/")) (("Other Users/" "/")) NIL 3011 S: A001 OK NAMESPACE command completed 3013 C: A002 LIST "" "Other Users/%" 3014 S: * LIST () "/" "Other Users/Mike" 3015 S: * LIST () "/" "Other Users/Karen" 3016 S: * LIST () "/" "Other Users/Matthew" 3017 S: * LIST () "/" "Other Users/Tesa" 3018 S: A002 OK LIST command completed 3020 Example 8: 3022 A server that does not support providing a list of other user's 3023 mailboxes that are accessible to the currently logged on user. The 3024 mailboxes are listable if the client includes the name of the other 3025 user with the Other Users' Namespace prefix. 3027 C: A001 NAMESPACE 3028 S: * NAMESPACE (("" "/")) (("#Users/" "/")) NIL 3029 S: A001 OK NAMESPACE command completed 3031 < In this example, the currently logged on user has access to 3032 the Personal Namespace of user Mike, but the server chose to 3033 suppress this information in the LIST response. However, 3034 by appending the user name Mike (received through user input) 3035 to the Other Users' Namespace prefix, the client is able 3036 to get a listing of the personal mailboxes of user Mike. > 3038 C: A002 LIST "" "#Users/%" 3039 S: A002 NO The requested item could not be found. 3041 C: A003 LIST "" "#Users/Mike/%" 3042 S: * LIST () "/" "#Users/Mike/INBOX" 3043 S: * LIST () "/" "#Users/Mike/Foo" 3044 S: A003 OK LIST command completed. 3046 A prefix string might not contain a hierarchy delimiter, because in 3047 some cases it is not needed as part of the prefix. 3049 Example 9: 3051 A server that allows access to the Other Users' Namespace by 3052 prefixing the others' mailboxes with a '~' followed by , 3053 where is a user name as per the LOGIN or AUTHENTICATE 3054 command. 3056 C: A001 NAMESPACE 3057 S: * NAMESPACE (("" "/")) (("~" "/")) NIL 3058 S: A001 OK NAMESPACE command completed 3060 < List the mailboxes for user mark > 3062 C: A002 LIST "" "~mark/%" 3063 S: * LIST () "/" "~mark/INBOX" 3064 S: * LIST () "/" "~mark/foo" 3065 S: A002 OK LIST command completed 3067 6.3.11. STATUS Command 3069 Arguments: mailbox name 3070 status data item names 3072 Responses: REQUIRED untagged responses: STATUS 3074 Result: OK - status completed 3075 NO - status failure: no status for that name 3076 BAD - command unknown or arguments invalid 3078 The STATUS command requests the status of the indicated mailbox. It 3079 does not change the currently selected mailbox, nor does it affect 3080 the state of any messages in the queried mailbox. 3082 The STATUS command provides an alternative to opening a second 3083 IMAP4rev2 connection and doing an EXAMINE command on a mailbox to 3084 query that mailbox's status without deselecting the current mailbox 3085 in the first IMAP4rev2 connection. 3087 Unlike the LIST command, the STATUS command is not guaranteed to be 3088 fast in its response. Under certain circumstances, it can be quite 3089 slow. In some implementations, the server is obliged to open the 3090 mailbox read-only internally to obtain certain status information. 3091 Also unlike the LIST command, the STATUS command does not accept 3092 wildcards. 3094 Note: The STATUS command is intended to access the status of 3095 mailboxes other than the currently selected mailbox. Because the 3096 STATUS command can cause the mailbox to be opened internally, and 3097 because this information is available by other means on the 3098 selected mailbox, the STATUS command SHOULD NOT be used on the 3099 currently selected mailbox. However, servers MUST be able to 3100 execute STATUS command on the selected mailbox. (This might also 3101 implicitly happen when STATUS return option is used in a LIST 3102 command). 3104 The STATUS command MUST NOT be used as a "check for new messages 3105 in the selected mailbox" operation (refer to sections Section 7, 3106 Section 7.3.1 for more information about the proper method for new 3107 message checking). 3109 STATUS SIZE (see below) can take a significant amount of time, 3110 depending upon server implementation. Clients should use STATUS 3111 SIZE cautiously. 3113 The currently defined status data items that can be requested are: 3115 MESSAGES The number of messages in the mailbox. 3117 UIDNEXT The next unique identifier value of the mailbox. Refer to 3118 Section 2.3.1.1 for more information. 3120 UIDVALIDITY The unique identifier validity value of the mailbox. 3121 Refer to Section 2.3.1.1 for more information. 3123 UNSEEN The number of messages which do not have the \Seen flag set. 3125 DELETED The number of messages which have the \Deleted flag set. 3127 SIZE The total size of the mailbox in octets. This is not strictly 3128 required to be an exact value, but it MUST be equal to or greater 3129 than the sum of the values of the RFC822.SIZE FETCH message data 3130 items (see Section 6.4.5) of all messages in the mailbox. 3132 Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES) 3133 S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 3134 S: A042 OK STATUS completed 3136 6.3.12. APPEND Command 3138 Arguments: mailbox name 3139 OPTIONAL flag parenthesized list 3140 OPTIONAL date/time string 3141 message literal 3143 Responses: no specific responses for this command 3145 Result: OK - append completed 3146 NO - append error: can't append to that mailbox, error 3147 in flags or date/time or message text 3148 BAD - command unknown or arguments invalid 3150 The APPEND command appends the literal argument as a new message to 3151 the end of the specified destination mailbox. This argument SHOULD 3152 be in the format of an [RFC-5322] or [I18N-HDRS] message. 8-bit 3153 characters are permitted in the message. A server implementation 3154 that is unable to preserve 8-bit data properly MUST be able to 3155 reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB] 3156 content transfer encoding. 3158 Note: There may be exceptions, e.g., draft messages, in which 3159 required [RFC-5322] header lines are omitted in the message 3160 literal argument to APPEND. The full implications of doing so 3161 must be understood and carefully weighed. 3163 If a flag parenthesized list is specified, the flags SHOULD be set in 3164 the resulting message; otherwise, the flag list of the resulting 3165 message is set to empty by default. 3167 If a date-time is specified, the internal date SHOULD be set in the 3168 resulting message; otherwise, the internal date of the resulting 3169 message is set to the current date and time by default. 3171 If the append is unsuccessful for any reason, the mailbox MUST be 3172 restored to its state before the APPEND attempt (other than possibly 3173 keeping the changed mailbox's UIDNEXT value); no partial appending is 3174 permitted. 3176 If the destination mailbox does not exist, a server MUST return an 3177 error, and MUST NOT automatically create the mailbox. Unless it is 3178 certain that the destination mailbox can not be created, the server 3179 MUST send the response code "[TRYCREATE]" as the prefix of the text 3180 of the tagged NO response. This gives a hint to the client that it 3181 can attempt a CREATE command and retry the APPEND if the CREATE is 3182 successful. 3184 On successful completion of an APPEND, the server SHOULD return an 3185 APPENDUID response code. 3187 In the case of a mailbox that has permissions set so that the client 3188 can APPEND to the mailbox, but not SELECT or EXAMINE it, the server 3189 SHOULD NOT send an APPENDUID response code as it would disclose 3190 information about the mailbox. 3192 In the case of a mailbox that has UIDNOTSTICKY status (see 3193 UIDNOTSTICKY response code definition), the server MAY omit the 3194 APPENDUID response code as it is not meaningful. 3196 If the server does not return the APPENDUID response codes, the 3197 client can discover this information by selecting the destination 3198 mailbox. The location of messages placed in the destination mailbox 3199 by APPEND can be determined by using FETCH and/or SEARCH commands 3200 (e.g., for Message-ID or some unique marker placed in the message in 3201 an APPEND). 3203 If the mailbox is currently selected, the normal new message actions 3204 SHOULD occur. Specifically, the server SHOULD notify the client 3205 immediately via an untagged EXISTS response. If the server does not 3206 do so, the client MAY issue a NOOP command after one or more APPEND 3207 commands. 3209 Example: C: A003 APPEND saved-messages (\Seen) {310} 3210 S: + Ready for literal data 3211 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3212 C: From: Fred Foobar 3213 C: Subject: afternoon meeting 3214 C: To: mooch@owatagu.siam.edu 3215 C: Message-Id: 3216 C: MIME-Version: 1.0 3217 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3218 C: 3219 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3220 C: 3221 S: A003 OK APPEND completed 3223 Example: C: A003 APPEND saved-messages (\Seen) {297} 3224 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3225 C: From: Fred Foobar 3226 C: Subject: afternoon meeting 3227 C: To: mooch@example.com 3228 C: Message-Id: 3229 C: MIME-Version: 1.0 3230 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3231 C: 3232 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3233 C: 3234 S: A003 OK [APPENDUID 38505 3955] APPEND completed 3235 C: A004 COPY 2:4 meeting 3236 S: A004 OK [COPYUID 38505 304,319:320 3956:3958] Done 3237 C: A005 UID COPY 305:310 meeting 3238 S: A005 OK No matching messages, so nothing copied 3239 C: A006 COPY 2 funny 3240 S: A006 OK Done 3241 C: A007 SELECT funny 3242 S: * 1 EXISTS 3243 S: * OK [UIDVALIDITY 3857529045] Validity session-only 3244 S: * OK [UIDNEXT 2] Predicted next UID 3245 S: * NO [UIDNOTSTICKY] Non-persistent UIDs 3246 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 3247 S: * OK [PERMANENTFLAGS (\Deleted \Seen)] Limited 3248 S: A007 OK [READ-WRITE] SELECT completed 3250 In this example, A003 and A004 demonstrate successful appending and 3251 copying to a mailbox that returns the UIDs assigned to the messages. 3252 A005 is an example in which no messages were copied; this is because 3253 in A003, we see that message 2 had UID 304, and message 3 had UID 3254 319; therefore, UIDs 305 through 310 do not exist (refer to 3255 Section 2.3.1.1 for further explanation). A006 is an example of a 3256 message being copied that did not return a COPYUID; and, as expected, 3257 A007 shows that the mail store containing that mailbox does not 3258 support persistent UIDs. 3260 Note: The APPEND command is not used for message delivery, because 3261 it does not provide a mechanism to transfer [SMTP] envelope 3262 information. 3264 6.3.13. IDLE Command 3266 Arguments: none 3268 Responses: continuation data will be requested; the client sends the 3269 continuation data "DONE" to end the command 3271 Result: OK - IDLE completed after client sent "DONE" 3272 NO - failure: the server will not allow the IDLE command 3273 at this time 3274 BAD - command unknown or arguments invalid 3276 Without the IDLE command a client requires to poll the server for 3277 changes to the selected mailbox (new mail, deletions, flag changes). 3278 It's often more desirable to have the server transmit updates to the 3279 client in real time. This allows a user to see new mail immediately. 3280 The IDLE command allows a client to tell the server that it's ready 3281 to accept such real-time updates. 3283 The IDLE command is sent from the client to the server when the 3284 client is ready to accept unsolicited update messages. The server 3285 requests a response to the IDLE command using the continuation ("+") 3286 response. The IDLE command remains active until the client responds 3287 to the continuation, and as long as an IDLE command is active, the 3288 server is now free to send untagged EXISTS, EXPUNGE, FETCH, and other 3289 responses at any time. If the server choose to send unsolicited 3290 FETCH responses, they MUST include UID FETCH item. 3292 The IDLE command is terminated by the receipt of a "DONE" 3293 continuation from the client; such response satisfies the server's 3294 continuation request. At that point, the server MAY send any 3295 remaining queued untagged responses and then MUST immediately send 3296 the tagged response to the IDLE command and prepare to process other 3297 commands. As for other commands, the processing of any new command 3298 may cause the sending of unsolicited untagged responses, subject to 3299 the ambiguity limitations. The client MUST NOT send a command while 3300 the server is waiting for the DONE, since the server will not be able 3301 to distinguish a command from a continuation. 3303 The server MAY consider a client inactive if it has an IDLE command 3304 running, and if such a server has an inactivity timeout it MAY log 3305 the client off implicitly at the end of its timeout period. Because 3306 of that, clients using IDLE are advised to terminate the IDLE and re- 3307 issue it at least every 29 minutes to avoid being logged off. This 3308 still allows a client to receive immediate mailbox updates even 3309 though it need only "poll" at half hour intervals. 3311 Example: C: A001 SELECT INBOX 3312 S: * FLAGS (\Deleted \Seen \Flagged) 3313 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Flagged)] Limited 3314 S: * 3 EXISTS 3315 S: * OK [UIDVALIDITY 1] 3316 S: A001 OK [READ-WRITE] SELECT completed 3317 C: A002 IDLE 3318 S: + idling 3319 ...time passes; new mail arrives... 3320 S: * 4 EXISTS 3321 C: DONE 3322 S: A002 OK IDLE terminated 3323 ...another client expunges message 2 now... 3324 C: A003 FETCH 4 ALL 3325 S: * 4 FETCH (...) 3326 S: A003 OK FETCH completed 3327 C: A004 IDLE 3328 S: * 2 EXPUNGE 3329 S: * 3 EXISTS 3330 S: + idling 3331 ...time passes; another client expunges message 3... 3332 S: * 3 EXPUNGE 3333 S: * 2 EXISTS 3334 ...time passes; new mail arrives... 3335 S: * 3 EXISTS 3336 C: DONE 3337 S: A004 OK IDLE terminated 3338 C: A005 FETCH 3 ALL 3339 S: * 3 FETCH (...) 3340 S: A005 OK FETCH completed 3341 C: A006 IDLE 3343 6.4. Client Commands - Selected State 3345 In the selected state, commands that manipulate messages in a mailbox 3346 are permitted. 3348 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 3349 and the authenticated state commands (SELECT, EXAMINE, NAMESPACE, 3350 CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, STATUS, and 3351 APPEND), the following commands are valid in the selected state: 3352 CLOSE, UNSELECT, EXPUNGE, SEARCH, FETCH, STORE, COPY, MOVE, and UID. 3354 6.4.1. CLOSE Command 3356 Arguments: none 3358 Responses: no specific responses for this command 3359 Result: OK - close completed, now in authenticated state 3360 BAD - command unknown or arguments invalid 3362 The CLOSE command permanently removes all messages that have the 3363 \Deleted flag set from the currently selected mailbox, and returns to 3364 the authenticated state from the selected state. No untagged EXPUNGE 3365 responses are sent. 3367 No messages are removed, and no error is given, if the mailbox is 3368 selected by an EXAMINE command or is otherwise selected read-only. 3370 Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT command 3371 MAY be issued without previously issuing a CLOSE command. The 3372 SELECT, EXAMINE, and LOGOUT commands implicitly close the currently 3373 selected mailbox without doing an expunge. However, when many 3374 messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT sequence is 3375 considerably faster than an EXPUNGE-LOGOUT or EXPUNGE-SELECT because 3376 no untagged EXPUNGE responses (which the client would probably 3377 ignore) are sent. 3379 Example: C: A341 CLOSE 3380 S: A341 OK CLOSE completed 3382 6.4.2. UNSELECT Command 3384 Arguments: none 3386 Responses: no specific responses for this command 3388 Result: OK - unselect completed, now in authenticated state 3389 BAD - no mailbox selected, or argument supplied but none 3390 permitted 3392 The UNSELECT command frees server's resources associated with the 3393 selected mailbox and returns the server to the authenticated state. 3394 This command performs the same actions as CLOSE, except that no 3395 messages are permanently removed from the currently selected mailbox. 3397 Example: C: A342 UNSELECT 3398 S: A342 OK Unselect completed 3400 6.4.3. EXPUNGE Command 3402 Arguments: none 3404 Responses: untagged responses: EXPUNGE 3406 Result: OK - expunge completed 3407 NO - expunge failure: can't expunge (e.g., permission 3408 denied) 3409 BAD - command unknown or arguments invalid 3411 The EXPUNGE command permanently removes all messages that have the 3412 \Deleted flag set from the currently selected mailbox. Before 3413 returning an OK to the client, an untagged EXPUNGE response is sent 3414 for each message that is removed. 3416 Example: C: A202 EXPUNGE 3417 S: * 3 EXPUNGE 3418 S: * 3 EXPUNGE 3419 S: * 5 EXPUNGE 3420 S: * 8 EXPUNGE 3421 S: A202 OK EXPUNGE completed 3423 Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag 3424 set. See the description of the EXPUNGE response for further 3425 explanation. 3427 6.4.4. SEARCH Command 3429 Arguments: OPTIONAL result specifier 3430 OPTIONAL [CHARSET] specification 3431 searching criteria (one or more) 3433 Responses: OPTIONAL untagged response: ESEARCH 3435 Result: OK - search completed 3436 NO - search error: can't search that [CHARSET] or 3437 criteria 3438 BAD - command unknown or arguments invalid 3440 The SEARCH command searches the mailbox for messages that match the 3441 given searching criteria. 3443 The SEARCH command may contain result options. Result options 3444 control what kind of information is returned about messages matching 3445 the search criteria in an untagged ESEARCH response. If no result 3446 option is specified or empty list of options is specified "()", ALL 3447 is assumed (see below). The order of individual options is 3448 arbitrary. Individual options may contain parameters enclosed in 3449 parentheses (*). If an option has parameters, they consist of atoms 3450 and/or strings and/or lists in a specific order. Any options not 3451 defined by extensions that the server supports must be rejected with 3452 a BAD response. 3454 (*) - if an option has a mandatory parameter, which can always be 3455 represented as a number or a sequence-set, the option parameter does 3456 not need the enclosing (). See the ABNF for more details. 3458 This document specifies the following result options: 3460 MIN 3462 Return the lowest message number/UID that satisfies the SEARCH 3463 criteria. 3465 If the SEARCH results in no matches, the server MUST NOT 3466 include the MIN result option in the ESEARCH response; however, 3467 it still MUST send the ESEARCH response. 3469 MAX 3471 Return the highest message number/UID that satisfies the SEARCH 3472 criteria. 3474 If the SEARCH results in no matches, the server MUST NOT 3475 include the MAX result option in the ESEARCH response; however, 3476 it still MUST send the ESEARCH response. 3478 ALL 3480 Return all message numbers/UIDs that satisfy the SEARCH 3481 criteria using the sequence-set syntax. Note, the client MUST 3482 NOT assume that messages/UIDs will be listed in any particular 3483 order. 3485 If the SEARCH results in no matches, the server MUST NOT 3486 include the ALL result option in the ESEARCH response; however, 3487 it still MUST send the ESEARCH response. 3489 COUNT Return number of the messages that satisfy the SEARCH 3490 criteria. This result option MUST always be included in the 3491 ESEARCH response. 3493 SAVE 3495 This option tells the server to remember the result of the 3496 SEARCH or UID SEARCH command (as well as any command based on 3497 SEARCH, e.g., SORT and THREAD [RFC5256]>) and store it in an 3498 internal variable that we will reference as the "search result 3499 variable". The client can use the "$" marker to reference the 3500 content of this internal variable. The "$" marker can be used 3501 instead of message sequence or UID sequence in order to 3502 indicate that the server should substitute it with the list of 3503 messages from the search result variable. Thus, the client can 3504 use the result of the latest remembered SEARCH command as a 3505 parameter to another command. See Section 6.4.4.1 for details 3506 on how the value of the search result variable is determined, 3507 how it is affected by other commands executed, and how SAVE 3508 return option interacts with other return options. 3510 In absence of any other SEARCH result option, the SAVE result 3511 option also suppresses any ESEARCH response that would have 3512 been otherwise returned by the SEARCH command. 3514 Note: future extensions to this document can allow servers to return 3515 multiple ESEARCH responses for a single extended SEARCH command. 3516 However all options specified above MUST result in a single ESEARCH 3517 response. These extensions will have to describe how results from 3518 multiple ESEARCH responses are to be amalgamated. 3520 Searching criteria consist of one or more search keys. 3522 When multiple keys are specified, the result is the intersection (AND 3523 function) of all the messages that match those keys. For example, 3524 the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers to all 3525 deleted messages from Smith with INTERNALDATE greater than February 3526 1, 1994. A search key can also be a parenthesized list of one or 3527 more search keys (e.g., for use with the OR and NOT keys). 3529 Server implementations MAY exclude [MIME-IMB] body parts with 3530 terminal content media types other than TEXT and MESSAGE from 3531 consideration in SEARCH matching. 3533 The OPTIONAL [CHARSET] specification consists of the word "CHARSET" 3534 followed by a registered [CHARSET] [CHARSET-REG]. It indicates the 3535 [CHARSET] of the strings that appear in the search criteria. 3536 [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in 3537 [RFC-5322]/[MIME-IMB] headers, MUST be decoded before comparing text. 3538 Servers MUST support US-ASCII and UTF-8 charsets; other [CHARSET]s 3539 MAY be supported. Clients SHOULD use UTF-8. Note that if "CHARSET" 3540 is not provided IMAP4rev2 server MUST assume UTF-8, so selecting 3541 CHARSET UTF-8 is redundant. It is permitted for improved 3542 compatibility with existing IMAP4rev1 clients. 3544 If the server does not support the specified [CHARSET], it MUST 3545 return a tagged NO response (not a BAD). This response SHOULD 3546 contain the BADCHARSET response code, which MAY list the [CHARSET]s 3547 supported by the server. 3549 In all search keys that use strings and unless specified otherwise, a 3550 message matches the key if the string is a substring of the 3551 associated text. The matching SHOULD be case-insensitive for 3552 characters within ASCII range. Consider using [IMAP-I18N] for 3553 language-sensitive case-insensitive searching. Note that the empty 3554 string is a substring; this is useful when doing a HEADER search in 3555 order to test for a header field presence in the message. 3557 The defined search keys are as follows. Refer to the Formal Syntax 3558 section for the precise syntactic definitions of the arguments. 3560 Messages with message sequence numbers corresponding 3561 to the specified message sequence number set. 3563 ALL All messages in the mailbox; the default initial key for ANDing. 3565 ANSWERED Messages with the \Answered flag set. 3567 BCC Messages that contain the specified string in the 3568 envelope structure's BCC field. 3570 BEFORE Messages whose internal date (disregarding time and 3571 timezone) is earlier than the specified date. 3573 BODY Messages that contain the specified string in the body 3574 of the message. Unlike TEXT (see below), this doesn't match any 3575 header fields. Servers are allowed to implement flexible matching 3576 for this search key, for example matching "swim" to both "swam" 3577 and "swum" in English language text or only doing full word 3578 matching (where "swim" will not match "swimming"). 3580 CC Messages that contain the specified string in the 3581 envelope structure's CC field. 3583 DELETED Messages with the \Deleted flag set. 3585 DRAFT Messages with the \Draft flag set. 3587 FLAGGED Messages with the \Flagged flag set. 3589 FROM Messages that contain the specified string in the 3590 envelope structure's FROM field. 3592 HEADER Messages that have a header with the 3593 specified field-name (as defined in [RFC-5322]) and that contains 3594 the specified string in the text of the header (what comes after 3595 the colon). If the string to search is zero-length, this matches 3596 all messages that have a header line with the specified field-name 3597 regardless of the contents. Servers should use substring search 3598 for this SEARCH item, as clients can use it for automatic 3599 processing not initiated by end users. For example this can be 3600 used for searching for Message-ID or Content-Type header field 3601 values that need to be exact, or for searches in header fields 3602 that the IMAP server might not know anything about. 3604 KEYWORD Messages with the specified keyword flag set. 3606 LARGER Messages with an [RFC-5322] size larger than the 3607 specified number of octets. 3609 NOT Messages that do not match the specified search 3610 key. 3612 ON Messages whose internal date (disregarding time and 3613 timezone) is within the specified date. 3615 OR Messages that match either search 3616 key. 3618 SEEN Messages that have the \Seen flag set. 3620 SENTBEFORE Messages whose [RFC-5322] Date: header 3621 (disregarding time and timezone) is earlier than the specified 3622 date. 3624 SENTON Messages whose [RFC-5322] Date: header (disregarding 3625 time and timezone) is within the specified date. 3627 SENTSINCE Messages whose [RFC-5322] Date: header 3628 (disregarding time and timezone) is within or later than the 3629 specified date. 3631 SINCE Messages whose internal date (disregarding time and 3632 timezone) is within or later than the specified date. 3634 SMALLER Messages with an [RFC-5322] size smaller than the 3635 specified number of octets. 3637 SUBJECT Messages that contain the specified string in the 3638 envelope structure's SUBJECT field. 3640 TEXT Messages that contain the specified string in the 3641 header (including MIME header fields) or body of the message. 3642 Servers are allowed to implement flexible matching for this search 3643 key, for example matching "swim" to both "swam" and "swum" in 3644 English language text or only doing full word matching (where 3645 "swim" will not match "swimming"). 3647 TO Messages that contain the specified string in the 3648 envelope structure's TO field. 3650 UID Messages with unique identifiers corresponding to 3651 the specified unique identifier set. Sequence set ranges are 3652 permitted. 3654 UNANSWERED Messages that do not have the \Answered flag set. 3656 UNDELETED Messages that do not have the \Deleted flag set. 3658 UNDRAFT Messages that do not have the \Draft flag set. 3660 UNFLAGGED Messages that do not have the \Flagged flag set. 3662 UNKEYWORD Messages that do not have the specified keyword 3663 flag set. 3665 UNSEEN Messages that do not have the \Seen flag set. 3667 Example: C: A282 SEARCH RETURN (MIN COUNT) FLAGGED 3668 SINCE 1-Feb-1994 NOT FROM "Smith" 3669 S: * ESEARCH (TAG "A282") MIN 2 COUNT 3 3670 S: A282 OK SEARCH completed 3672 Example: C: A283 SEARCH RETURN () FLAGGED 3673 SINCE 1-Feb-1994 NOT FROM "Smith" 3674 S: * ESEARCH (TAG "A283") ALL 2,10:11 3675 S: A283 OK SEARCH completed 3677 Example: C: A284 SEARCH TEXT "string not in mailbox" 3678 S: * ESEARCH (TAG "A284") 3679 S: A284 OK SEARCH completed 3680 C: A285 SEARCH CHARSET UTF-8 TEXT {6} 3681 S: + Ready for literal text 3682 C: XXXXXX 3683 S: * ESEARCH (TAG "A285") ALL 43 3684 S: A285 OK SEARCH completed 3686 Note: Since this document is restricted to 7-bit ASCII text, it is 3687 not possible to show actual UTF-8 data. The "XXXXXX" is a 3688 placeholder for what would be 6 octets of 8-bit data in an actual 3689 transaction. 3691 The following example demonstrates finding the first unseen message 3692 in the mailbox: 3694 Example: C: A284 SEARCH RETURN (MIN) UNSEEN 3695 S: * ESEARCH (TAG "A284") MIN 4 3696 S: A284 OK SEARCH completed 3698 The following example demonstrates that if the ESEARCH UID indicator 3699 is present, all data in the ESEARCH response is referring to UIDs; 3700 for example, the MIN result specifier will be followed by a UID. 3702 Example: C: A285 UID SEARCH RETURN (MIN MAX) 1:5000 3703 S: * ESEARCH (TAG "A285") UID MIN 7 MAX 3800 3704 S: A285 OK SEARCH completed 3706 The following example demonstrates returning the number of deleted 3707 messages: 3709 Example: C: A286 SEARCH RETURN (COUNT) DELETED 3710 S: * ESEARCH (TAG "A286") COUNT 15 3711 S: A286 OK SEARCH completed 3713 6.4.4.1. SAVE result option and SEARCH result variable 3715 Upon successful completion of a SELECT or an EXAMINE command (after 3716 the tagged OK response), the current search result variable is reset 3717 to the empty sequence. 3719 A successful SEARCH command with the SAVE result option sets the 3720 value of the search result variable to the list of messages found in 3721 the SEARCH command. For example, if no messages were found, the 3722 search result variable will contain the empty sequence. 3724 Any of the following SEARCH commands MUST NOT change the search 3725 result variable: 3727 a SEARCH command that caused the server to return the BAD tagged 3728 response, 3730 a SEARCH command with no SAVE result option that caused the server 3731 to return NO tagged response, 3733 a successful SEARCH command with no SAVE result option. 3735 A SEARCH command with the SAVE result option that caused the server 3736 to return the NO tagged response sets the value of the search result 3737 variable to the empty sequence. 3739 When a message listed in the search result variable is EXPUNGEd, it 3740 is automatically removed from the list. Implementors are reminded 3741 that if the server stores the list as a list of message numbers, it 3742 MUST automatically adjust them when notifying the client about 3743 expunged messages, as described in Section 7.4.1. 3745 If the server decides to send a new UIDVALIDITY value while the 3746 mailbox is opened, this causes resetting of the search variable to 3747 the empty sequence. 3749 Note that even if the "$" marker contains the empty sequence of 3750 messages, it must be treated by all commands accepting message sets 3751 as parameters as a valid, but non-matching list of messages. For 3752 example, the "FETCH $" command would return a tagged OK response and 3753 no FETCH responses. See also the Example 5 in Section 6.4.4.4. 3755 The SAVE result option doesn't change whether the server would return 3756 items corresponding to MIN, MAX, ALL, or COUNT result options. 3758 When the SAVE result option is combined with the MIN or MAX result 3759 option, and both ALL and COUNT result options are absent, the 3760 corresponding MIN/MAX is returned (if the search result is not 3761 empty), but the "$" marker would contain a single message as returned 3762 in the MIN/MAX return item. 3764 If the SAVE result option is combined with both MIN and MAX result 3765 options, and both ALL and COUNT result options are absent, the "$" 3766 marker would contain zero, one or two messages as returned in the 3767 MIN/MAX return items. 3769 If the SAVE result option is combined with the ALL and/or COUNT 3770 result option(s), the "$" marker would always contain all messages 3771 found by the SEARCH or UID SEARCH command. 3773 The following table summarizes the additional requirement on ESEARCH 3774 server implementations described in this section. 3776 +------------------------------+--------------------+ 3777 | Combination of Result option | "$" marker value | 3778 +------------------------------+--------------------+ 3779 | SAVE MIN | MIN | 3780 | SAVE MAX | MAX | 3781 | SAVE MIN MAX | MIN & MAX | 3782 | SAVE * [m] | all found messages | 3783 +------------------------------+--------------------+ 3785 where '*' means "ALL" and/or "COUNT", and '[m]' means optional "MIN" 3786 and/or "MAX" 3788 Implementation note: server implementors should note that "$" can 3789 reference IMAP message sequences or UID sequences, depending on the 3790 context where it is used. For example, the "$" marker can be set as 3791 a result of a SEARCH (SAVE) command and used as a parameter to a UID 3792 FETCH command (which accepts a UID sequence, not a message sequence), 3793 or the "$" marker can be set as a result of a UID SEARCH (SAVE) 3794 command and used as a parameter to a FETCH command (which accepts a 3795 message sequence, not a UID sequence). Server implementations need 3796 to automatically map the "$" marker value to message numbers or UIDs, 3797 depending on context where the "$" marker is used. 3799 6.4.4.2. Multiple Commands in Progress 3801 Use of a SEARCH RETURN (SAVE) command followed by a command using the 3802 "$" marker creates direct dependency between the two commands. As 3803 directed by Section 5.5, a server MUST execute the two commands in 3804 the order they were received. 3806 A client MAY pipeline a SEARCH RETURN (SAVE) command with one or more 3807 command using the "$" marker, as long as this doesn't create an 3808 ambiguity, as described in by Section 5.5. Examples 7-9 in 3809 Section 6.4.4.4 explain this in more details. 3811 6.4.4.3. Refusing to Save Search Results 3813 In some cases, the server MAY refuse to save a SEARCH (SAVE) result, 3814 for example, if an internal limit on the number of saved results is 3815 reached. In this case, the server MUST return a tagged NO response 3816 containing the NOTSAVED response code and set the search result 3817 variable to the empty sequence, as described in Section 6.4.4.1. 3819 6.4.4.4. Examples showing use of SAVE result option 3821 Only in this section: explanatory comments in examples that start 3822 with // are not part of the protocol. 3824 1) The following example demonstrates how the client can use the 3825 result of a SEARCH command to FETCH headers of interesting messages: 3827 Example 1: 3828 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3829 NOT FROM "Smith" 3830 S: A282 OK SEARCH completed, result saved 3831 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3832 S: * 2 FETCH (UID 14 ... 3833 S: * 84 FETCH (UID 100 ... 3834 S: * 882 FETCH (UID 1115 ... 3835 S: A283 OK completed 3837 The client can also pipeline the two commands: 3839 Example 2: 3840 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3841 NOT FROM "Smith" 3842 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3843 S: A282 OK SEARCH completed 3844 S: * 2 FETCH (UID 14 ... 3845 S: * 84 FETCH (UID 100 ... 3846 S: * 882 FETCH (UID 1115 ... 3847 S: A283 OK completed 3849 2) The following example demonstrates that the result of one SEARCH 3850 command can be used as input to another SEARCH command: 3852 Example 3: 3853 C: A300 SEARCH RETURN (SAVE) SINCE 1-Jan-2004 3854 NOT FROM "Smith" 3855 S: A300 OK SEARCH completed 3856 C: A301 UID SEARCH UID $ SMALLER 4096 3857 S: * ESEARCH (TAG "A301") UID ALL 17,900,901 3858 S: A301 OK completed 3860 Note that the second command in Example 3 can be replaced with: 3861 C: A301 UID SEARCH $ SMALLER 4096 3862 and the result of the command would be the same. 3864 3) The following example shows that the "$" marker can be combined 3865 with other message numbers using the OR SEARCH criterion. 3867 Example 4: 3868 C: P282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3869 NOT FROM "Smith" 3870 S: P282 OK SEARCH completed 3871 C: P283 SEARCH CHARSET UTF-8 (OR $ 1,3000:3021) TEXT {8} 3872 C: YYYYYYYY 3873 S: * ESEARCH (TAG "P283") ALL 882,1102,3003,3005:3006 3874 S: P283 OK completed 3876 Note: Since this document format is restricted to 7-bit ASCII text, 3877 it is not possible to show actual UTF-8 data. The "YYYYYYYY" is a 3878 placeholder for what would be 8 octets of 8-bit data in an actual 3879 transaction. 3881 4) The following example demonstrates that a failed SEARCH sets the 3882 search result variable to the empty list. The server doesn't 3883 implement the KOI8-R charset. 3885 Example 5: 3886 C: B282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3887 NOT FROM "Smith" 3888 S: B282 OK SEARCH completed 3889 C: B283 SEARCH RETURN (SAVE) CHARSET KOI8-R 3890 (OR $ 1,3000:3021) TEXT {4} 3891 C: XXXX 3892 S: B283 NO [BADCHARSET UTF-8] KOI8-R is not supported 3893 //After this command the saved result variable contains 3894 //no messages. A client that wants to reissue the B283 3895 //SEARCH command with another CHARSET would have to reissue 3896 //the B282 command as well. One possible workaround for 3897 //this is to include the desired CHARSET parameter 3898 //in the earliest SEARCH RETURN (SAVE) command in a 3899 //sequence of related SEARCH commands, to cause 3900 //the earliest SEARCH in the sequence to fail. 3901 //A better approach might be to always use CHARSET UTF-8 3902 //instead. 3904 Note: Since this document format is restricted to 7-bit ASCII text, 3905 it is not possible to show actual KOI8-R data. The "XXXX" is a 3906 placeholder for what would be 4 octets of 8-bit data in an actual 3907 transaction. 3909 5) The following example demonstrates that it is not an error to use 3910 the "$" marker when it contains no messages. 3912 Example 6: 3913 C: E282 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3914 NOT FROM "Eric" 3915 C: E283 COPY $ "Other Messages" 3916 //The "$" contains no messages 3917 S: E282 OK SEARCH completed 3918 S: E283 OK COPY completed, nothing copied 3920 Example 7: 3921 C: F282 SEARCH RETURN (SAVE) KEYWORD $Junk 3922 C: F283 COPY $ "Junk" 3923 C: F284 STORE $ +FLAGS.Silent (\Deleted) 3924 S: F282 OK SEARCH completed 3925 S: F283 OK COPY completed 3926 S: F284 OK STORE completed 3928 Example 8: 3929 C: G282 SEARCH RETURN (SAVE) KEYWORD $Junk 3930 C: G283 SEARCH RETURN (ALL) SINCE 28-Oct-2006 3931 FROM "Eric" 3932 // The server can execute the two SEARCH commands 3933 // in any order, as they don't have any dependency. 3934 // For example, it may return: 3935 S: * ESEARCH (TAG "G283") ALL 3:15,27,29:103 3936 S: G283 OK SEARCH completed 3937 S: G282 OK SEARCH completed 3939 The following example demonstrates that the result of the second 3940 SEARCH RETURN (SAVE) always overrides the result of the first. 3942 Example 9: 3943 C: H282 SEARCH RETURN (SAVE) KEYWORD $Junk 3944 C: H283 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3945 FROM "Eric" 3946 S: H282 OK SEARCH completed 3947 S: H283 OK SEARCH completed 3948 // At this point "$" would contain results of H283 3950 The following example demonstrates behavioral difference for 3951 different combinations of ESEARCH result options. 3953 Example 10: 3954 C: C282 SEARCH RETURN (ALL) SINCE 12-Feb-2006 3955 NOT FROM "Smith" 3956 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3957 //$ value hasn't changed 3958 S: C282 OK SEARCH completed 3960 C: C283 SEARCH RETURN (ALL SAVE) SINCE 12-Feb-2006 3961 NOT FROM "Smith" 3962 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3963 //$ value is 2,10:15,21 3964 S: C283 OK SEARCH completed 3966 C: C284 SEARCH RETURN (SAVE MIN) SINCE 12-Feb-2006 3967 NOT FROM "Smith" 3968 S: * ESEARCH (TAG "C284") MIN 2 3969 //$ value is 2 3970 S: C284 OK SEARCH completed 3972 C: C285 SEARCH RETURN (MAX SAVE MIN) SINCE 3973 12-Feb-2006 NOT FROM "Smith" 3974 S: * ESEARCH (TAG "C285") MIN 2 MAX 21 3975 //$ value is 2,21 3976 S: C285 OK SEARCH completed 3978 C: C286 SEARCH RETURN (MAX SAVE MIN COUNT) 3979 SINCE 12-Feb-2006 NOT FROM "Smith" 3980 S: * ESEARCH (TAG "C286") MIN 2 MAX 21 COUNT 8 3981 //$ value is 2,10:15,21 3982 S: C286 OK SEARCH completed 3984 C: C286 SEARCH RETURN (ALL SAVE MIN) SINCE 3985 12-Feb-2006 NOT FROM "Smith" 3986 S: * ESEARCH (TAG "C286") MIN 2 ALL 2,10:15,21 3987 //$ value is 2,10:15,21 3988 S: C286 OK SEARCH completed 3990 6.4.5. FETCH Command 3992 Arguments: sequence set 3993 message data item names or macro 3995 Responses: untagged responses: FETCH 3997 Result: OK - fetch completed 3998 NO - fetch error: can't fetch that data 3999 BAD - command unknown or arguments invalid 4001 The FETCH command retrieves data associated with a message in the 4002 mailbox. The data items to be fetched can be either a single atom or 4003 a parenthesized list. 4005 Most data items, identified in the formal syntax under the msg-att- 4006 static rule, are static and MUST NOT change for any particular 4007 message. Other data items, identified in the formal syntax under the 4008 msg-att-dynamic rule, MAY change, either as a result of a STORE 4009 command or due to external events. 4011 For example, if a client receives an ENVELOPE for a message when 4012 it already knows the envelope, it can safely ignore the newly 4013 transmitted envelope. 4015 There are three macros which specify commonly-used sets of data 4016 items, and can be used instead of data items. A macro must be used 4017 by itself, and not in conjunction with other macros or data items. 4019 ALL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE) 4021 FAST Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE) 4023 FULL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE 4024 BODY) 4026 The currently defined data items that can be fetched are: 4028 BINARY[]<> 4030 Requests that the specified section be transmitted after 4031 performing Content-Transfer-Encoding-related decoding. 4033 The argument, if present, requests that a subset of 4034 the data be returned. The semantics of a partial FETCH BINARY 4035 command are the same as for a partial FETCH BODY command, with 4036 the exception that the arguments refer to the DECODED 4037 section data. 4039 Note that this data item can only be requested for leaf (i.e. 4040 non multipart/*, non message/rfc822 and non message/global) 4041 body parts. 4043 BINARY.PEEK[]<> An alternate form of 4044 BINARY[] that does not implicitly set the \Seen 4045 flag. 4047 BINARY.SIZE[] 4048 Requests the decoded size of the section (i.e., the size to 4049 expect in response to the corresponding FETCH BINARY request). 4051 Note: client authors are cautioned that this might be an 4052 expensive operation for some server implementations. 4053 Needlessly issuing this request could result in degraded 4054 performance due to servers having to calculate the value every 4055 time the request is issued. 4057 Note that this data item can only be requested for leaf (i.e. 4058 non multipart/*, non message/rfc822 and non message/global) 4059 body parts. 4061 BODY Non-extensible form of BODYSTRUCTURE. 4063 BODY[
]<> 4065 The text of a particular body section. The section 4066 specification is a set of zero or more part specifiers 4067 delimited by periods. A part specifier is either a part number 4068 or one of the following: HEADER, HEADER.FIELDS, 4069 HEADER.FIELDS.NOT, MIME, and TEXT. An empty section 4070 specification refers to the entire message, including the 4071 header. 4073 Every message has at least one part number. Non-[MIME-IMB] 4074 messages, and non-multipart [MIME-IMB] messages with no 4075 encapsulated message, only have a part 1. 4077 Multipart messages are assigned consecutive part numbers, as 4078 they occur in the message. If a particular part is of type 4079 message or multipart, its parts MUST be indicated by a period 4080 followed by the part number within that nested multipart part. 4082 A part of type MESSAGE/RFC822 or MESSAGE/GLOBAL also has nested 4083 part numbers, referring to parts of the MESSAGE part's body. 4085 The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part 4086 specifiers can be the sole part specifier or can be prefixed by 4087 one or more numeric part specifiers, provided that the numeric 4088 part specifier refers to a part of type MESSAGE/RFC822 or 4089 MESSAGE/GLOBAL. The MIME part specifier MUST be prefixed by 4090 one or more numeric part specifiers. 4092 The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part 4093 specifiers refer to the [RFC-5322] header of the message or of 4094 an encapsulated [MIME-IMT] MESSAGE/RFC822 or MESSAGE/GLOBAL 4095 message. HEADER.FIELDS and HEADER.FIELDS.NOT are followed by a 4096 list of field-name (as defined in [RFC-5322]) names, and return 4097 a subset of the header. The subset returned by HEADER.FIELDS 4098 contains only those header fields with a field-name that 4099 matches one of the names in the list; similarly, the subset 4100 returned by HEADER.FIELDS.NOT contains only the header fields 4101 with a non-matching field-name. The field-matching is ASCII 4102 range case-insensitive but otherwise exact. Subsetting does 4103 not exclude the [RFC-5322] delimiting blank line between the 4104 header and the body; the blank line is included in all header 4105 fetches, except in the case of a message which has no body and 4106 no blank line. 4108 The MIME part specifier refers to the [MIME-IMB] header for 4109 this part. 4111 The TEXT part specifier refers to the text body of the message, 4112 omitting the [RFC-5322] header. 4114 Here is an example of a complex message with some of its 4115 part specifiers: 4117 HEADER ([RFC-5322] header of the message) 4118 TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4119 1 TEXT/PLAIN 4120 2 APPLICATION/OCTET-STREAM 4121 3 MESSAGE/RFC822 4122 3.HEADER ([RFC-5322] header of the message) 4123 3.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4124 3.1 TEXT/PLAIN 4125 3.2 APPLICATION/OCTET-STREAM 4126 4 MULTIPART/MIXED 4127 4.1 IMAGE/GIF 4128 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF) 4129 4.2 MESSAGE/RFC822 4130 4.2.HEADER ([RFC-5322] header of the message) 4131 4.2.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4132 4.2.1 TEXT/PLAIN 4133 4.2.2 MULTIPART/ALTERNATIVE 4134 4.2.2.1 TEXT/PLAIN 4135 4.2.2.2 TEXT/RICHTEXT 4137 It is possible to fetch a substring of the designated text. 4138 This is done by appending an open angle bracket ("<"), the 4139 octet position of the first desired octet, a period, the 4140 maximum number of octets desired, and a close angle bracket 4141 (">") to the part specifier. If the starting octet is beyond 4142 the end of the text, an empty string is returned. 4144 Any partial fetch that attempts to read beyond the end of the 4145 text is truncated as appropriate. A partial fetch that starts 4146 at octet 0 is returned as a partial fetch, even if this 4147 truncation happened. 4149 Note: This means that BODY[]<0.2048> of a 1500-octet message 4150 will return BODY[]<0> with a literal of size 1500, not 4151 BODY[]. 4153 Note: A substring fetch of a HEADER.FIELDS or 4154 HEADER.FIELDS.NOT part specifier is calculated after 4155 subsetting the header. 4157 The \Seen flag is implicitly set; if this causes the flags to 4158 change, they SHOULD be included as part of the FETCH responses. 4160 BODY.PEEK[
]<> An alternate form of BODY[
] 4161 that does not implicitly set the \Seen flag. 4163 BODYSTRUCTURE The [MIME-IMB] body structure of the message. This is 4164 computed by the server by parsing the [MIME-IMB] header fields in 4165 the [RFC-5322] header and [MIME-IMB] headers. 4167 ENVELOPE The envelope structure of the message. This is computed by 4168 the server by parsing the [RFC-5322] header into the component 4169 parts, defaulting various fields as necessary. 4171 FLAGS The flags that are set for this message. 4173 INTERNALDATE The internal date of the message. 4175 RFC822.SIZE The [RFC-5322] size of the message. 4177 UID The unique identifier for the message. 4179 Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)]) 4180 S: * 2 FETCH .... 4181 S: * 3 FETCH .... 4182 S: * 4 FETCH .... 4183 S: A654 OK FETCH completed 4185 6.4.6. STORE Command 4187 Arguments: sequence set 4188 message data item name 4189 value for message data item 4191 Responses: untagged responses: FETCH 4192 Result: OK - store completed 4193 NO - store error: can't store that data 4194 BAD - command unknown or arguments invalid 4196 The STORE command alters data associated with a message in the 4197 mailbox. Normally, STORE will return the updated value of the data 4198 with an untagged FETCH response. A suffix of ".SILENT" in the data 4199 item name prevents the untagged FETCH, and the server SHOULD assume 4200 that the client has determined the updated value itself or does not 4201 care about the updated value. 4203 Note: Regardless of whether or not the ".SILENT" suffix was used, 4204 the server SHOULD send an untagged FETCH response if a change to a 4205 message's flags from an external source is observed. The intent 4206 is that the status of the flags is determinate without a race 4207 condition. 4209 The currently defined data items that can be stored are: 4211 FLAGS Replace the flags for the message with the 4212 argument. The new value of the flags is returned as if a FETCH of 4213 those flags was done. 4215 FLAGS.SILENT Equivalent to FLAGS, but without returning 4216 a new value. 4218 +FLAGS Add the argument to the flags for the message. 4219 The new value of the flags is returned as if a FETCH of those 4220 flags was done. 4222 +FLAGS.SILENT Equivalent to +FLAGS, but without 4223 returning a new value. 4225 -FLAGS Remove the argument from the flags for the 4226 message. The new value of the flags is returned as if a FETCH of 4227 those flags was done. 4229 -FLAGS.SILENT Equivalent to -FLAGS, but without 4230 returning a new value. 4232 Example: C: A003 STORE 2:4 +FLAGS (\Deleted) 4233 S: * 2 FETCH (FLAGS (\Deleted \Seen)) 4234 S: * 3 FETCH (FLAGS (\Deleted)) 4235 S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen)) 4236 S: A003 OK STORE completed 4238 6.4.7. COPY Command 4240 Arguments: sequence set 4241 mailbox name 4243 Responses: no specific responses for this command 4245 Result: OK - copy completed 4246 NO - copy error: can't copy those messages or to that 4247 name 4248 BAD - command unknown or arguments invalid 4250 The COPY command copies the specified message(s) to the end of the 4251 specified destination mailbox. The flags and internal date of the 4252 message(s) SHOULD be preserved in the copy. 4254 If the destination mailbox does not exist, a server SHOULD return an 4255 error. It SHOULD NOT automatically create the mailbox. Unless it is 4256 certain that the destination mailbox can not be created, the server 4257 MUST send the response code "[TRYCREATE]" as the prefix of the text 4258 of the tagged NO response. This gives a hint to the client that it 4259 can attempt a CREATE command and retry the COPY if the CREATE is 4260 successful. 4262 If the COPY command is unsuccessful for any reason, server 4263 implementations MUST restore the destination mailbox to its state 4264 before the COPY attempt. 4266 On successful completion of a COPY, the server SHOULD return a 4267 COPYUID response code. 4269 In the case of a mailbox that has permissions set so that the client 4270 can COPY to the mailbox, but not SELECT or EXAMINE it, the server 4271 SHOULD NOT send an COPYUID response code as it would disclose 4272 information about the mailbox. 4274 In the case of a mailbox that has UIDNOTSTICKY status (see the 4275 UIDNOTSTICKY response code), the server MAY omit the COPYUID response 4276 code as it is not meaningful. 4278 If the server does not return the COPYUID response code, the client 4279 can discover this information by selecting the destination mailbox. 4280 The location of messages placed in the destination mailbox by COPY 4281 can be determined by using FETCH and/or SEARCH commands (e.g., for 4282 Message-ID). 4284 Example: C: A003 COPY 2:4 MEETING 4285 S: A003 OK COPY completed 4287 6.4.8. MOVE Command 4289 Arguments: sequence set 4290 mailbox name 4292 Responses: no specific responses for this command 4294 Result: OK - move completed 4295 NO - move error: can't move those messages or to that 4296 name 4297 BAD - command unknown or arguments invalid 4299 The MOVE command moves the specified message(s) to the end of the 4300 specified destination mailbox. The flags and internal date of the 4301 message(s) SHOULD be preserved. 4303 This means that a new message is created in the target mailbox with a 4304 new UID, the original message is removed from the source mailbox, and 4305 it appears to the client as a single action. This has the same 4306 effect for each message as this sequence: 4308 1. [UID] COPY 4310 2. [UID] STORE +FLAGS.SILENT \DELETED 4312 3. UID EXPUNGE 4314 Although the effect of the MOVE is the same as the preceding steps, 4315 the semantics are not identical: The intermediate states produced by 4316 those steps do not occur, and the response codes are different. In 4317 particular, though the COPY and EXPUNGE response codes will be 4318 returned, response codes for a STORE MUST NOT be generated and the 4319 \Deleted flag MUST NOT be set for any message. 4321 Because a MOVE applies to a set of messages, it might fail partway 4322 through the set. Regardless of whether the command is successful in 4323 moving the entire set, each individual message SHOULD either be moved 4324 or unaffected. The server MUST leave each message in a state where 4325 it is in at least one of the source or target mailboxes (no message 4326 can be lost or orphaned). The server SHOULD NOT leave any message in 4327 both mailboxes (it would be bad for a partial failure to result in a 4328 bunch of duplicate messages). This is true even if the server 4329 returns a tagged NO response to the command. 4331 Because of the similarity of MOVE to COPY, extensions that affect 4332 COPY affect MOVE in the same way. Response codes such as TRYCREATE 4333 (see Section 7.1), as well as those defined by extensions, are sent 4334 as appropriate. 4336 Servers SHOULD send COPYUID in response to a UID MOVE (see 4337 Section 6.4.9) command. For additional information see Section 7.1. 4339 Servers are also advised to send the COPYUID response code in an 4340 untagged OK before sending EXPUNGE or moved responses. (Sending 4341 COPYUID in the tagged OK, as described in the UIDPLUS specification, 4342 means that clients first receive an EXPUNGE for a message and 4343 afterwards COPYUID for the same message. It can be unnecessarily 4344 difficult to process that sequence usefully.) 4346 An example: 4347 C: a UID MOVE 42:69 foo 4348 S: * OK [COPYUID 432432 42:69 1202:1229] 4349 S: * 22 EXPUNGE 4350 S: (more expunges) 4351 S: a OK Done 4353 Note that the server may send unrelated EXPUNGE responses as well, if 4354 any happen to have been expunged at the same time; this is normal 4355 IMAP operation. 4357 Note that moving a message to the currently selected mailbox (that 4358 is, where the source and target mailboxes are the same) is allowed 4359 when copying the message to the currently selected mailbox is 4360 allowed. 4362 The server may send EXPUNGE responses before the tagged response, so 4363 the client cannot safely send more commands with message sequence 4364 number arguments while the server is processing MOVE. 4366 MOVE and UID MOVE can be pipelined with other commands, but care has 4367 to be taken. Both commands modify sequence numbers and also allow 4368 unrelated EXPUNGE responses. The renumbering of other messages in 4369 the source mailbox following any EXPUNGE response can be surprising 4370 and makes it unsafe to pipeline any command that relies on message 4371 sequence numbers after a MOVE or UID MOVE. Similarly, MOVE cannot be 4372 pipelined with a command that might cause message renumbering. See 4373 Section 5.5, for more information about ambiguities as well as 4374 handling requirements for both clients and servers. 4376 6.4.9. UID Command 4378 Arguments: command name 4379 command arguments 4381 Responses: untagged responses: FETCH, ESEARCH, EXPUNGE 4383 Result: OK - UID command completed 4384 NO - UID command error 4385 BAD - command unknown or arguments invalid 4387 The UID command has three forms. In the first form, it takes as its 4388 arguments a COPY, MOVE, FETCH, or STORE command with arguments 4389 appropriate for the associated command. However, the numbers in the 4390 sequence set argument are unique identifiers instead of message 4391 sequence numbers. Sequence set ranges are permitted, but there is no 4392 guarantee that unique identifiers will be contiguous. 4394 A non-existent unique identifier is ignored without any error message 4395 generated. Thus, it is possible for a UID FETCH command to return an 4396 OK without any data or a UID COPY, UID MOVE or UID STORE to return an 4397 OK without performing any operations. 4399 In the second form, the UID command takes an EXPUNGE command with an 4400 extra parameter the specified a sequence set of UIDs to operate on. 4401 The UID EXPUNGE command permanently removes all messages that both 4402 have the \Deleted flag set and have a UID that is included in the 4403 specified sequence set from the currently selected mailbox. If a 4404 message either does not have the \Deleted flag set or has a UID that 4405 is not included in the specified sequence set, it is not affected. 4407 UID EXPUNGE is particularly useful for disconnected use clients. 4408 By using UID EXPUNGE instead of EXPUNGE when resynchronizing with 4409 the server, the client can ensure that it does not inadvertantly 4410 remove any messages that have been marked as \Deleted by other 4411 clients between the time that the client was last connected and 4412 the time the client resynchronizes. 4414 Example: C: A003 UID EXPUNGE 3000:3002 4415 S: * 3 EXPUNGE 4416 S: * 3 EXPUNGE 4417 S: * 3 EXPUNGE 4418 S: A003 OK UID EXPUNGE completed 4420 In the third form, the UID command takes a SEARCH command with SEARCH 4421 command arguments. The interpretation of the arguments is the same 4422 as with SEARCH; however, the numbers returned in a ESEARCH response 4423 for a UID SEARCH command are unique identifiers instead of message 4424 sequence numbers. Also, the corresponding ESEARCH response MUST 4425 include the UID indicator. For example, the command UID SEARCH 1:100 4426 UID 443:557 returns the unique identifiers corresponding to the 4427 intersection of two sequence sets, the message sequence number range 4428 1:100 and the UID range 443:557. 4430 Note: in the above example, the UID range 443:557 appears. The 4431 same comment about a non-existent unique identifier being ignored 4432 without any error message also applies here. Hence, even if 4433 neither UID 443 or 557 exist, this range is valid and would 4434 include an existing UID 495. 4436 Also note that a UID range of 559:* always includes the UID of the 4437 last message in the mailbox, even if 559 is higher than any 4438 assigned UID value. This is because the contents of a range are 4439 independent of the order of the range endpoints. Thus, any UID 4440 range with * as one of the endpoints indicates at least one 4441 message (the message with the highest numbered UID), unless the 4442 mailbox is empty. 4444 The number after the "*" in an untagged FETCH or EXPUNGE response is 4445 always a message sequence number, not a unique identifier, even for a 4446 UID command response. However, server implementations MUST 4447 implicitly include the UID message data item as part of any FETCH 4448 response caused by a UID command, regardless of whether a UID was 4449 specified as a message data item to the FETCH. 4451 Note: The rule about including the UID message data item as part of a 4452 FETCH response primarily applies to the UID FETCH and UID STORE 4453 commands, including a UID FETCH command that does not include UID as 4454 a message data item. Although it is unlikely that the other UID 4455 commands will cause an untagged FETCH, this rule applies to these 4456 commands as well. 4458 Example: C: A999 UID FETCH 4827313:4828442 FLAGS 4459 S: * 23 FETCH (FLAGS (\Seen) UID 4827313) 4460 S: * 24 FETCH (FLAGS (\Seen) UID 4827943) 4461 S: * 25 FETCH (FLAGS (\Seen) UID 4828442) 4462 S: A999 OK UID FETCH completed 4464 6.5. Client Commands - Experimental/Expansion 4466 6.5.1. X Command 4468 Arguments: implementation defined 4470 Responses: implementation defined 4472 Result: OK - command completed 4473 NO - failure 4474 BAD - command unknown or arguments invalid 4476 Any command prefixed with an X is an experimental command. Commands 4477 which are not part of this specification, a standard or standards- 4478 track revision of this specification, or an IESG-approved 4479 experimental protocol, MUST use the X prefix. 4481 Any added untagged responses issued by an experimental command MUST 4482 also be prefixed with an X. Server implementations MUST NOT send any 4483 such untagged responses, unless the client requested it by issuing 4484 the associated experimental command. 4486 Example: C: a441 CAPABILITY 4487 S: * CAPABILITY IMAP4rev2 XPIG-LATIN 4488 S: a441 OK CAPABILITY completed 4489 C: A442 XPIG-LATIN 4490 S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay 4491 S: A442 OK XPIG-LATIN ompleted-cay 4493 7. Server Responses 4495 Server responses are in three forms: status responses, server data, 4496 and command continuation request. The information contained in a 4497 server response, identified by "Contents:" in the response 4498 descriptions below, is described by function, not by syntax. The 4499 precise syntax of server responses is described in the Formal Syntax 4500 section. 4502 The client MUST be prepared to accept any response at all times. 4504 Status responses can be tagged or untagged. Tagged status responses 4505 indicate the completion result (OK, NO, or BAD status) of a client 4506 command, and have a tag matching the command. 4508 Some status responses, and all server data, are untagged. An 4509 untagged response is indicated by the token "*" instead of a tag. 4510 Untagged status responses indicate server greeting, or server status 4511 that does not indicate the completion of a command (for example, an 4512 impending system shutdown alert). For historical reasons, untagged 4513 server data responses are also called "unsolicited data", although 4514 strictly speaking, only unilateral server data is truly 4515 "unsolicited". 4517 Certain server data MUST be recorded by the client when it is 4518 received; this is noted in the description of that data. Such data 4519 conveys critical information which affects the interpretation of all 4520 subsequent commands and responses (e.g., updates reflecting the 4521 creation or destruction of messages). 4523 Other server data SHOULD be recorded for later reference; if the 4524 client does not need to record the data, or if recording the data has 4525 no obvious purpose (e.g., a SEARCH response when no SEARCH command is 4526 in progress), the data SHOULD be ignored. 4528 An example of unilateral untagged server data occurs when the IMAP 4529 connection is in the selected state. In the selected state, the 4530 server checks the mailbox for new messages as part of command 4531 execution. Normally, this is part of the execution of every command; 4532 hence, a NOOP command suffices to check for new messages. If new 4533 messages are found, the server sends untagged EXISTS response 4534 reflecting the new size of the mailbox. Server implementations that 4535 offer multiple simultaneous access to the same mailbox SHOULD also 4536 send appropriate unilateral untagged FETCH and EXPUNGE responses if 4537 another agent changes the state of any message flags or expunges any 4538 messages. 4540 Command continuation request responses use the token "+" instead of a 4541 tag. These responses are sent by the server to indicate acceptance 4542 of an incomplete client command and readiness for the remainder of 4543 the command. 4545 7.1. Server Responses - Status Responses 4547 Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD 4548 can be tagged or untagged. PREAUTH and BYE are always untagged. 4550 Status responses MAY include an OPTIONAL "response code". A response 4551 code consists of data inside square brackets in the form of an atom, 4552 possibly followed by a space and arguments. The response code 4553 contains additional information or status codes for client software 4554 beyond the OK/NO/BAD condition, and are defined when there is a 4555 specific action that a client can take based upon the additional 4556 information. 4558 The currently defined response codes are: 4560 ALERT 4562 The human-readable text contains a special alert that MUST be 4563 presented to the user in a fashion that calls the user's 4564 attention to the message. 4566 ALREADYEXISTS 4568 The operation attempts to create something that already exists, 4569 such as when the CREATE or RENAME directories attempt to create 4570 a mailbox and there is already one of that name. 4572 C: o356 RENAME this that 4573 S: o356 NO [ALREADYEXISTS] Mailbox "that" already exists 4575 APPENDUID 4576 Followed by the UIDVALIDITY of the destination mailbox and the 4577 UID assigned to the appended message in the destination 4578 mailbox, indicates that the message has been appended to the 4579 destination mailbox with that UID. 4581 If the server also supports the [MULTIAPPEND] extension, and if 4582 multiple messages were appended in the APPEND command, then the 4583 second value is a UID set containing the UIDs assigned to the 4584 appended messages, in the order they were transmitted in the 4585 APPEND command. This UID set may not contain extraneous UIDs 4586 or the symbol "*". 4588 Note: the UID set form of the APPENDUID response code MUST 4589 NOT be used if only a single message was appended. In 4590 particular, a server MUST NOT send a range such as 123:123. 4591 This is because a client that does not support [MULTIAPPEND] 4592 expects only a single UID and not a UID set. 4594 UIDs are assigned in strictly ascending order in the mailbox 4595 (refer to Section 2.3.1.1); note that a range of 12:10 is 4596 exactly equivalent to 10:12 and refers to the sequence 4597 10,11,12. 4599 This response code is returned in a tagged OK response to the 4600 APPEND command. 4602 AUTHENTICATIONFAILED 4604 Authentication failed for some reason on which the server is 4605 unwilling to elaborate. Typically, this includes "unknown 4606 user" and "bad password". 4608 This is the same as not sending any response code, except that 4609 when a client sees AUTHENTICATIONFAILED, it knows that the 4610 problem wasn't, e.g., UNAVAILABLE, so there's no point in 4611 trying the same login/password again later. 4613 C: b LOGIN "fred" "foo" 4614 S: b NO [AUTHENTICATIONFAILED] Authentication failed 4616 AUTHORIZATIONFAILED 4618 Authentication succeeded in using the authentication identity, 4619 but the server cannot or will not allow the authentication 4620 identity to act as the requested authorization identity. This 4621 is only applicable when the authentication and authorization 4622 identities are different. 4624 C: c1 AUTHENTICATE PLAIN 4625 [...] 4626 S: c1 NO [AUTHORIZATIONFAILED] No such authorization-ID 4628 C: c2 AUTHENTICATE PLAIN 4629 [...] 4630 S: c2 NO [AUTHORIZATIONFAILED] Authenticator is not an admin 4632 BADCHARSET 4634 Optionally followed by a parenthesized list of charsets. A 4635 SEARCH failed because the given charset is not supported by 4636 this implementation. If the optional list of charsets is 4637 given, this lists the charsets that are supported by this 4638 implementation. 4640 CANNOT 4642 The operation violates some invariant of the server and can 4643 never succeed. 4645 C: l create "///////" 4646 S: l NO [CANNOT] Adjacent slashes are not supported 4648 CAPABILITY 4650 Followed by a list of capabilities. This can appear in the 4651 initial OK or PREAUTH response to transmit an initial 4652 capabilities list. It can also appear in tagged responses to 4653 LOGIN or AUTHENTICATE commands. This makes it unnecessary for 4654 a client to send a separate CAPABILITY command if it recognizes 4655 this response. 4657 CLIENTBUG 4659 The server has detected a client bug. This can accompany all 4660 of OK, NO, and BAD, depending on what the client bug is. 4662 C: k1 select "/archive/projects/experiment-iv" 4663 [...] 4664 S: k1 OK [READ-ONLY] Done 4665 C: k2 status "/archive/projects/experiment-iv" (messages) 4666 [...] 4667 S: k2 OK [CLIENTBUG] Done 4669 CLOSED 4671 The CLOSED response code has no parameters. A server return 4672 the CLOSED response code when the currently selected mailbox is 4673 closed implicitly using the SELECT/EXAMINE command on another 4674 mailbox. The CLOSED response code serves as a boundary between 4675 responses for the previously opened mailbox (which was closed) 4676 and the newly selected mailbox; all responses before the CLOSED 4677 response code relate to the mailbox that was closed, and all 4678 subsequent responses relate to the newly opened mailbox. 4680 There is no need to return the CLOSED response code on 4681 completion of the CLOSE or the UNSELECT command (or similar), 4682 whose purpose is to close the currently selected mailbox 4683 without opening a new one. 4685 CONTACTADMIN 4687 The user should contact the system administrator or support 4688 desk. 4690 C: e login "fred" "foo" 4691 S: e OK [CONTACTADMIN] 4693 COPYUID 4695 Followed by the UIDVALIDITY of the destination mailbox, a UID 4696 set containing the UIDs of the message(s) in the source mailbox 4697 that were copied to the destination mailbox and containing the 4698 UIDs assigned to the copied message(s) in the destination 4699 mailbox, indicates that the message(s) have been copied to the 4700 destination mailbox with the stated UID(s). 4702 The source UID set is in the order the message(s) were copied; 4703 the destination UID set corresponds to the source UID set and 4704 is in the same order. Neither of the UID sets may contain 4705 extraneous UIDs or the symbol "*". 4707 UIDs are assigned in strictly ascending order in the mailbox 4708 (refer to Section 2.3.1.1); note that a range of 12:10 is 4709 exactly equivalent to 10:12 and refers to the sequence 4710 10,11,12. 4712 This response code is returned in a tagged OK response to the 4713 COPY command. 4715 CORRUPTION 4716 The server discovered that some relevant data (e.g., the 4717 mailbox) are corrupt. This response code does not include any 4718 information about what's corrupt, but the server can write that 4719 to its logfiles. 4721 C: i select "/archive/projects/experiment-iv" 4722 S: i NO [CORRUPTION] Cannot open mailbox 4724 EXPIRED 4726 Either authentication succeeded or the server no longer had the 4727 necessary data; either way, access is no longer permitted using 4728 that passphrase. The client or user should get a new 4729 passphrase. 4731 C: d login "fred" "foo" 4732 S: d NO [EXPIRED] That password isn't valid any more 4734 EXPUNGEISSUED 4736 Someone else has issued an EXPUNGE for the same mailbox. The 4737 client may want to issue NOOP soon. [IMAP-MULTIACCESS] 4738 discusses this subject in depth. 4740 C: h search from fred@example.com 4741 S: * ESEARCH (TAG "h") ALL 1:3,5,8,13,21,42 4742 S: h OK [EXPUNGEISSUED] Search completed 4744 HASCHILDREN 4746 The mailbox delete operation failed because the mailbox has one 4747 or more children and the server doesn't allow deletion of 4748 mailboxes with children. 4750 C: m356 DELETE Notes 4751 S: o356 NO [HASCHILDREN] Mailbox "Notes" has children that need 4752 to be deleted first 4754 INUSE 4756 An operation has not been carried out because it involves 4757 sawing off a branch someone else is sitting on. Someone else 4758 may be holding an exclusive lock needed for this operation, or 4759 the operation may involve deleting a resource someone else is 4760 using, typically a mailbox. 4762 The operation may succeed if the client tries again later. 4764 C: g delete "/archive/projects/experiment-iv" 4765 S: g NO [INUSE] Mailbox in use 4767 LIMIT 4769 The operation ran up against an implementation limit of some 4770 kind, such as the number of flags on a single message or the 4771 number of flags used in a mailbox. 4773 C: m STORE 42 FLAGS f1 f2 f3 f4 f5 ... f250 4774 S: m NO [LIMIT] At most 32 flags in one mailbox supported 4776 NONEXISTENT 4778 The operation attempts to delete something that does not exist. 4779 Similar to ALREADYEXISTS. 4781 C: p RENAME this that 4782 S: p NO [NONEXISTENT] No such mailbox 4784 NOPERM 4786 The access control system (e.g., Access Control List (ACL), see 4787 [RFC4314] does not permit this user to carry out an operation, 4788 such as selecting or creating a mailbox. 4790 C: f select "/archive/projects/experiment-iv" 4791 S: f NO [NOPERM] Access denied 4793 OVERQUOTA 4795 The user would be over quota after the operation. (The user 4796 may or may not be over quota already.) 4798 Note that if the server sends OVERQUOTA but doesn't support the 4799 IMAP QUOTA extension defined by [RFC2087], then there is a 4800 quota, but the client cannot find out what the quota is. 4802 C: n1 uid copy 1:* oldmail 4803 S: n1 NO [OVERQUOTA] Sorry 4805 C: n2 uid copy 1:* oldmail 4806 S: n2 OK [OVERQUOTA] You are now over your soft quota 4808 PARSE 4809 The human-readable text represents an error in parsing the 4810 [RFC-5322] header or [MIME-IMB] headers of a message in the 4811 mailbox. 4813 PERMANENTFLAGS 4815 Followed by a parenthesized list of flags, indicates which of 4816 the known flags the client can change permanently. Any flags 4817 that are in the FLAGS untagged response, but not the 4818 PERMANENTFLAGS list, can not be set permanently. The 4819 PERMANENTFLAGS list can also include the special flag \*, which 4820 indicates that it is possible to create new keywords by 4821 attempting to store those keywords in the mailbox. If the 4822 client attempts to STORE a flag that is not in the 4823 PERMANENTFLAGS list, the server will either ignore the change 4824 or store the state change for the remainder of the current 4825 session only. 4827 There is no need for a server that included the special flag \* 4828 to return a new PERMANENTFLAGS response code when a new keyword 4829 was successfully set on a message upon client request. However 4830 if the server has a limit on the number of different keywords 4831 that can be stored in a mailbox and that limit is reached, the 4832 server MUST send a new PERMANENTFLAGS response code without the 4833 special flag \*. 4835 PRIVACYREQUIRED 4837 The operation is not permitted due to a lack of privacy. If 4838 Transport Layer Security (TLS) is not in use, the client could 4839 try STARTTLS (see Section 6.2.1) and then repeat the operation. 4841 C: d login "fred" "foo" 4842 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4844 C: d select inbox 4845 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4847 READ-ONLY 4849 The mailbox is selected read-only, or its access while selected 4850 has changed from read-write to read-only. 4852 READ-WRITE 4854 The mailbox is selected read-write, or its access while 4855 selected has changed from read-only to read-write. 4857 SERVERBUG 4859 The server encountered a bug in itself or violated one of its 4860 own invariants. 4862 C: j select "/archive/projects/experiment-iv" 4863 S: j NO [SERVERBUG] This should not happen 4865 TRYCREATE 4867 An APPEND or COPY attempt is failing because the target mailbox 4868 does not exist (as opposed to some other reason). This is a 4869 hint to the client that the operation can succeed if the 4870 mailbox is first created by the CREATE command. 4872 UIDNEXT 4874 Followed by a decimal number, indicates the next unique 4875 identifier value. Refer to Section 2.3.1.1 for more 4876 information. 4878 UIDNOTSTICKY 4880 The selected mailbox is supported by a mail store that does not 4881 support persistent UIDs; that is, UIDVALIDITY will be different 4882 each time the mailbox is selected. Consequently, APPEND or 4883 COPY to this mailbox will not return an APPENDUID or COPYUID 4884 response code. 4886 This response code is returned in an untagged NO response to 4887 the SELECT command. 4889 Note: servers SHOULD NOT have any UIDNOTSTICKY mail stores. 4890 This facility exists to support legacy mail stores in which 4891 it is technically infeasible to support persistent UIDs. 4892 This should be avoided when designing new mail stores. 4894 UIDVALIDITY 4896 Followed by a decimal number, indicates the unique identifier 4897 validity value. Refer to Section 2.3.1.1 for more information. 4899 UNAVAILABLE 4901 Temporary failure because a subsystem is down. For example, an 4902 IMAP server that uses a Lightweight Directory Access Protocol 4903 (LDAP) or Radius server for authentication might use this 4904 response code when the LDAP/Radius server is down. 4906 C: a LOGIN "fred" "foo" 4907 S: a NO [UNAVAILABLE] User's backend down for maintenance 4909 UNKNOWN-CTE 4911 The server does not know how to decode the section's Content- 4912 Transfer-Encoding. 4914 Client implementations MUST ignore response codes that they do not 4915 recognize. 4917 7.1.1. OK Response 4919 Contents: OPTIONAL response code 4920 human-readable text 4922 The OK response indicates an information message from the server. 4923 When tagged, it indicates successful completion of the associated 4924 command. The human-readable text MAY be presented to the user as an 4925 information message. The untagged form indicates an information-only 4926 message; the nature of the information MAY be indicated by a response 4927 code. 4929 The untagged form is also used as one of three possible greetings at 4930 connection startup. It indicates that the connection is not yet 4931 authenticated and that a LOGIN or an AUTHENTICATE command is needed. 4933 Example: S: * OK IMAP4rev2 server ready 4934 C: A001 LOGIN fred blurdybloop 4935 S: * OK [ALERT] System shutdown in 10 minutes 4936 S: A001 OK LOGIN Completed 4938 7.1.2. NO Response 4940 Contents: OPTIONAL response code 4941 human-readable text 4943 The NO response indicates an operational error message from the 4944 server. When tagged, it indicates unsuccessful completion of the 4945 associated command. The untagged form indicates a warning; the 4946 command can still complete successfully. The human-readable text 4947 describes the condition. 4949 Example: C: A222 COPY 1:2 owatagusiam 4950 S: * NO Disk is 98% full, please delete unnecessary data 4951 S: A222 OK COPY completed 4952 C: A223 COPY 3:200 blurdybloop 4953 S: * NO Disk is 98% full, please delete unnecessary data 4954 S: * NO Disk is 99% full, please delete unnecessary data 4955 S: A223 NO COPY failed: disk is full 4957 7.1.3. BAD Response 4959 Contents: OPTIONAL response code 4960 human-readable text 4962 The BAD response indicates an error message from the server. When 4963 tagged, it reports a protocol-level error in the client's command; 4964 the tag indicates the command that caused the error. The untagged 4965 form indicates a protocol-level error for which the associated 4966 command can not be determined; it can also indicate an internal 4967 server failure. The human-readable text describes the condition. 4969 Example: C: ...very long command line... 4970 S: * BAD Command line too long 4971 C: ...empty line... 4972 S: * BAD Empty command line 4973 C: A443 EXPUNGE 4974 S: * BAD Disk crash, attempting salvage to a new disk! 4975 S: * OK Salvage successful, no data lost 4976 S: A443 OK Expunge completed 4978 7.1.4. PREAUTH Response 4980 Contents: OPTIONAL response code 4981 human-readable text 4983 The PREAUTH response is always untagged, and is one of three possible 4984 greetings at connection startup. It indicates that the connection 4985 has already been authenticated by external means; thus no LOGIN/ 4986 AUTHENTICATE command is needed. 4988 Example: S: * PREAUTH IMAP4rev2 server logged in as Smith 4990 7.1.5. BYE Response 4992 Contents: OPTIONAL response code 4993 human-readable text 4995 The BYE response is always untagged, and indicates that the server is 4996 about to close the connection. The human-readable text MAY be 4997 displayed to the user in a status report by the client. The BYE 4998 response is sent under one of four conditions: 5000 1. as part of a normal logout sequence. The server will close the 5001 connection after sending the tagged OK response to the LOGOUT 5002 command. 5004 2. as a panic shutdown announcement. The server closes the 5005 connection immediately. 5007 3. as an announcement of an inactivity autologout. The server 5008 closes the connection immediately. 5010 4. as one of three possible greetings at connection startup, 5011 indicating that the server is not willing to accept a connection 5012 from this client. The server closes the connection immediately. 5014 The difference between a BYE that occurs as part of a normal LOGOUT 5015 sequence (the first case) and a BYE that occurs because of a failure 5016 (the other three cases) is that the connection closes immediately in 5017 the failure case. In all cases the client SHOULD continue to read 5018 response data from the server until the connection is closed; this 5019 will ensure that any pending untagged or completion responses are 5020 read and processed. 5022 Example: S: * BYE Autologout; idle for too long 5024 7.2. Server Responses - Server and Mailbox Status 5026 These responses are always untagged. This is how server and mailbox 5027 status data are transmitted from the server to the client. Many of 5028 these responses typically result from a command with the same name. 5030 7.2.1. The ENABLED Response 5032 Contents: capability listing 5034 The ENABLED response occurs as a result of an ENABLE command. The 5035 capability listing contains a space-separated listing of capability 5036 names that the server supports and that were successfully enabled. 5037 The ENABLED response may contain no capabilities, which means that no 5038 extensions listed by the client were successfully enabled. 5040 7.2.2. CAPABILITY Response 5042 Contents: capability listing 5043 The CAPABILITY response occurs as a result of a CAPABILITY command. 5044 The capability listing contains a space-separated listing of 5045 capability names that the server supports. The capability listing 5046 MUST include the atom "IMAP4rev2". 5048 In addition, client and server implementations MUST implement the 5049 STARTTLS, LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) 5050 capabilities. See the Security Considerations section for important 5051 information. 5053 A capability name which begins with "AUTH=" indicates that the server 5054 supports that particular authentication mechanism. 5056 The LOGINDISABLED capability indicates that the LOGIN command is 5057 disabled, and that the server will respond with a tagged NO response 5058 to any attempt to use the LOGIN command even if the user name and 5059 password are valid. An IMAP client MUST NOT issue the LOGIN command 5060 if the server advertises the LOGINDISABLED capability. 5062 Other capability names indicate that the server supports an 5063 extension, revision, or amendment to the IMAP4rev2 protocol. Server 5064 responses MUST conform to this document until the client issues a 5065 command that uses the associated capability. 5067 Capability names MUST either begin with "X" or be informational, 5068 experimental or standards-track IMAP4rev2 extensions, revisions, or 5069 amendments registered with IANA. A server SHOULD NOT offer 5070 unregistered or non-standard capability names, unless such names are 5071 prefixed with an "X". 5073 Client implementations SHOULD NOT require any capability name other 5074 than "IMAP4rev2", and MUST ignore any unknown capability names. 5076 A server MAY send capabilities automatically, by using the CAPABILITY 5077 response code in the initial PREAUTH or OK responses, and by sending 5078 an updated CAPABILITY response code in the tagged OK response as part 5079 of a successful authentication. It is unnecessary for a client to 5080 send a separate CAPABILITY command if it recognizes these automatic 5081 capabilities. 5083 Example: S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI XPIG-LATIN 5085 7.2.3. LIST Response 5087 Contents: name attributes 5088 hierarchy delimiter 5089 name 5090 OPTIONAL extension data 5092 The LIST response occurs as a result of a LIST command. It returns a 5093 single name that matches the LIST specification. There can be 5094 multiple LIST responses for a single LIST command. 5096 The following base mailbox name attributes are defined: 5098 \NonExistent The "\NonExistent" attribute indicates that a mailbox 5099 name does not refer to an existing mailbox. Note that this 5100 attribute is not meaningful by itself, as mailbox names that match 5101 the canonical LIST pattern but don't exist must not be returned 5102 unless one of the two conditions listed below is also satisfied: 5104 1. The mailbox name also satisfies the selection criteria (for 5105 example, it is subscribed and the "SUBSCRIBED" selection 5106 option has been specified). 5108 2. "RECURSIVEMATCH" has been specified, and the mailbox name has 5109 at least one descendant mailbox name that does not match the 5110 LIST pattern and does match the selection criteria. 5112 In practice, this means that the "\NonExistent" attribute is 5113 usually returned with one or more of "\Subscribed", "\Remote", 5114 "\HasChildren", or the CHILDINFO extended data item. 5116 The "\NonExistent" attribute implies "\NoSelect". 5118 \Noinferiors It is not possible for any child levels of hierarchy to 5119 exist under this name; no child levels exist now and none can be 5120 created in the future. 5122 \Noselect It is not possible to use this name as a selectable 5123 mailbox. 5125 \HasChildren The presence of this attribute indicates that the 5126 mailbox has child mailboxes. A server SHOULD NOT set this 5127 attribute if there are child mailboxes and the user does not have 5128 permission to access any of them. In this case, \HasNoChildren 5129 SHOULD be used. In many cases, however, a server may not be able 5130 to efficiently compute whether a user has access to any child 5131 mailbox. Note that even though the \HasChildren attribute for a 5132 mailbox must be correct at the time of processing of the mailbox, 5133 a client must be prepared to deal with a situation when a mailbox 5134 is marked with the \HasChildren attribute, but no child mailbox 5135 appears in the response to the LIST command. This might happen, 5136 for example, due to children mailboxes being deleted or made 5137 inaccessible to the user (using access control) by another client 5138 before the server is able to list them. 5140 \HasNoChildren The presence of this attribute indicates that the 5141 mailbox has NO child mailboxes that are accessible to the 5142 currently authenticated user. 5144 \Marked The mailbox has been marked "interesting" by the server; the 5145 mailbox probably contains messages that have been added since the 5146 last time the mailbox was selected. 5148 \Unmarked The mailbox does not contain any additional messages since 5149 the last time the mailbox was selected. 5151 \Subscribed The mailbox name was subscribed to using the SUBSCRIBE 5152 command. 5154 \Remote The mailbox is a remote mailbox. 5156 It is an error for the server to return both a \HasChildren and a 5157 \HasNoChildren attribute in the same LIST response. 5159 Note: the \HasNoChildren attribute should not be confused with the 5160 \NoInferiors attribute, which indicates that no child mailboxes 5161 exist now and none can be created in the future. 5163 If it is not feasible for the server to determine whether or not the 5164 mailbox is "interesting", the server SHOULD NOT send either \Marked 5165 or \Unmarked. The server MUST NOT send more than one of \Marked, 5166 \Unmarked, and \Noselect for a single mailbox, and MAY send none of 5167 these. 5169 In addition to the base mailbox name attributes defined above, an 5170 IMAP server MAY also include any or all of the following attributes 5171 that denote "role" (or "special-use") of a mailbox. These attributes 5172 are included along with base attributes defined above. A given 5173 mailbox may have none, one, or more than one of these attributes. In 5174 some cases, a special use is advice to a client about what to put in 5175 that mailbox. In other cases, it's advice to a client about what to 5176 expect to find there. 5178 \All This mailbox presents all messages in the user's message store. 5179 Implementations MAY omit some messages, such as, perhaps, those in 5180 \Trash and \Junk. When this special use is supported, it is 5181 almost certain to represent a virtual mailbox. 5183 \Archive This mailbox is used to archive messages. The meaning of 5184 an "archival" mailbox is server-dependent; typically, it will be 5185 used to get messages out of the inbox, or otherwise keep them out 5186 of the user's way, while still making them accessible. 5188 \Drafts This mailbox is used to hold draft messages -- typically, 5189 messages that are being composed but have not yet been sent. In 5190 some server implementations, this might be a virtual mailbox, 5191 containing messages from other mailboxes that are marked with the 5192 "\Draft" message flag. Alternatively, this might just be advice 5193 that a client put drafts here. 5195 \Flagged This mailbox presents all messages marked in some way as 5196 "important". When this special use is supported, it is likely to 5197 represent a virtual mailbox collecting messages (from other 5198 mailboxes) that are marked with the "\Flagged" message flag. 5200 \Junk This mailbox is where messages deemed to be junk mail are 5201 held. Some server implementations might put messages here 5202 automatically. Alternatively, this might just be advice to a 5203 client-side spam filter. 5205 \Sent This mailbox is used to hold copies of messages that have been 5206 sent. Some server implementations might put messages here 5207 automatically. Alternatively, this might just be advice that a 5208 client save sent messages here. 5210 \Trash This mailbox is used to hold messages that have been deleted 5211 or marked for deletion. In some server implementations, this 5212 might be a virtual mailbox, containing messages from other 5213 mailboxes that are marked with the "\Deleted" message flag. 5214 Alternatively, this might just be advice that a client that 5215 chooses not to use the IMAP "\Deleted" model should use this as 5216 its trash location. In server implementations that strictly 5217 expect the IMAP "\Deleted" model, this special use is likely not 5218 to be supported. 5220 All of special-use attributes are OPTIONAL, and any given server or 5221 message store may support any combination of the attributes, or none 5222 at all. In most cases, there will likely be at most one mailbox with 5223 a given attribute for a given user, but in some server or message 5224 store implementations it might be possible for multiple mailboxes to 5225 have the same special-use attribute. 5227 Special-use attributes are likely to be user-specific. User Adam 5228 might share his \Sent mailbox with user Barb, but that mailbox is 5229 unlikely to also serve as Barb's \Sent mailbox. 5231 Other mailbox name attributes can be found in the "IMAP Mailbox Name 5232 Attributes" registry [IMAP-MAILBOX-NAME-ATTRS-REG]. 5234 The hierarchy delimiter is a character used to delimit levels of 5235 hierarchy in a mailbox name. A client can use it to create child 5236 mailboxes, and to search higher or lower levels of naming hierarchy. 5237 All children of a top-level hierarchy node MUST use the same 5238 separator character. A NIL hierarchy delimiter means that no 5239 hierarchy exists; the name is a "flat" name. 5241 The name represents an unambiguous left-to-right hierarchy, and MUST 5242 be valid for use as a reference in LIST command. Unless \Noselect or 5243 \NonExistent is indicated, the name MUST also be valid as an argument 5244 for commands, such as SELECT, that accept mailbox names. 5246 The name might be followed by an OPTIONAL series of extended fields, 5247 a parenthesized list of tagged data (also referred to as "extended 5248 data item"). The first element of an extended field is a string, 5249 which identifies the type of data. [RFC5258] specified requirements 5250 on string registration (which are called "tags" there; such tags are 5251 not to be confused with IMAP command tags), in particular it said 5252 that "Tags MUST be registered with IANA". This document doesn't 5253 change that. See Section 9.5 of [RFC5258] for the registration 5254 template. The server MAY return data in the extended fields that was 5255 not directly solicited by the client in the corresponding LIST 5256 command. For example, the client can enable extra extended fields by 5257 using another IMAP extension that make use of the extended LIST 5258 responses. The client MUST ignore all extended fields it doesn't 5259 recognize. 5261 Example: S: * LIST (\Noselect) "/" ~/Mail/foo 5263 Example: S: * LIST (\Marked) ":" Tables (tablecloth (("edge" "lacy") 5264 ("color" "red")) Sample "text") 5265 S: * LIST () ":" Tables:new (tablecloth ("edge" "lacy") 5266 Sample ("text" "more text")) 5268 7.2.4. NAMESPACE Response 5270 Contents: the prefix and hierarchy delimiter to the server's 5271 Personal Namespace(s), Other Users' Namespace(s), and 5272 Shared Namespace(s) 5274 The NAMESPACE response occurs as a result of a NAMESPACE command. It 5275 contains the prefix and hierarchy delimiter to the server's Personal 5276 Namespace(s), Other Users' Namespace(s), and Shared Namespace(s) that 5277 the server wishes to expose. The response will contain a NIL for any 5278 namespace class that is not available. Namespace-Response-Extensions 5279 ABNF non terminal is defined for extensibility and MAY be included in 5280 the response. 5282 Example: S: * NAMESPACE (("" "/")) (("~" "/")) NIL 5284 7.2.5. STATUS Response 5286 Contents: name 5287 status parenthesized list 5289 The STATUS response occurs as a result of an STATUS command. It 5290 returns the mailbox name that matches the STATUS specification and 5291 the requested mailbox status information. 5293 Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 5295 7.2.6. ESEARCH Response 5297 Contents: one or more search-return-data pairs 5299 The ESEARCH response occurs as a result of a SEARCH or UID SEARCH 5300 command. 5302 The ESEARCH response starts with an optional search correlator. If 5303 it is missing, then the response was not caused by a particular IMAP 5304 command, whereas if it is present, it contains the tag of the command 5305 that caused the response to be returned. 5307 The search correlator is followed by an optional UID indicator. If 5308 this indicator is present, all data in the ESEARCH response refers to 5309 UIDs, otherwise all returned data refers to message numbers. 5311 The rest of the ESEARCH response contains one or more search data 5312 pairs. Each pair starts with unique return item name, followed by a 5313 space and the corresponding data. Search data pairs may be returned 5314 in any order. Unless specified otherwise by an extension, any return 5315 item name SHOULD appear only once in an ESEARCH response. 5317 [[TBD: describe the most common search data pairs returned.]] 5319 Example: S: * ESEARCH UID COUNT 5 ALL 4:19,21,28 5321 Example: S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28 5323 Example: S: * ESEARCH COUNT 5 ALL 1:17,21 5325 7.2.7. FLAGS Response 5327 Contents: flag parenthesized list 5329 The FLAGS response occurs as a result of a SELECT or EXAMINE command. 5330 The flag parenthesized list identifies the flags (at a minimum, the 5331 system-defined flags) that are applicable for this mailbox. Flags 5332 other than the system flags can also exist, depending on server 5333 implementation. 5335 The update from the FLAGS response MUST be recorded by the client. 5337 Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5339 7.3. Server Responses - Mailbox Size 5341 These responses are always untagged. This is how changes in the size 5342 of the mailbox are transmitted from the server to the client. 5343 Immediately following the "*" token is a number that represents a 5344 message count. 5346 7.3.1. EXISTS Response 5348 Contents: none 5350 The EXISTS response reports the number of messages in the mailbox. 5351 This response occurs as a result of a SELECT or EXAMINE command, and 5352 if the size of the mailbox changes (e.g., new messages). 5354 The update from the EXISTS response MUST be recorded by the client. 5356 Example: S: * 23 EXISTS 5358 7.4. Server Responses - Message Status 5360 These responses are always untagged. This is how message data are 5361 transmitted from the server to the client, often as a result of a 5362 command with the same name. Immediately following the "*" token is a 5363 number that represents a message sequence number. 5365 7.4.1. EXPUNGE Response 5367 Contents: none 5369 The EXPUNGE response reports that the specified message sequence 5370 number has been permanently removed from the mailbox. The message 5371 sequence number for each successive message in the mailbox is 5372 immediately decremented by 1, and this decrement is reflected in 5373 message sequence numbers in subsequent responses (including other 5374 untagged EXPUNGE responses). 5376 The EXPUNGE response also decrements the number of messages in the 5377 mailbox; it is not necessary to send an EXISTS response with the new 5378 value. 5380 As a result of the immediate decrement rule, message sequence numbers 5381 that appear in a set of successive EXPUNGE responses depend upon 5382 whether the messages are removed starting from lower numbers to 5383 higher numbers, or from higher numbers to lower numbers. For 5384 example, if the last 5 messages in a 9-message mailbox are expunged, 5385 a "lower to higher" server will send five untagged EXPUNGE responses 5386 for message sequence number 5, whereas a "higher to lower server" 5387 will send successive untagged EXPUNGE responses for message sequence 5388 numbers 9, 8, 7, 6, and 5. 5390 An EXPUNGE response MUST NOT be sent when no command is in progress, 5391 nor while responding to a FETCH, STORE, or SEARCH command. This rule 5392 is necessary to prevent a loss of synchronization of message sequence 5393 numbers between client and server. A command is not "in progress" 5394 until the complete command has been received; in particular, a 5395 command is not "in progress" during the negotiation of command 5396 continuation. 5398 Note: UID FETCH, UID STORE, and UID SEARCH are different commands 5399 from FETCH, STORE, and SEARCH. An EXPUNGE response MAY be sent 5400 during a UID command. 5402 The update from the EXPUNGE response MUST be recorded by the client. 5404 Example: S: * 44 EXPUNGE 5406 7.4.2. FETCH Response 5408 Contents: message data 5410 The FETCH response returns data about a message to the client. The 5411 data are pairs of data item names and their values in parentheses. 5412 This response occurs as the result of a FETCH or STORE command, as 5413 well as by unilateral server decision (e.g., flag updates). 5415 The current data items are: 5417 BINARY[]<> 5419 An or expressing the content of the 5420 specified section after removing any Content-Transfer-Encoding- 5421 related encoding. If is present it refers to the 5422 offset within the DECODED section data. 5424 If the domain of the decoded data is "8bit" and the data does 5425 not contain the NUL octet, the server SHOULD return the data in 5426 a instead of a ; this allows the client to 5427 determine if the "8bit" data contains the NUL octet without 5428 having to explicitly scan the data stream for for NULs. 5430 Messaging clients and servers have been notoriously lax in 5431 their adherence to the Internet CRLF convention for terminating 5432 lines of textual data (text/* media types) in Internet 5433 protocols. When sending data in BINARY[...] FETCH data item, 5434 servers MUST ensure that textual line-oriented sections are 5435 always transmitted using the IMAP4 CRLF line termination 5436 syntax, regardless of the underlying storage representation of 5437 the data on the server. 5439 If the server does not know how to decode the section's 5440 Content-Transfer-Encoding, it MUST fail the request and issue a 5441 "NO" response that contains the "UNKNOWN-CTE" response code. 5443 BINARY.SIZE[] 5445 The size of the section after removing any Content-Transfer- 5446 Encoding-related encoding. The value returned MUST match the 5447 size of the or that will be returned by 5448 the corresponding FETCH BINARY request. 5450 If the server does not know how to decode the section's 5451 Content-Transfer-Encoding, it MUST fail the request and issue a 5452 "NO" response that contains the "UNKNOWN-CTE" response code. 5454 BODY A form of BODYSTRUCTURE without extension data. 5456 BODY[
]<> 5458 A string expressing the body contents of the specified section. 5459 The string SHOULD be interpreted by the client according to the 5460 content transfer encoding, body type, and subtype. 5462 If the origin octet is specified, this string is a substring of 5463 the entire body contents, starting at that origin octet. This 5464 means that BODY[]<0> MAY be truncated, but BODY[] is NEVER 5465 truncated. 5467 Note: The origin octet facility MUST NOT be used by a server 5468 in a FETCH response unless the client specifically requested 5469 it by means of a FETCH of a BODY[
]<> data 5470 item. 5472 8-bit textual data is permitted if a [CHARSET] identifier is 5473 part of the body parameter parenthesized list for this section. 5474 Note that headers (part specifiers HEADER or MIME, or the 5475 header portion of a MESSAGE/RFC822 or MESSAGE/GLOBAL part), MAY 5476 be in UTF-8. Note also that the [RFC-5322] delimiting blank 5477 line between the header and the body is not affected by header 5478 line subsetting; the blank line is always included as part of 5479 header data, except in the case of a message which has no body 5480 and no blank line. 5482 Non-textual data such as binary data MUST be transfer encoded 5483 into a textual form, such as BASE64, prior to being sent to the 5484 client. To derive the original binary data, the client MUST 5485 decode the transfer encoded string. 5487 BODYSTRUCTURE 5489 A parenthesized list that describes the [MIME-IMB] body 5490 structure of a message. This is computed by the server by 5491 parsing the [MIME-IMB] header fields, defaulting various fields 5492 as necessary. 5494 For example, a simple text message of 48 lines and 2279 octets 5495 can have a body structure of: ("TEXT" "PLAIN" ("CHARSET" "US- 5496 ASCII") NIL NIL "7BIT" 2279 48) 5498 Multiple parts are indicated by parenthesis nesting. Instead 5499 of a body type as the first element of the parenthesized list, 5500 there is a sequence of one or more nested body structures. The 5501 second element of the parenthesized list is the multipart 5502 subtype (mixed, digest, parallel, alternative, etc.). 5504 For example, a two part message consisting of a text and a 5505 BASE64-encoded text attachment can have a body structure of: 5506 (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 5507 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") 5508 "<960723163407.20117h@cac.washington.edu>" "Compiler diff" 5509 "BASE64" 4554 73) "MIXED") 5511 Extension data follows the multipart subtype. Extension data 5512 is never returned with the BODY fetch, but can be returned with 5513 a BODYSTRUCTURE fetch. Extension data, if present, MUST be in 5514 the defined order. The extension data of a multipart body part 5515 are in the following order: 5517 body parameter parenthesized list A parenthesized list of 5518 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5519 "bar" is the value of "foo", and "rag" is the value of 5520 "baz"] as defined in [MIME-IMB]. Servers SHOULD decode 5521 parameter value continuations and parameter value character 5522 sets as described in [RFC2231], for example, if the message 5523 contains parameters "baz*0", "baz*1" and "baz*2", the server 5524 should RFC2231-decode them, concatenate and return the 5525 resulting value as a parameter "baz". Similarly, if the 5526 message contains parameters "foo*0*" and "foo*1*", the 5527 server should RFC2231-decode them, convert to UTF-8, 5528 concatenate and return the resulting value as a parameter 5529 "foo*". 5531 body disposition A parenthesized list, consisting of a 5532 disposition type string, followed by a parenthesized list of 5533 disposition attribute/value pairs as defined in 5534 [DISPOSITION]. Servers SHOULD decode parameter value 5535 continuations as described in [RFC2231]. 5537 body language A string or parenthesized list giving the body 5538 language value as defined in [LANGUAGE-TAGS]. 5540 body location A string giving the body content URI as defined 5541 in [LOCATION]. 5543 Any following extension data are not yet defined in this 5544 version of the protocol. Such extension data can consist of 5545 zero or more NILs, strings, numbers, or potentially nested 5546 parenthesized lists of such data. Client implementations that 5547 do a BODYSTRUCTURE fetch MUST be prepared to accept such 5548 extension data. Server implementations MUST NOT send such 5549 extension data until it has been defined by a revision of this 5550 protocol. 5552 The basic fields of a non-multipart body part are in the 5553 following order: 5555 body type A string giving the content media type name as 5556 defined in [MIME-IMB]. 5558 body subtype A string giving the content subtype name as 5559 defined in [MIME-IMB]. 5561 body parameter parenthesized list A parenthesized list of 5562 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5563 "bar" is the value of "foo" and "rag" is the value of "baz"] 5564 as defined in [MIME-IMB]. 5566 body id A string giving the Content-ID header field value as 5567 defined in Section 7 of [MIME-IMB]. 5569 body description A string giving the Content-Description 5570 header field value as defined in Section 8 of [MIME-IMB]. 5572 body encoding A string giving the content transfer encoding as 5573 defined in Section 6 of [MIME-IMB]. 5575 body size A number giving the size of the body in octets. 5576 Note that this size is the size in its transfer encoding and 5577 not the resulting size after any decoding. 5579 A body type of type MESSAGE and subtype RFC822 contains, 5580 immediately after the basic fields, the envelope structure, 5581 body structure, and size in text lines of the encapsulated 5582 message. 5584 A body type of type TEXT contains, immediately after the basic 5585 fields, the size of the body in text lines. Note that this 5586 size is the size in its content transfer encoding and not the 5587 resulting size after any decoding. 5589 Extension data follows the basic fields and the type-specific 5590 fields listed above. Extension data is never returned with the 5591 BODY fetch, but can be returned with a BODYSTRUCTURE fetch. 5592 Extension data, if present, MUST be in the defined order. 5594 The extension data of a non-multipart body part are in the 5595 following order: 5597 body MD5 A string giving the body MD5 value as defined in 5598 [MD5]. 5600 body disposition A parenthesized list with the same content 5601 and function as the body disposition for a multipart body 5602 part. 5604 body language A string or parenthesized list giving the body 5605 language value as defined in [LANGUAGE-TAGS]. 5607 body location A string giving the body content URI as defined 5608 in [LOCATION]. 5610 Any following extension data are not yet defined in this 5611 version of the protocol, and would be as described above under 5612 multipart extension data. 5614 ENVELOPE 5616 A parenthesized list that describes the envelope structure of a 5617 message. This is computed by the server by parsing the 5618 [RFC-5322] header into the component parts, defaulting various 5619 fields as necessary. 5621 The fields of the envelope structure are in the following 5622 order: date, subject, from, sender, reply-to, to, cc, bcc, in- 5623 reply-to, and message-id. The date, subject, in-reply-to, and 5624 message-id fields are strings. The from, sender, reply-to, to, 5625 cc, and bcc fields are parenthesized lists of address 5626 structures. 5628 An address structure is a parenthesized list that describes an 5629 electronic mail address. The fields of an address structure 5630 are in the following order: personal name, [SMTP] at-domain- 5631 list (source route, obs-route), mailbox name, and host name. 5633 [RFC-5322] group syntax is indicated by a special form of 5634 address structure in which the host name field is NIL. If the 5635 mailbox name field is also NIL, this is an end of group marker 5636 (semi-colon in RFC 822 syntax). If the mailbox name field is 5637 non-NIL, this is a start of group marker, and the mailbox name 5638 field holds the group name phrase. 5640 If the Date, Subject, In-Reply-To, and Message-ID header lines 5641 are absent in the [RFC-5322] header, the corresponding member 5642 of the envelope is NIL; if these header lines are present but 5643 empty the corresponding member of the envelope is the empty 5644 string. 5646 Note: some servers may return a NIL envelope member in the 5647 "present but empty" case. Clients SHOULD treat NIL and 5648 empty string as identical. 5650 Note: [RFC-5322] requires that all messages have a valid 5651 Date header. Therefore, the date member in the envelope can 5652 not be NIL or the empty string. 5654 Note: [RFC-5322] requires that the In-Reply-To and Message- 5655 ID headers, if present, have non-empty content. Therefore, 5656 the in-reply-to and message-id members in the envelope can 5657 not be the empty string. 5659 If the From, To, Cc, and Bcc header lines are absent in the 5660 [RFC-5322] header, or are present but empty, the corresponding 5661 member of the envelope is NIL. 5663 If the Sender or Reply-To lines are absent in the [RFC-5322] 5664 header, or are present but empty, the server sets the 5665 corresponding member of the envelope to be the same value as 5666 the from member (the client is not expected to know to do 5667 this). 5669 Note: [RFC-5322] requires that all messages have a valid 5670 From header. Therefore, the from, sender, and reply-to 5671 members in the envelope can not be NIL. 5673 FLAGS A parenthesized list of flags that are set for this message. 5675 INTERNALDATE A string representing the internal date of the message. 5677 RFC822.SIZE A number expressing the [RFC-5322] size of the message. 5679 UID A number expressing the unique identifier of the message. 5681 If the server chooses to send unsolicited FETCH responses, they MUST 5682 include UID FETCH item. Note that this is a new requirement when 5683 compared to RFC 3501. 5685 Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827) 5687 7.5. Server Responses - Command Continuation Request 5689 The command continuation request response is indicated by a "+" token 5690 instead of a tag. This form of response indicates that the server is 5691 ready to accept the continuation of a command from the client. The 5692 remainder of this response is a line of text. 5694 This response is used in the AUTHENTICATE command to transmit server 5695 data to the client, and request additional client data. This 5696 response is also used if an argument to any command is a 5697 synchronizing literal. 5699 The client is not permitted to send the octets of the synchronizing 5700 literal unless the server indicates that it is expected. This 5701 permits the server to process commands and reject errors on a line- 5702 by-line basis. The remainder of the command, including the CRLF that 5703 terminates a command, follows the octets of the literal. If there 5704 are any additional command arguments, the literal octets are followed 5705 by a space and those arguments. 5707 Example: C: A001 LOGIN {11} 5708 S: + Ready for additional command text 5709 C: FRED FOOBAR {7} 5710 S: + Ready for additional command text 5711 C: fat man 5712 S: A001 OK LOGIN completed 5713 C: A044 BLURDYBLOOP {102856} 5714 S: A044 BAD No such command as "BLURDYBLOOP" 5716 8. Sample IMAP4rev2 connection 5718 The following is a transcript of an IMAP4rev2 connection. A long 5719 line in this sample is broken for editorial clarity. 5721 S: * OK IMAP4rev2 Service Ready 5722 C: a001 login mrc secret 5723 S: a001 OK LOGIN completed 5724 C: a002 select inbox 5725 S: * 18 EXISTS 5726 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5727 S: * OK [UIDVALIDITY 3857529045] UIDs valid 5728 S: a002 OK [READ-WRITE] SELECT completed 5729 C: a003 fetch 12 full 5730 S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700" 5731 RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)" 5732 "IMAP4rev2 WG mtg summary and minutes" 5733 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5734 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5735 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5736 ((NIL NIL "imap" "cac.washington.edu")) 5737 ((NIL NIL "minutes" "CNRI.Reston.VA.US") 5738 ("John Klensin" NIL "KLENSIN" "MIT.EDU")) NIL NIL 5739 "") 5740 BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 5741 92)) 5742 S: a003 OK FETCH completed 5743 C: a004 fetch 12 body[header] 5744 S: * 12 FETCH (BODY[HEADER] {342} 5745 S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT) 5746 S: From: Terry Gray 5747 S: Subject: IMAP4rev2 WG mtg summary and minutes 5748 S: To: imap@cac.washington.edu 5749 S: cc: minutes@CNRI.Reston.VA.US, John Klensin 5750 S: Message-Id: 5751 S: MIME-Version: 1.0 5752 S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 5753 S: 5754 S: ) 5755 S: a004 OK FETCH completed 5756 C: a005 store 12 +flags \deleted 5757 S: * 12 FETCH (FLAGS (\Seen \Deleted)) 5758 S: a005 OK +FLAGS completed 5759 C: a006 logout 5760 S: * BYE IMAP4rev2 server terminating connection 5761 S: a006 OK LOGOUT completed 5762 9. Formal Syntax 5764 The following syntax specification uses the Augmented Backus-Naur 5765 Form (ABNF) notation as specified in [ABNF]. 5767 In the case of alternative or optional rules in which a later rule 5768 overlaps an earlier rule, the rule which is listed earlier MUST take 5769 priority. For example, "\Seen" when parsed as a flag is the \Seen 5770 flag name and not a flag-extension, even though "\Seen" can be parsed 5771 as a flag-extension. Some, but not all, instances of this rule are 5772 noted below. 5774 Note: [ABNF] rules MUST be followed strictly; in particular: 5776 (1) Except as noted otherwise, all alphabetic characters are case- 5777 insensitive. The use of upper or lower case characters to define 5778 token strings is for editorial clarity only. Implementations MUST 5779 accept these strings in a case-insensitive fashion. 5781 (2) In all cases, SP refers to exactly one space. It is NOT 5782 permitted to substitute TAB, insert additional spaces, or 5783 otherwise treat SP as being equivalent to LWSP. 5785 (3) The ASCII NUL character, %x00, MUST NOT be used at any time. 5787 address = "(" addr-name SP addr-adl SP addr-mailbox SP 5788 addr-host ")" 5790 addr-adl = nstring 5791 ; Holds route from [RFC-5322] obs-route if 5792 ; non-NIL 5794 addr-host = nstring 5795 ; NIL indicates [RFC-5322] group syntax. 5796 ; Otherwise, holds [RFC-5322] domain name 5798 addr-mailbox = nstring 5799 ; NIL indicates end of [RFC-5322] group; if 5800 ; non-NIL and addr-host is NIL, holds 5801 ; [RFC-5322] group name. 5802 ; Otherwise, holds [RFC-5322] local-part 5803 ; after removing [RFC-5322] quoting 5805 addr-name = nstring 5806 ; If non-NIL, holds phrase from [RFC-5322] 5807 ; mailbox after removing [RFC-5322] quoting 5809 append = "APPEND" SP mailbox [SP flag-list] [SP date-time] SP 5810 literal 5812 append-uid = uniqueid 5814 astring = 1*ASTRING-CHAR / string 5816 ASTRING-CHAR = ATOM-CHAR / resp-specials 5818 atom = 1*ATOM-CHAR 5820 ATOM-CHAR = 5822 atom-specials = "(" / ")" / "{" / SP / CTL / list-wildcards / 5823 quoted-specials / resp-specials 5825 authenticate = "AUTHENTICATE" SP auth-type [SP initial-resp] 5826 *(CRLF base64) 5828 auth-type = atom 5829 ; Defined by [SASL] 5831 base64 = *(4base64-char) [base64-terminal] 5833 base64-char = ALPHA / DIGIT / "+" / "/" 5834 ; Case-sensitive 5836 base64-terminal = (2base64-char "==") / (3base64-char "=") 5838 body = "(" (body-type-1part / body-type-mpart) ")" 5840 body-extension = nstring / number / 5841 "(" body-extension *(SP body-extension) ")" 5842 ; Future expansion. Client implementations 5843 ; MUST accept body-extension fields. Server 5844 ; implementations MUST NOT generate 5845 ; body-extension fields except as defined by 5846 ; future standard or standards-track 5847 ; revisions of this specification. 5849 body-ext-1part = body-fld-md5 [SP body-fld-dsp [SP body-fld-lang 5850 [SP body-fld-loc *(SP body-extension)]]] 5851 ; MUST NOT be returned on non-extensible 5852 ; "BODY" fetch 5854 body-ext-mpart = body-fld-param [SP body-fld-dsp [SP body-fld-lang 5855 [SP body-fld-loc *(SP body-extension)]]] 5856 ; MUST NOT be returned on non-extensible 5857 ; "BODY" fetch 5859 body-fields = body-fld-param SP body-fld-id SP body-fld-desc SP 5860 body-fld-enc SP body-fld-octets 5862 body-fld-desc = nstring 5864 body-fld-dsp = "(" string SP body-fld-param ")" / nil 5866 body-fld-enc = (DQUOTE ("7BIT" / "8BIT" / "BINARY" / "BASE64"/ 5867 "QUOTED-PRINTABLE") DQUOTE) / string 5868 ; Content-Transfer-Encoding header field value. 5869 ; Defaults to "7BIT" (as per RFC 2045) 5870 ; if not present in the body part. 5872 body-fld-id = nstring 5874 body-fld-lang = nstring / "(" string *(SP string) ")" 5876 body-fld-loc = nstring 5878 body-fld-lines = number 5880 body-fld-md5 = nstring 5882 body-fld-octets = number 5884 body-fld-param = "(" string SP string *(SP string SP string) ")" / nil 5886 body-type-1part = (body-type-basic / body-type-msg / body-type-text) 5887 [SP body-ext-1part] 5889 body-type-basic = media-basic SP body-fields 5890 ; MESSAGE subtype MUST NOT be "RFC822" or "GLOBAL" 5892 body-type-mpart = 1*body SP media-subtype 5893 [SP body-ext-mpart] 5894 ; MULTIPART body part 5896 body-type-msg = media-message SP body-fields SP envelope 5897 SP body SP body-fld-lines 5899 body-type-text = media-text SP body-fields SP body-fld-lines 5901 capability = ("AUTH=" auth-type) / atom 5902 ; New capabilities MUST begin with "X" or be 5903 ; registered with IANA in 5904 ; a standards-track, an experimental 5905 ; or an informational RFC. 5907 capability-data = "CAPABILITY" *(SP capability) SP "IMAP4rev2" 5908 *(SP capability) 5909 ; Servers MUST implement the STARTTLS, AUTH=PLAIN, 5910 ; and LOGINDISABLED capabilities. 5911 ; Servers which offer RFC 1730 compatibility MUST 5912 ; list "IMAP4" as the first capability. 5913 ; Servers which offer RFC 3501 compatibility MUST 5914 ; list "IMAP4rev1" as one of capabilities. 5916 CHAR = 5918 CHAR8 = %x01-ff 5919 ; any OCTET except NUL, %x00 5921 charset = atom / quoted 5923 childinfo-extended-item = "CHILDINFO" SP "(" 5924 list-select-base-opt-quoted 5925 *(SP list-select-base-opt-quoted) ")" 5926 ; Extended data item (mbox-list-extended-item) 5927 ; returned when the RECURSIVEMATCH 5928 ; selection option is specified. 5929 ; Note 1: the CHILDINFO extended data item tag can be 5930 ; returned with and without surrounding quotes, as per 5931 ; mbox-list-extended-item-tag production. 5932 ; Note 2: The selection options are always returned 5933 ; quoted, unlike their specification in 5934 ; the extended LIST command. 5936 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 5937 ; attributes for CHILDREN return option, at most one 5938 ; possible per LIST response 5940 command = tag SP (command-any / command-auth / command-nonauth / 5941 command-select) CRLF 5942 ; Modal based on state 5944 command-any = "CAPABILITY" / "LOGOUT" / "NOOP" / enable / x-command 5945 ; Valid in all states 5947 command-auth = append / create / delete / examine / list / 5948 Namespace-Command / 5949 rename / select / status / subscribe / unsubscribe / 5950 idle 5951 ; Valid only in Authenticated or Selected state 5953 command-nonauth = login / authenticate / "STARTTLS" 5954 ; Valid only when in Not Authenticated state 5956 command-select = "CLOSE" / "UNSELECT" / "EXPUNGE" / copy / 5957 move / fetch / store / search / uid 5958 ; Valid only when in Selected state 5960 continue-req = "+" SP (resp-text / base64) CRLF 5962 copy = "COPY" SP sequence-set SP mailbox 5964 create = "CREATE" SP mailbox 5965 ; Use of INBOX gives a NO error 5967 date = date-text / DQUOTE date-text DQUOTE 5969 date-day = 1*2DIGIT 5970 ; Day of month 5972 date-day-fixed = (SP DIGIT) / 2DIGIT 5973 ; Fixed-format version of date-day 5975 date-month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / 5976 "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" 5978 date-text = date-day "-" date-month "-" date-year 5980 date-year = 4DIGIT 5982 date-time = DQUOTE date-day-fixed "-" date-month "-" date-year 5983 SP time SP zone DQUOTE 5985 delete = "DELETE" SP mailbox 5986 ; Use of INBOX gives a NO error 5988 digit-nz = %x31-39 5989 ; 1-9 5991 eitem-standard-tag = atom 5992 ; a tag for LIST extended data item defined in a Standard 5993 ; Track or Experimental RFC. 5995 eitem-vendor-tag = vendor-token "-" atom 5996 ; a vendor-specific tag for LIST extended data item 5998 enable = "ENABLE" 1*(SP capability) 6000 enable-data = "ENABLED" *(SP capability) 6002 envelope = "(" env-date SP env-subject SP env-from SP 6003 env-sender SP env-reply-to SP env-to SP env-cc SP 6004 env-bcc SP env-in-reply-to SP env-message-id ")" 6006 env-bcc = "(" 1*address ")" / nil 6008 env-cc = "(" 1*address ")" / nil 6010 env-date = nstring 6012 env-from = "(" 1*address ")" / nil 6014 env-in-reply-to = nstring 6016 env-message-id = nstring 6018 env-reply-to = "(" 1*address ")" / nil 6020 env-sender = "(" 1*address ")" / nil 6022 env-subject = nstring 6024 env-to = "(" 1*address ")" / nil 6026 esearch-response = "ESEARCH" [search-correlator] [SP "UID"] 6027 *(SP search-return-data) 6028 ; ESEARCH response replaces SEARCH response 6029 ; from IMAP4rev1. 6031 examine = "EXAMINE" SP mailbox 6033 fetch = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" / 6034 fetch-att / "(" fetch-att *(SP fetch-att) ")") 6036 fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" / 6037 "RFC822.SIZE" / 6038 "BODY" ["STRUCTURE"] / "UID" / 6039 "BODY" section [partial] / 6040 "BODY.PEEK" section [partial] / 6041 "BINARY" [".PEEK"] section-binary [partial] / 6042 "BINARY.SIZE" section-binary 6044 flag = "\Answered" / "\Flagged" / "\Deleted" / 6045 "\Seen" / "\Draft" / flag-keyword / flag-extension 6046 ; Does not include "\Recent" 6048 flag-extension = "\" atom 6049 ; Future expansion. Client implementations 6050 ; MUST accept flag-extension flags. Server 6051 ; implementations MUST NOT generate 6052 ; flag-extension flags except as defined by 6053 ; future standard or standards-track 6054 ; revisions of this specification. 6055 ; "\Recent" was defined in RFC 3501 6056 ; and is now deprecated. 6058 flag-fetch = flag 6060 flag-keyword = "$MDNSent" / "$Forwarded" / "$Junk" / 6061 "$NotJunk" / "$Phishing" / atom 6063 flag-list = "(" [flag *(SP flag)] ")" 6065 flag-perm = flag / "\*" 6067 greeting = "*" SP (resp-cond-auth / resp-cond-bye) CRLF 6069 header-fld-name = astring 6071 header-list = "(" header-fld-name *(SP header-fld-name) ")" 6073 idle = "IDLE" CRLF "DONE" 6075 initial-resp = (base64 / "=") 6076 ; "initial response" defined in 6077 ; Section 5.1 of [RFC4422] 6079 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 6080 [SP list-return-opts] 6082 list-mailbox = 1*list-char / string 6084 list-char = ATOM-CHAR / list-wildcards / resp-specials 6086 list-return-opts = "RETURN" SP 6087 "(" [return-option *(SP return-option)] ")" 6088 ; list return options, e.g., CHILDREN 6090 list-select-base-opt = "SUBSCRIBED" / option-extension 6091 ; options that can be used by themselves 6093 list-select-base-opt-quoted = DQUOTE list-select-base-opt DQUOTE 6095 list-select-independent-opt = "REMOTE" / option-extension 6096 ; options that do not syntactically interact with 6097 ; other options 6099 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 6100 ; options that require a list-select-base-opt 6101 ; to also be present 6103 list-select-opt = list-select-base-opt / list-select-independent-opt 6104 / list-select-mod-opt 6105 ; An option registration template is described in 6106 ; Section 9.3 of this document. 6108 list-select-opts = "(" [ 6109 (*(list-select-opt SP) list-select-base-opt 6110 *(SP list-select-opt)) 6111 / (list-select-independent-opt 6112 *(SP list-select-independent-opt)) 6113 ] ")" 6114 ; Any number of options may be in any order. 6115 ; If a list-select-mod-opt appears, then a 6116 ; list-select-base-opt must also appear. 6117 ; This allows these: 6118 ; () 6119 ; (REMOTE) 6120 ; (SUBSCRIBED) 6121 ; (SUBSCRIBED REMOTE) 6122 ; (SUBSCRIBED RECURSIVEMATCH) 6123 ; (SUBSCRIBED REMOTE RECURSIVEMATCH) 6124 ; But does NOT allow these: 6125 ; (RECURSIVEMATCH) 6126 ; (REMOTE RECURSIVEMATCH) 6128 list-wildcards = "%" / "*" 6130 literal = "{" number ["+"] "}" CRLF *CHAR8 6131 ; represents the number of CHAR8s. 6132 ; A non-synchronizing literal is distinguished from 6133 ; a synchronizing literal by presence of the "+" 6134 ; before the closing "}". 6135 ; Non synchronizing literals are not allowed when 6136 ; sent from server to the client. 6138 literal8 = "~{" number "}" CRLF *OCTET 6139 ; represents the number of OCTETs 6140 ; in the response string. 6142 login = "LOGIN" SP userid SP password 6144 mailbox = "INBOX" / astring 6145 ; INBOX is case-insensitive. All case variants of 6146 ; INBOX (e.g., "iNbOx") MUST be interpreted as INBOX 6147 ; not as an astring. An astring which consists of 6148 ; the case-insensitive sequence "I" "N" "B" "O" "X" 6149 ; is considered to be INBOX and not an astring. 6150 ; Refer to section 5.1 for further 6151 ; semantic details of mailbox names. 6153 mailbox-data = "FLAGS" SP flag-list / "LIST" SP mailbox-list / 6154 esearch-response / 6155 "STATUS" SP mailbox SP "(" [status-att-list] ")" / 6156 number SP "EXISTS" / Namespace-Response 6158 mailbox-list = "(" [mbx-list-flags] ")" SP 6159 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 6160 [SP mbox-list-extended] 6161 ; This is the list information pointed to by the ABNF 6162 ; item "mailbox-data", which is defined in [IMAP4] 6164 mbox-list-extended = "(" [mbox-list-extended-item 6165 *(SP mbox-list-extended-item)] ")" 6167 mbox-list-extended-item = mbox-list-extended-item-tag SP 6168 tagged-ext-val 6170 mbox-list-extended-item-tag = astring 6171 ; The content MUST conform to either "eitem-vendor-tag" 6172 ; or "eitem-standard-tag" ABNF productions. 6174 mbox-or-pat = list-mailbox / patterns 6176 mbx-list-flags = *(mbx-list-oflag SP) mbx-list-sflag 6177 *(SP mbx-list-oflag) / 6178 mbx-list-oflag *(SP mbx-list-oflag) 6180 mbx-list-oflag = "\Noinferiors" / child-mbox-flag / 6181 "\Subscribed" / "\Remote" / flag-extension 6182 ; Other flags; multiple possible per LIST response 6184 mbx-list-sflag = "\NonExistent" / "\Noselect" / "\Marked" / "\Unmarked" 6185 ; Selectability flags; only one per LIST response 6187 media-basic = ((DQUOTE ("APPLICATION" / "AUDIO" / "IMAGE" / 6188 "FONT" / "MESSAGE" / "MODEL" / "VIDEO" ) DQUOTE) 6189 / string) 6190 SP media-subtype 6191 ; Defined in [MIME-IMT]. 6192 ; FONT defined in RFC 8081. 6194 media-message = DQUOTE "MESSAGE" DQUOTE SP 6195 DQUOTE ("RFC822" / "GLOBAL") DQUOTE 6196 ; Defined in [MIME-IMT] 6198 media-subtype = string 6199 ; Defined in [MIME-IMT] 6201 media-text = DQUOTE "TEXT" DQUOTE SP media-subtype 6202 ; Defined in [MIME-IMT] 6204 message-data = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att)) 6206 move = "MOVE" SP sequence-set SP mailbox 6208 msg-att = "(" (msg-att-dynamic / msg-att-static) 6209 *(SP (msg-att-dynamic / msg-att-static)) ")" 6211 msg-att-dynamic = "FLAGS" SP "(" [flag-fetch *(SP flag-fetch)] ")" 6212 ; MAY change for a message 6214 msg-att-static = "ENVELOPE" SP envelope / "INTERNALDATE" SP date-time / 6215 "RFC822.SIZE" SP number / 6216 "BODY" ["STRUCTURE"] SP body / 6217 "BODY" section ["<" number ">"] SP nstring / 6218 "BINARY" section-binary SP (nstring / literal8) / 6219 "BINARY.SIZE" section-binary SP number / 6220 "UID" SP uniqueid 6221 ; MUST NOT change for a message 6223 name-component = 1*UTF8-CHAR 6224 ; MUST NOT contain ".", "/", "%", or "*" 6226 Namespace = nil / "(" 1*Namespace-Descr ")" 6228 Namespace-Command = "NAMESPACE" 6230 Namespace-Descr = "(" string SP 6231 (DQUOTE QUOTED-CHAR DQUOTE / nil) 6232 [Namespace-Response-Extensions] ")" 6234 Namespace-Response-Extensions = *Namespace-Response-Extension 6236 Namespace-Response-Extension = SP string SP 6237 "(" string *(SP string) ")" 6239 Namespace-Response = "NAMESPACE" SP Namespace 6240 SP Namespace SP Namespace 6241 ; The first Namespace is the Personal Namespace(s). 6242 ; The second Namespace is the Other Users' 6243 ; Namespace(s). 6244 ; The third Namespace is the Shared Namespace(s). 6246 nil = "NIL" 6248 nstring = string / nil 6250 number = 1*DIGIT 6251 ; Unsigned 32-bit integer 6252 ; (0 <= n < 4,294,967,296) 6254 number64 = 1*DIGIT 6255 ; Unsigned 63-bit integer 6256 ; (0 <= n <= 9,223,372,036,854,775,807) 6258 nz-number = digit-nz *DIGIT 6259 ; Non-zero unsigned 32-bit integer 6260 ; (0 < n < 4,294,967,296) 6262 oldname-extended-item = "OLDNAME" SP "(" mailbox ")" 6263 ; Extended data item (mbox-list-extended-item) 6264 ; returned in a LIST response when a mailbox is 6265 ; renamed or deleted. Also returned when 6266 ; the server canonicalized the provided mailbox 6267 ; name. 6268 ; Note 1: the OLDNAME tag can be returned 6269 ; with or without surrounding quotes, as per 6270 ; mbox-list-extended-item-tag production. 6272 option-extension = (option-standard-tag / option-vendor-tag) 6273 [SP option-value] 6275 option-standard-tag = atom 6276 ; an option defined in a Standards Track or 6277 ; Experimental RFC 6279 option-val-comp = astring / 6280 option-val-comp *(SP option-val-comp) / 6281 "(" option-val-comp ")" 6283 option-value = "(" option-val-comp ")" 6285 option-vendor-tag = vendor-token "-" atom 6286 ; a vendor-specific option, non-standard 6288 partial-range = number ["." nz-number] 6289 ; Copied from RFC 5092 (IMAP URL) 6291 partial = "<" number "." nz-number ">" 6292 ; Partial FETCH request. 0-based offset of 6293 ; the first octet, followed by the number of octets 6294 ; in the fragment. 6296 password = astring 6298 patterns = "(" list-mailbox ")" 6299 ; [RFC5258] supports multiple patterns, 6300 ; but this document only requires one 6301 ; to be supported. 6302 ; If the server is also implementing 6303 ; [RFC5258], "patterns" syntax from that 6304 ; document must be followed. 6306 quoted = DQUOTE *QUOTED-CHAR DQUOTE 6308 QUOTED-CHAR = / 6309 "\" quoted-specials / UTF8-2 / UTF8-3 / UTF8-4 6311 quoted-specials = DQUOTE / "\" 6313 rename = "RENAME" SP mailbox SP mailbox 6314 ; Use of INBOX as a destination gives a NO error 6316 response = *(continue-req / response-data) response-done 6318 response-data = "*" SP (resp-cond-state / resp-cond-bye / 6319 mailbox-data / message-data / capability-data / 6320 enable-data) CRLF 6322 response-done = response-tagged / response-fatal 6324 response-fatal = "*" SP resp-cond-bye CRLF 6325 ; Server closes connection immediately 6327 response-tagged = tag SP resp-cond-state CRLF 6329 resp-code-apnd = "APPENDUID" SP nz-number SP append-uid 6331 resp-code-copy = "COPYUID" SP nz-number SP uid-set SP uid-set 6333 resp-cond-auth = ("OK" / "PREAUTH") SP resp-text 6334 ; Authentication condition 6336 resp-cond-bye = "BYE" SP resp-text 6338 resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text 6339 ; Status condition 6341 resp-specials = "]" 6343 resp-text = ["[" resp-text-code "]" SP] [text] 6345 resp-text-code = "ALERT" / 6346 "BADCHARSET" [SP "(" charset *(SP charset) ")" ] / 6347 capability-data / "PARSE" / 6348 "PERMANENTFLAGS" SP 6349 "(" [flag-perm *(SP flag-perm)] ")" / 6350 "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / 6351 "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number / 6352 resp-code-apnd / resp-code-copy / "UIDNOTSTICKY" / 6353 "UNAVAILABLE" / "AUTHENTICATIONFAILED" / 6354 "AUTHORIZATIONFAILED" / "EXPIRED" / 6355 "PRIVACYREQUIRED" / "CONTACTADMIN" / "NOPERM" / 6356 "INUSE" / "EXPUNGEISSUED" / "CORRUPTION" / 6357 "SERVERBUG" / "CLIENTBUG" / "CANNOT" / 6358 "LIMIT" / "OVERQUOTA" / "ALREADYEXISTS" / 6359 "NONEXISTENT" / "NOTSAVED" / "HASCHILDREN" / 6360 "CLOSED" / 6361 "UNKNOWN-CTE" / 6362 atom [SP 1*] 6364 return-option = "SUBSCRIBED" / "CHILDREN" / status-option / 6365 option-extension 6367 search = "SEARCH" [search-return-opts] 6368 SP search-program 6370 search-correlator = SP "(" "TAG" SP tag-string ")" 6372 search-key = "ALL" / "ANSWERED" / "BCC" SP astring / 6373 "BEFORE" SP date / "BODY" SP astring / 6374 "CC" SP astring / "DELETED" / "FLAGGED" / 6375 "FROM" SP astring / "KEYWORD" SP flag-keyword / 6376 "ON" SP date / "SEEN" / 6377 "SINCE" SP date / "SUBJECT" SP astring / 6378 "TEXT" SP astring / "TO" SP astring / 6379 "UNANSWERED" / "UNDELETED" / "UNFLAGGED" / 6380 "UNKEYWORD" SP flag-keyword / "UNSEEN" / 6381 ; Above this line were in [IMAP2] 6382 "DRAFT" / "HEADER" SP header-fld-name SP astring / 6383 "LARGER" SP number / "NOT" SP search-key / 6384 "OR" SP search-key SP search-key / 6385 "SENTBEFORE" SP date / "SENTON" SP date / 6386 "SENTSINCE" SP date / "SMALLER" SP number / 6387 "UID" SP sequence-set / "UNDRAFT" / sequence-set / 6388 "(" search-key *(SP search-key) ")" 6390 search-modifier-name = tagged-ext-label 6392 search-mod-params = tagged-ext-val 6393 ; This non-terminal shows recommended syntax 6394 ; for future extensions. 6396 search-program = ["CHARSET" SP charset SP] 6397 search-key *(SP search-key) 6398 ; CHARSET argument to SEARCH MUST be 6399 ; registered with IANA. 6401 search-ret-data-ext = search-modifier-name SP search-return-value 6402 ; Note that not every SEARCH return option 6403 ; is required to have the corresponding 6404 ; ESEARCH return data. 6406 search-return-data = "MIN" SP nz-number / 6407 "MAX" SP nz-number / 6408 "ALL" SP sequence-set / 6409 "COUNT" SP number / 6410 search-ret-data-ext 6411 ; All return data items conform to 6412 ; search-ret-data-ext syntax. 6413 ; Note that "$" marker is not allowed 6414 ; after the ALL return data item. 6416 search-return-opts = SP "RETURN" SP "(" [search-return-opt 6417 *(SP search-return-opt)] ")" 6419 search-return-opt = "MIN" / "MAX" / "ALL" / "COUNT" / 6420 "SAVE" / 6421 search-ret-opt-ext 6422 ; conforms to generic search-ret-opt-ext 6423 ; syntax 6425 search-ret-opt-ext = search-modifier-name [SP search-mod-params] 6427 search-return-value = tagged-ext-val 6428 ; Data for the returned search option. 6429 ; A single "nz-number"/"number"/"number64" value 6430 ; can be returned as an atom (i.e., without 6431 ; quoting). A sequence-set can be returned 6432 ; as an atom as well. 6434 section = "[" [section-spec] "]" 6435 section-binary = "[" [section-part] "]" 6437 section-msgtext = "HEADER" / "HEADER.FIELDS" [".NOT"] SP header-list / 6438 "TEXT" 6439 ; top-level or MESSAGE/RFC822 or MESSAGE/GLOBAL part 6441 section-part = nz-number *("." nz-number) 6442 ; body part reference. 6443 ; Allows for accessing nested body parts. 6445 section-spec = section-msgtext / (section-part ["." section-text]) 6447 section-text = section-msgtext / "MIME" 6448 ; text other than actual body part (headers, etc.) 6450 select = "SELECT" SP mailbox 6452 seq-number = nz-number / "*" 6453 ; message sequence number (COPY, FETCH, STORE 6454 ; commands) or unique identifier (UID COPY, 6455 ; UID FETCH, UID STORE commands). 6456 ; * represents the largest number in use. In 6457 ; the case of message sequence numbers, it is 6458 ; the number of messages in a non-empty mailbox. 6459 ; In the case of unique identifiers, it is the 6460 ; unique identifier of the last message in the 6461 ; mailbox or, if the mailbox is empty, the 6462 ; mailbox's current UIDNEXT value. 6463 ; The server should respond with a tagged BAD 6464 ; response to a command that uses a message 6465 ; sequence number greater than the number of 6466 ; messages in the selected mailbox. This 6467 ; includes "*" if the selected mailbox is empty. 6469 seq-range = seq-number ":" seq-number 6470 ; two seq-number values and all values between 6471 ; these two regardless of order. 6472 ; Example: 2:4 and 4:2 are equivalent and indicate 6473 ; values 2, 3, and 4. 6474 ; Example: a unique identifier sequence range of 6475 ; 3291:* includes the UID of the last message in 6476 ; the mailbox, even if that value is less than 3291. 6478 sequence-set = (seq-number / seq-range) ["," sequence-set] 6479 ; set of seq-number values, regardless of order. 6480 ; Servers MAY coalesce overlaps and/or execute the 6481 ; sequence in any order. 6482 ; Example: a message sequence number set of 6483 ; 2,4:7,9,12:* for a mailbox with 15 messages is 6484 ; equivalent to 2,4,5,6,7,9,12,13,14,15 6485 ; Example: a message sequence number set of *:4,5:7 6486 ; for a mailbox with 10 messages is equivalent to 6487 ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and 6488 ; overlap coalesced to be 4,5,6,7,8,9,10. 6490 sequence-set =/ seq-last-command 6491 ; Allow for "result of the last command" indicator. 6493 seq-last-command = "$" 6495 status = "STATUS" SP mailbox SP 6496 "(" status-att *(SP status-att) ")" 6498 status-att = "MESSAGES" / "UIDNEXT" / "UIDVALIDITY" / 6499 "UNSEEN" / "DELETED" / "SIZE" 6501 status-att-val = ("MESSAGES" SP number) / 6502 ("UIDNEXT" SP nz-number) / 6503 ("UIDVALIDITY" SP nz-number) / 6504 ("UNSEEN" SP number) / 6505 ("DELETED" SP number) / 6506 ("SIZE" SP number64) 6507 ; Extensions to the STATUS responses 6508 ; should extend this production. 6509 ; Extensions should use the generic 6510 ; syntax defined by tagged-ext. 6512 status-att-list = status-att-val *(SP status-att-val) 6514 status-option = "STATUS" SP "(" status-att *(SP status-att) ")" 6515 ; This ABNF production complies with 6516 ; syntax. 6518 store = "STORE" SP sequence-set SP store-att-flags 6520 store-att-flags = (["+" / "-"] "FLAGS" [".SILENT"]) SP 6521 (flag-list / (flag *(SP flag))) 6523 string = quoted / literal 6525 subscribe = "SUBSCRIBE" SP mailbox 6527 tag = 1* 6529 tag-string = astring 6530 ; represented as 6532 tagged-ext-label = tagged-label-fchar *tagged-label-char 6533 ; Is a valid RFC 3501 "atom". 6535 tagged-label-fchar = ALPHA / "-" / "_" / "." 6537 tagged-label-char = tagged-label-fchar / DIGIT / ":" 6539 tagged-ext-comp = astring / 6540 tagged-ext-comp *(SP tagged-ext-comp) / 6541 "(" tagged-ext-comp ")" 6542 ; Extensions that follow this general 6543 ; syntax should use nstring instead of 6544 ; astring when appropriate in the context 6545 ; of the extension. 6546 ; Note that a message set or a "number" 6547 ; can always be represented as an "atom". 6548 ; An URL should be represented as 6549 ; a "quoted" string. 6551 tagged-ext-simple = sequence-set / number / number64 6553 tagged-ext-val = tagged-ext-simple / 6554 "(" [tagged-ext-comp] ")" 6556 text = 1*(TEXT-CHAR / UTF8-2 / UTF8-3 / UTF8-4) 6557 ; Non ASCII text can only be returned 6558 ; after ENABLE IMAP4rev2 command 6560 TEXT-CHAR = 6562 time = 2DIGIT ":" 2DIGIT ":" 2DIGIT 6563 ; Hours minutes seconds 6565 uid = "UID" SP 6566 (copy / move / fetch / search / store / uid-expunge) 6567 ; Unique identifiers used instead of message 6568 ; sequence numbers 6570 uid-expunge = "EXPUNGE" SP sequence-set 6571 ; Unique identifiers used instead of message 6572 ; sequence numbers 6574 uid-set = (uniqueid / uid-range) *("," uid-set) 6576 uid-range = (uniqueid ":" uniqueid) 6577 ; two uniqueid values and all values 6578 ; between these two regards of order. 6579 ; Example: 2:4 and 4:2 are equivalent. 6581 uniqueid = nz-number 6582 ; Strictly ascending 6584 unsubscribe = "UNSUBSCRIBE" SP mailbox 6586 userid = astring 6588 UTF8-2 = 6590 UTF8-3 = 6592 UTF8-4 = 6594 vendor-token = "vendor." name-component 6595 ; Definition copied from RFC 2244. 6596 ; MUST be registered with IANA 6598 x-command = "X" atom 6600 zone = ("+" / "-") 4DIGIT 6601 ; Signed four-digit value of hhmm representing 6602 ; hours and minutes east of Greenwich (that is, 6603 ; the amount that the given time differs from 6604 ; Universal Time). Subtracting the timezone 6605 ; from the given time will give the UT form. 6606 ; The Universal Time zone is "+0000". 6608 10. Author's Note 6610 This document is a revision or rewrite of earlier documents, and 6611 supercedes the protocol specification in those documents: RFC 3501, 6612 RFC 2060, RFC 1730, unpublished IMAP2bis.TXT document, RFC 1176, and 6613 RFC 1064. 6615 11. Security Considerations 6617 IMAP4rev2 protocol transactions, including electronic mail data, are 6618 sent in the clear over the network unless protection from snooping is 6619 negotiated. This can be accomplished either by the use of IMAPS 6620 service, STARTTLS command, negotiated privacy protection in the 6621 AUTHENTICATE command, or some other protection mechanism. 6623 11.1. STARTTLS Security Considerations 6625 IMAP client and server implementations MUST comply with relevant TLS 6626 recommendations from [RFC8314]. Additionally, when using TLS 1.2, 6627 IMAP implementations MUST implement 6628 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite, and SHOULD 6629 implement the TLS_RSA_WITH_AES_128_CBC_SHA [TLS] cipher suite. This 6630 is important as it assures that any two compliant implementations can 6631 be configured to interoperate. Other TLS cipher suites recommended 6632 in RFC 7525 are RECOMMENDED: TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 6633 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 and 6634 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384. All other cipher suites are 6635 OPTIONAL. Note that this is a change from section 2.1 of [IMAP-TLS]. 6637 During the [TLS] negotiation, the client MUST check its understanding 6638 of the server hostname against the server's identity as presented in 6639 the server Certificate message, in order to prevent man-in-the-middle 6640 attacks. This procedure is described in [RFC7817]. 6642 Both the client and server MUST check the result of the STARTTLS 6643 command and subsequent [TLS] negotiation to see whether acceptable 6644 authentication and/or privacy was achieved. 6646 11.2. COPYUID and APPENDUID response codes 6648 The COPYUID and APPENDUID response codes return information about the 6649 mailbox, which may be considered sensitive if the mailbox has 6650 permissions set that permit the client to COPY or APPEND to the 6651 mailbox, but not SELECT or EXAMINE it. 6653 Consequently, these response codes SHOULD NOT be issued if the client 6654 does not have access to SELECT or EXAMINE the mailbox. 6656 11.3. LIST command and Other Users' namespace 6658 In response to a LIST command containing an argument of the Other 6659 Users' Namespace prefix, a server SHOULD NOT list users that have not 6660 granted list access to their personal mailboxes to the currently 6661 authenticated user. Providing such a list, could compromise security 6662 by potentially disclosing confidential information of who is located 6663 on the server, or providing a starting point of a list of user 6664 accounts to attack. 6666 11.4. Other Security Considerations 6668 A server error message for an AUTHENTICATE command which fails due to 6669 invalid credentials SHOULD NOT detail why the credentials are 6670 invalid. 6672 Use of the LOGIN command sends passwords in the clear. This can be 6673 avoided by using the AUTHENTICATE command with a [SASL] mechanism 6674 that does not use plaintext passwords, by first negotiating 6675 encryption via STARTTLS or some other protection mechanism. 6677 A server implementation MUST implement a configuration that, at the 6678 time of authentication, requires: 6679 (1) The STARTTLS command has been negotiated. 6680 OR 6681 (2) Some other mechanism that protects the session from password 6682 snooping has been provided. 6683 OR 6684 (3) The following measures are in place: 6685 (a) The LOGINDISABLED capability is advertised, and [SASL] mechanisms 6686 (such as PLAIN) using plaintext passwords are NOT advertised in the 6687 CAPABILITY list. 6688 AND 6689 (b) The LOGIN command returns an error even if the password is 6690 correct. 6691 AND 6692 (c) The AUTHENTICATE command returns an error with all [SASL] 6693 mechanisms that use plaintext passwords, even if the password is 6694 correct. 6696 A server error message for a failing LOGIN command SHOULD NOT specify 6697 that the user name, as opposed to the password, is invalid. 6699 A server SHOULD have mechanisms in place to limit or delay failed 6700 AUTHENTICATE/LOGIN attempts. 6702 Additional security considerations are discussed in the section 6703 discussing the AUTHENTICATE (see Section 6.2.2) and LOGIN (see 6704 Section 6.2.3) commands. 6706 12. IANA Considerations 6708 IANA is requested to update "Service Names and Transport Protocol 6709 Port Numbers" registry as follows: 6711 1. Registration for TCP port 143 and the corresponding "imap" 6712 service name should be updated to point to this document and RFC 6713 3501. 6715 2. Registration for TCP port 993 and the corresponding "imaps" 6716 service name should be updated to point to this document, RFC 6717 8314 and RFC 3501. 6719 3. Both UDP port 143 and UDP port 993 should be marked as "Reserved" 6720 in the registry. 6722 Additional IANA actions are specified in subsection of this section. 6724 12.1. Updates to IMAP4 Capabilities registry 6726 IMAP4 capabilities are registered by publishing a standards track or 6727 IESG approved informational or experimental RFC. The registry is 6728 currently located at: https://www.iana.org/assignments/ 6729 imap4-capabilities 6731 As this specification revises the AUTH= prefix, STARTTLS and 6732 LOGINDISABLED extensions previously defined in [IMAP-TLS], IANA is 6733 requested to update registry entries for these 3 extensions to point 6734 to this document. 6736 12.2. GSSAPI/SASL service name 6738 GSSAPI/Kerberos/SASL service names are registered by publishing a 6739 standards track or IESG approved experimental RFC. The registry is 6740 currently located at: https://www.iana.org/assignments/gssapi- 6741 service-names 6743 IANA is requested to update the "imap" service name previously 6744 registered in RFC 3501, to point to this document. 6746 12.3. LIST Selection Options, LIST Return Options, LIST extended data 6747 items 6749 [RFC5258] specifies IANA registration procedures for LIST Selection 6750 Options, LIST Return Options, LIST extended data items. This 6751 document doesn't change these registration procedures. In particular 6752 LIST selection options Section 6.3.9.1 and LIST return options 6753 Section 6.3.9.2 are registered using the procedure specified in 6754 Section 9 of [RFC5258] (and using the registration template from 6755 Section 9.3 of [RFC5258]). LIST Extended Data Items are registered 6756 using the registration template from Section 9.6 of [RFC5258]). 6758 IANA is requested to add a reference to [RFCXXXX] for the "OLDNAME" 6759 LIST-EXTENDED extended data item entry. This is in addition to the 6760 existing reference to [RFC5465]. 6762 13. References 6764 13.1. Normative References 6766 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access 6767 Protocol version 4 - LIST Command Extensions", RFC 5258, 6768 DOI 10.17487/RFC5258, June 2008, 6769 . 6771 [RFC5788] Melnikov, A. and D. Cridland, "IMAP4 Keyword Registry", 6772 RFC 5788, DOI 10.17487/RFC5788, March 2010, 6773 . 6775 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6776 Specifications: ABNF", STD 68, RFC 5234, January 2008, 6777 . 6779 [ANONYMOUS] 6780 Zeilenga, K., "Anonymous Simple Authentication and 6781 Security Layer (SASL) Mechanism", RFC 4505, June 2006, 6782 . 6784 [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration 6785 Procedures", BCP 19, RFC 2978, October 2000, 6786 . 6788 [SCRAM-SHA-256] 6789 Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple 6790 Authentication and Security Layer (SASL) Mechanisms", 6791 RFC 7677, DOI 10.17487/RFC7677, November 2015, 6792 . 6794 [DISPOSITION] 6795 Troost, R., Dorner, S., and K. Moore, Ed., "Communicating 6796 Presentation Information in Internet Messages: The 6797 Content-Disposition Header Field", RFC 2183, August 1997, 6798 . 6800 [PLAIN] Zeilenga, K., Ed., "The PLAIN Simple Authentication and 6801 Security Layer (SASL) Mechanism", RFC 4616, August 2006, 6802 . 6804 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6805 Requirement Levels", BCP 14, RFC 2119, 6806 DOI 10.17487/RFC2119, March 1997, 6807 . 6809 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 6810 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 6811 May 2017, . 6813 [LANGUAGE-TAGS] 6814 Alvestrand, H., "Content Language Headers", RFC 3282, May 6815 2002, . 6817 [LOCATION] 6818 Palme, J., Hopmann, A., and N. Shelness, "MIME 6819 Encapsulation of Aggregate Documents, such as HTML 6820 (MHTML)", RFC 2557, March 1999, 6821 . 6823 [MD5] Myers, J. and M. Rose, "The Content-MD5 Header Field", 6824 RFC 1864, October 1995, 6825 . 6827 [MIME-HDRS] 6828 Moore, K., "MIME (Multipurpose Internet Mail Extensions) 6829 Part Three: Message Header Extensions for Non-ASCII Text", 6830 RFC 2047, November 1996, 6831 . 6833 [MIME-IMB] 6834 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6835 Extensions (MIME) Part One: Format of Internet Message 6836 Bodies", RFC 2045, November 1996, 6837 . 6839 [MIME-IMT] 6840 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6841 Extensions (MIME) Part Two: Media Types", RFC 2046, 6842 November 1996, . 6844 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 6845 Word Extensions: Character Sets, Languages, and 6846 Continuations", RFC 2231, DOI 10.17487/RFC2231, November 6847 1997, . 6849 [RFC-5322] 6850 Resnick, P., Ed., "Internet Message Format", RFC 5322, 6851 October 2008, . 6853 [SASL] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 6854 Authentication and Security Layer (SASL)", RFC 4422, June 6855 2006, . 6857 [TLS] Dierks, T. and E. Rescorla, "The Transport Layer Security 6858 (TLS) Protocol Version 1.2", RFC 5246, August 2008, 6859 . 6861 [UTF-7] Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe 6862 Transformation Format of Unicode", RFC 2152, May 1997, 6863 . 6865 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 6866 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 6867 2003, . 6869 [MULTIAPPEND] 6870 Crispin, M., "Internet Message Access Protocol (IMAP) - 6871 MULTIAPPEND Extension", RFC 3502, March 2003, 6872 . 6874 [NET-UNICODE] 6875 Klensin, J. and M. Padlipsky, "Unicode Format for Network 6876 Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008, 6877 . 6879 [I18N-HDRS] 6880 Yang, A., Steele, S., and N. Freed, "Internationalized 6881 Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 6882 2012, . 6884 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 6885 Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, 6886 . 6888 [RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS) 6889 Server Identity Check Procedure for Email-Related 6890 Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016, 6891 . 6893 [RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition 6894 Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, 6895 February 2017, . 6897 [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: 6898 Use of Transport Layer Security (TLS) for Email Submission 6899 and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, 6900 . 6902 [IMAP-IMPLEMENTATION] 6903 Leiba, B., "IMAP4 Implementation Recommendations", 6904 RFC 2683, September 1999, 6905 . 6907 [IMAP-MULTIACCESS] 6908 Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", 6909 RFC 2180, July 1997, 6910 . 6912 13.2. Informative References (related protocols) 6914 [RFC3503] Melnikov, A., "Message Disposition Notification (MDN) 6915 profile for Internet Message Access Protocol (IMAP)", 6916 RFC 3503, DOI 10.17487/RFC3503, March 2003, 6917 . 6919 [RFC5256] Crispin, M. and K. Murchison, "Internet Message Access 6920 Protocol - SORT and THREAD Extensions", RFC 5256, 6921 DOI 10.17487/RFC5256, June 2008, 6922 . 6924 [RFC2193] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 6925 DOI 10.17487/RFC2193, September 1997, 6926 . 6928 [RFC3348] Gahrns, M. and R. Cheng, "The Internet Message Action 6929 Protocol (IMAP4) Child Mailbox Extension", RFC 3348, 6930 DOI 10.17487/RFC3348, July 2002, 6931 . 6933 [RFC5465] Gulbrandsen, A., King, C., and A. Melnikov, "The IMAP 6934 NOTIFY Extension", RFC 5465, DOI 10.17487/RFC5465, 6935 February 2009, . 6937 [RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals", 6938 RFC 7888, DOI 10.17487/RFC7888, May 2016, 6939 . 6941 [IMAP-DISC] 6942 Melnikov, A., Ed., "Synchronization Operations for 6943 Disconnected IMAP4 Clients", RFC 4549, June 2006, 6944 . 6946 [IMAP-I18N] 6947 Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 6948 Message Access Protocol Internationalization", RFC 5255, 6949 DOI 10.17487/RFC5255, June 2008, 6950 . 6952 [IMAP-MODEL] 6953 Crispin, M., "Distributed Electronic Mail Models in 6954 IMAP4", RFC 1733, December 1994, 6955 . 6957 [IMAP-UTF-8] 6958 Resnick, P., Ed., Newman, C., Ed., and S. Shen, Ed., "IMAP 6959 Support for UTF-8", RFC 6855, DOI 10.17487/RFC6855, March 6960 2013, . 6962 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 6963 October 2008, . 6965 [RFC3516] Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516, 6966 DOI 10.17487/RFC3516, April 2003, 6967 . 6969 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 6970 RFC 4314, December 2005, 6971 . 6973 [RFC2087] Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 6974 1997, . 6976 [IMAP-URL] 6977 Melnikov, A., Ed. and C. Newman, "IMAP URL Scheme", 6978 RFC 5092, DOI 10.17487/RFC5092, November 2007, 6979 . 6981 [IMAP-KEYWORDS-REG] 6982 IANA, "IMAP and JMAP Keywords", December 2009, 6983 . 6986 [IMAP-MAILBOX-NAME-ATTRS-REG] 6987 IANA, "IMAP Mailbox Name Attributes", June 2018, 6988 . 6991 [CHARSET-REG] 6992 IANA, "Character Set Registrations", May 2015, 6993 . 6996 13.3. Informative References (historical aspects of IMAP and related 6997 protocols) 6999 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 7000 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003, 7001 . 7003 [IMAP-COMPAT] 7004 Crispin, M., "IMAP4 Compatibility with IMAP2bis", 7005 RFC 2061, December 1996, 7006 . 7008 [IMAP-HISTORICAL] 7009 Crispin, M., "IMAP4 Compatibility with IMAP2 and 7010 IMAP2bis", RFC 1732, December 1994, 7011 . 7013 [IMAP-OBSOLETE] 7014 Crispin, M., "Internet Message Access Protocol - Obsolete 7015 Syntax", RFC 2062, December 1996, 7016 . 7018 [IMAP2] Crispin, M., "Interactive Mail Access Protocol: Version 7019 2", RFC 1176, August 1990, 7020 . 7022 [RFC-822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET 7023 TEXT MESSAGES", STD 11, RFC 822, August 1982, 7024 . 7026 [IMAP-TLS] 7027 Newman, C., "Using TLS with IMAP, POP3 and ACAP", 7028 RFC 2595, June 1999, 7029 . 7031 Appendix A. Backward compatibility with IMAP4rev1 7033 An implementation that wants to remain compatible with IMAP4rev1 can 7034 advertise both IMAP4rev1 and IMAP4rev2 in its CAPABILITY response/ 7035 response code. While some IMAP4rev1 responses were removed in 7036 IMAP4rev2, their presence will not break IMAP4rev2-only clients. 7038 If both IMAP4rev1 and IMAP4rev2 are advertised, an IMAP client that 7039 wants to use IMAP4rev2 MUST issue an "ENABLE IMAP4rev2" command. 7041 Servers advertising both IMAP4rev1 and IMAP4rev2 MUST NOT generate 7042 UTF-8 quoted strings unless the client has issued "ENABLE IMAP4rev2". 7043 Consider implementation of mechanisms described or referenced in 7044 [IMAP-UTF-8] to achieve this goal. 7046 Servers advertising both IMAP4rev1 and IMAP4rev2, and clients 7047 intending to be compatible with IMAP4rev1 servers MUST be compatible 7048 with the international mailbox naming convention described in the 7049 following subsection. 7051 A.1. Mailbox International Naming Convention for compatibility with 7052 IMAP4rev1 7054 Support for the Mailbox International Naming Convention described in 7055 this section is not required for IMAP4rev2-only clients and servers. 7057 By convention, international mailbox names in IMAP4rev1 are specified 7058 using a modified version of the UTF-7 encoding described in [UTF-7]. 7059 Modified UTF-7 may also be usable in servers that implement an 7060 earlier version of this protocol. 7062 In modified UTF-7, printable US-ASCII characters, except for "&", 7063 represent themselves; that is, characters with octet values 0x20-0x25 7064 and 0x27-0x7e. The character "&" (0x26) is represented by the two- 7065 octet sequence "&-". 7067 All other characters (octet values 0x00-0x1f and 0x7f-0xff) are 7068 represented in modified BASE64, with a further modification from 7069 [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be 7070 used to represent any printing US-ASCII character which can represent 7071 itself. Only characters inside the modified BASE64 alphabet are 7072 permitted in modified BASE64 text. 7074 "&" is used to shift to modified BASE64 and "-" to shift back to US- 7075 ASCII. There is no implicit shift from BASE64 to US-ASCII, and null 7076 shifts ("-&" while in BASE64; note that "&-" while in US-ASCII means 7077 "&") are not permitted. However, all names start in US-ASCII, and 7078 MUST end in US-ASCII; that is, a name that ends with a non-ASCII 7079 ISO-10646 character MUST end with a "-"). 7081 The purpose of these modifications is to correct the following 7082 problems with UTF-7: 7084 1. UTF-7 uses the "+" character for shifting; this conflicts with 7085 the common use of "+" in mailbox names, in particular USENET 7086 newsgroup names. 7088 2. UTF-7's encoding is BASE64 which uses the "/" character; this 7089 conflicts with the use of "/" as a popular hierarchy delimiter. 7091 3. UTF-7 prohibits the unencoded usage of "\"; this conflicts with 7092 the use of "\" as a popular hierarchy delimiter. 7094 4. UTF-7 prohibits the unencoded usage of "~"; this conflicts with 7095 the use of "~" in some servers as a home directory indicator. 7097 5. UTF-7 permits multiple alternate forms to represent the same 7098 string; in particular, printable US-ASCII characters can be 7099 represented in encoded form. 7101 Although modified UTF-7 is a convention, it establishes certain 7102 requirements on server handling of any mailbox name with an embedded 7103 "&" character. In particular, server implementations MUST preserve 7104 the exact form of the modified BASE64 portion of a modified UTF-7 7105 name and treat that text as case-sensitive, even if names are 7106 otherwise case-insensitive or case-folded. 7108 Server implementations SHOULD verify that any mailbox name with an 7109 embedded "&" character, used as an argument to CREATE, is: in the 7110 correctly modified UTF-7 syntax, has no superfluous shifts, and has 7111 no encoding in modified BASE64 of any printing US-ASCII character 7112 which can represent itself. However, client implementations MUST NOT 7113 depend upon the server doing this, and SHOULD NOT attempt to create a 7114 mailbox name with an embedded "&" character unless it complies with 7115 the modified UTF-7 syntax. 7117 Server implementations which export a mail store that does not follow 7118 the modified UTF-7 convention MUST convert to modified UTF-7 any 7119 mailbox name that contains either non-ASCII characters or the "&" 7120 character. 7122 For example, here is a mailbox name which mixes English, Chinese, 7123 and Japanese text: ~peter/mail/&U,BTFw-/&ZeVnLIqe- 7125 For example, the string "&Jjo!" is not a valid mailbox name 7126 because it does not contain a shift to US-ASCII before the "!". 7127 The correct form is "&Jjo-!". The string "&U,BTFw-&ZeVnLIqe-" is 7128 not permitted because it contains a superfluous shift. The 7129 correct form is "&U,BTF2XlZyyKng-". 7131 Appendix B. Backward compatibility with BINARY extension 7133 IMAP4rev2 is incorporates subset of functionality provided by the 7134 BINARY extension [RFC3516], in particular it includes additional 7135 FETCH items (BINARY, BINARY.PEEK and BINARY.SIZE), but not extensions 7136 to the APPEND command. IMAP4rev2 implementations that supports full 7137 RFC 3516 functionality need to also advertise the BINARY token in the 7138 CAPABILITY response. 7140 Appendix C. Backward compatibility with LIST-EXTENDED extension 7142 IMAP4rev2 is incorporates most of functionality provided by the LIST- 7143 EXTENDED extension [RFC5258]. In particular, multiple mailbox 7144 patterns syntax is not supported in IMAP4rev2, unless LIST-EXTENDED 7145 capability is also advertised in CAPABILITY response/response code. 7147 Appendix D. Changes from RFC 3501 / IMAP4rev1 7149 The following is the plan for remaining changes. The plan might 7150 change over time. 7152 1. Revise IANA registration of IMAP extensions and give advice on 7153 use of "X-" convention. 7155 2. Add a section on other recommended extensions? 7157 The following changes were already done: 7159 1. Fold in the following extensions/RFC: RFC 5530 (IMAP Response 7160 Codes), UIDPLUS, ENABLE, ESEARCH, SPECIAL-USE (list of new 7161 mailbox attributes), LITERAL-, NAMESPACE, SASL-IR, LIST-STATUS, 7162 SEARCHRES, IDLE, MOVE. 7164 2. Add CLOSED response code (from CONDSTORE). 7166 3. Add support for $Phishing, $Junk, $NonJunk, $MDNSent and 7167 $Forwarded IMAP keywords. Add more examples showing their use? 7169 4. Require all unsolicited FETCH updates to include UID. 7171 5. Update recommendations on TLS ciphers to match UTA WG work (as 7172 per RFC 8314, RFC 7525 and RFC 7817). 7174 6. Fold in the following extensions/RFC: Base LIST-EXTENDED syntax 7175 plus deprecate LSUB (replace it with LIST \Subscribed) minus the 7176 requirement to support multiple list patterns, BINARY (only the 7177 FETCH changes on leaf body part and make APPEND related ones 7178 optional. See the mailing list discussion). 7180 7. Add STATUS SIZE (total mailbox size). Add STATUS DELETED (number 7181 of messages with \Deleted flag set). 7183 8. Drop UTF-7, all mailboxes are always in UTF-8. 7185 The following changes since RFC 3501 were done so far: 7187 1. Folded in IMAP UNSELECT (RFC 3691), UIDPLUS (RFC 4315), ESEARCH 7188 (RFC 4731), SEARCHRES (RFC 5182), ENABLE (RFC 5161), IDLE (RFC 7189 2177), SASL-IR (RFC 4959), LIST-STATUS (RFC 5819) and MOVE (RFC 7190 6851) extensions. Also folded RFC 5530 and FETCH side of the 7191 BINARY extension (RFC 3516). 7193 2. Clarified that server should decode parameter value 7194 continuations as described in [RFC2231]. This requirement was 7195 hidden in RFC 2231 itself. 7197 3. SEARCH command now requires to return ESEARCH response (SEARCH 7198 response is now deprecated). 7200 4. Clarified which SEARCH keys has to use substring match and which 7201 don't. 7203 5. Added CLOSED response code from RFC 7162. SELECT/EXAMINE when a 7204 mailbox is already selected now require for the CLOSED response 7205 code to be returned. 7207 6. Updated to use modern TLS-related recommendations as per RFC 7208 8314, RFC 7817, RFC 7525. 7210 7. For future extensibility extended ABNF for tagged-ext-simple to 7211 allow for bare number64. 7213 8. Added SHOULD level requirement on IMAP servers to support 7214 $MDNSent, $Forwarded, $Junk, $NonJunk and $Phishing keywords. 7216 9. Added STATUS SIZE (RFC 8438) and STATUS DELETED. 7218 10. Mailbox names and message headers now allow for UTF-8. Support 7219 for Modified UTF-7 in mailbox names is not required, unless 7220 compatibility with IMAP4rev1 is desired. 7222 11. UNSEEN response code on SELECT/EXAMINE is now deprecated. 7224 12. RECENT response on SELECT/EXAMINE, \Recent flag, RECENT STATUS, 7225 SEARCH NEW items are now deprecated. 7227 13. Clarified that the server doesn't need to send a new 7228 PERMANENTFLAGS response code when a new keyword was successfully 7229 added and the server advertised \* earlier for the same mailbox. 7231 14. Removed the CHECK command. Clients should use NOOP instead. 7233 15. RFC822, RFC822.HEADER and RFC822.TEXT FETCH data items were 7234 deprecated. Clients should use the corresponding BODY[] 7235 variants instead. 7237 16. Replaced DIGEST-MD5 SASL mechanism with SCRAM-SHA-256. DIGEST- 7238 MD5 was deprecated. 7240 17. LSUB command was deprecated. Clients should use LIST 7241 (SUBSCRIBED) instead. 7243 18. resp-text ABNF non terminal was updated to allow for empty text. 7245 19. IDLE command can now return updates not related to the currently 7246 selected mailbox state. 7248 20. All unsolicited FETCH updates are required to include UID. 7250 21. Clarified that client implementations MUST ignore response codes 7251 that they do not recognize. (Change from a SHOULD to a MUST.) 7253 22. After ENABLE IMAP4rev2 human readable response text can include 7254 non ASCII encoded in UTF-8. 7256 Appendix E. Acknowledgement 7258 Earlier versions of this document were edited by Mark Crispin. 7259 Sadly, he is no longer available to help with this work. Editors of 7260 this revisions are hoping that Mark would have approved. 7262 Chris Newman has contributed text on I18N and use of UTF-8 in 7263 messages and mailbox names. 7265 Thank you to Tony Hansen for helping with the index generation. 7266 Thank you to Timo Sirainen, Bron Gondwana, Stephan Bosch and Arnt 7267 Gulbrandsen for extensive feedback. 7269 This document incorporate text from RFC 4315 (by Mark Crispin), RFC 7270 4466 (by Cyrus Daboo), RFC 4731 (by Dave Cridland), RFC 5161 (by Arnt 7271 Gulbrandsen), RFC 5465 (by Arnt Gulbrandsen and Curtis King), RFC 7272 5530 (by Arnt Gulbrandsen), RFC 5819 (by Timo Sirainen), RFC 6154 (by 7273 Jamie Nicolson), RFC 8438 (by Stephan Bosch) so work done by authors/ 7274 editors of these documents is appreciated. Note that editors of this 7275 document were redacted from the above list. 7277 The CHILDREN return option was originally proposed by Mike Gahrns and 7278 Raymond Cheng in [RFC3348]. Most of the information in 7279 Section 6.3.9.5 is taken directly from their original specification 7280 [RFC3348]. 7282 Index 7284 $ 7285 $Forwarded (predefined flag) 12 7286 $Junk (predefined flag) 12 7287 $MDNSent (predefined flag) 12 7288 $NotJunk (predefined flag) 12 7289 $Phishing (predefined flag) 12 7291 + 7292 +FLAGS 92 7293 +FLAGS.SILENT 92 7295 - 7296 -FLAGS 92 7297 -FLAGS.SILENT 92 7299 A 7300 ALERT (response code) 99 7301 ALL (fetch item) 88 7302 ALL (search key) 78 7303 ALL (search result option) 76 7304 ALREADYEXISTS (response code) 99 7305 ANSWERED (search key) 78 7306 APPEND (command) 68 7307 APPENDUID (response code) 99 7308 AUTHENTICATE (command) 29 7309 AUTHENTICATIONFAILED (response code) 100 7310 AUTHORIZATIONFAILED (response code) 100 7312 B 7313 BAD (response) 108 7314 BADCHARSET (response code) 101 7315 BCC (search key) 78 7316 BEFORE (search key) 78 7317 BINARY.PEEK[]<> (fetch item) 88 7318 BINARY.SIZE[] (fetch item) 88 7319 BINARY.SIZE[] (fetch result) 118 7320 BINARY[]<> (fetch result) 117 7321 BINARY[]<> (fetch item) 88 7322 BODY (fetch item) 89 7323 BODY (fetch result) 118 7324 BODY (search key) 78 7325 BODY.PEEK[
]<> (fetch item) 91 7326 BODYSTRUCTURE (fetch item) 91 7327 BODYSTRUCTURE (fetch result) 119 7328 BODY[
]<> (fetch result) 118 7329 BODY[
]<> (fetch item) 89 7330 BYE (response) 108 7331 Body Structure (message attribute) 14 7333 C 7334 CANNOT (response code) 101 7335 CAPABILITY (command) 25 7336 CAPABILITY (response code) 101 7337 CAPABILITY (response) 109 7338 CC (search key) 78 7339 CLIENTBUG (response code) 101 7340 CLOSE (command) 73 7341 CLOSED (response code) 102 7342 CONTACTADMIN (response code) 102 7343 COPY (command) 93 7344 COPYUID (response code) 102 7345 CORRUPTION (response code) 102 7346 COUNT (search result option) 76 7347 CREATE (command) 38 7349 D 7350 DELETE (command) 39 7351 DELETED (search key) 78 7352 DELETED (status item) 68 7353 DRAFT (search key) 78 7355 E 7356 ENABLE (command) 33 7357 ENVELOPE (fetch item) 91 7358 ENVELOPE (fetch result) 121 7359 ESEARCH (response) 115 7360 EXAMINE (command) 37 7361 EXPIRED (response code) 103 7362 EXPUNGE (command) 74 7363 EXPUNGE (response) 116 7364 EXPUNGEISSUED (response code) 103 7365 Envelope Structure (message attribute) 14 7367 F 7368 FAST (fetch item) 88 7369 FETCH (command) 87 7370 FETCH (response) 117 7371 FLAGGED (search key) 78 7372 FLAGS (fetch item) 91 7373 FLAGS (fetch result) 123 7374 FLAGS (response) 115 7375 FLAGS (store command data item) 92 7376 FLAGS.SILENT (store command data item) 92 7377 FROM (search key) 78 7378 FULL (fetch item) 88 7379 Flags (message attribute) 11 7381 H 7382 HASCHILDREN (response code) 103 7383 HEADER (part specifier) 89 7384 HEADER (search key) 78 7385 HEADER.FIELDS (part specifier) 89 7386 HEADER.FIELDS.NOT (part specifier) 89 7388 I 7389 IDLE (command) 71 7390 INTERNALDATE (fetch item) 91 7391 INTERNALDATE (fetch result) 123 7392 INUSE (response code) 103 7393 Internal Date (message attribute) 13 7395 K 7396 KEYWORD (search key) 79 7397 Keyword (type of flag) 12 7399 L 7400 LARGER (search key) 79 7401 LIMIT (response code) 104 7402 LIST (command) 44 7403 LIST (response) 110 7404 LOGOUT (command) 27 7406 M 7407 MAX (search result option) 76 7408 MAY (specification requirement term) 5 7409 MESSAGES (status item) 68 7410 MIME (part specifier) 90 7411 MIN (search result option) 76 7412 MOVE (command) 94 7413 MUST (specification requirement term) 5 7414 MUST NOT (specification requirement term) 5 7415 Message Sequence Number (message attribute) 11 7417 N 7418 NAMESPACE (command) 62 7419 NAMESPACE (response) 114 7420 NO (response) 107 7421 NONEXISTENT (response code) 104 7422 NOOP (command) 26 7423 NOPERM (response code) 104 7424 NOT (search key) 79 7425 NOT RECOMMENDED (specification requirement term) 5 7427 O 7428 OK (response) 107 7429 ON (search key) 79 7430 OPTIONAL (specification requirement term) 5 7431 OR (search key) 79 7432 OVERQUOTA (response code) 104 7434 P 7435 PARSE (response code) 104 7436 PERMANENTFLAGS (response code) 105 7437 PREAUTH (response) 108 7438 PRIVACYREQUIRED (response code) 105 7439 Permanent Flag (class of flag) 13 7440 Predefined keywords 12 7442 R 7443 READ-ONLY (response code) 105 7444 READ-WRITE (response code) 105 7445 RECOMMENDED (specification requirement term) 5 7446 RENAME (command) 41 7447 REQUIRED (specification requirement term) 5 7448 RFC822.SIZE (fetch item) 91 7449 RFC822.SIZE (fetch result) 123 7451 S 7452 SAVE (search result option) 76 7453 SEARCH (command) 75 7454 SEEN (search key) 79 7455 SELECT (command) 35 7456 SENTBEFORE (search key) 79 7457 SENTON (search key) 79 7458 SENTSINCE (search key) 79 7459 SERVERBUG (response code) 106 7460 SHOULD (specification requirement term) 5 7461 SHOULD NOT (specification requirement term) 5 7462 SINCE (search key) 79 7463 SIZE (status item) 68 7464 SMALLER (search key) 79 7465 STARTTLS (command) 28 7466 STATUS (command) 67 7467 STATUS (response) 115 7468 STORE (command) 91 7469 SUBJECT (search key) 79 7470 SUBSCRIBE (command) 43 7471 Session Flag (class of flag) 13 7472 System Flag (type of flag) 11 7474 T 7475 TEXT (part specifier) 89 7476 TEXT (search key) 79 7477 TO (search key) 80 7478 TRYCREATE (response code) 106 7480 U 7481 UID (command) 95 7482 UID (fetch item) 91 7483 UID (fetch result) 123 7484 UID (search key) 80 7485 UIDNEXT (response code) 106 7486 UIDNEXT (status item) 68 7487 UIDNOTSTICKY (response code) 106 7488 UIDVALIDITY (response code) 106 7489 UIDVALIDITY (status item) 68 7490 UNANSWERED (search key) 80 7491 UNAVAILABLE (response code) 106 7492 UNDELETED (search key) 80 7493 UNDRAFT (search key) 80 7494 UNFLAGGED (search key) 80 7495 UNKEYWORD (search key) 80 7496 UNKNOWN-CTE (response code) 107 7497 UNSEEN (search key) 80 7498 UNSEEN (status item) 68 7499 UNSELECT (command) 74 7500 UNSUBSCRIBE (command) 44 7501 Unique Identifier (UID) (message attribute) 9 7503 X 7504 X (command) 97 7506 [ 7507 [RFC-5322] Size (message attribute) 14 7509 \ 7510 \All (mailbox name attribute) 112 7511 \Answered (system flag) 11 7512 \Archive (mailbox name attribute) 112 7513 \Deleted (system flag) 12 7514 \Draft (system flag) 12 7515 \Drafts (mailbox name attribute) 113 7516 \Flagged (mailbox name attribute) 113 7517 \Flagged (system flag) 11 7518 \HasChildren (mailbox name attribute) 111 7519 \HasNoChildren (mailbox name attribute) 112 7520 \Junk (mailbox name attribute) 113 7521 \Marked (mailbox name attribute) 112 7522 \Noinferiors (mailbox name attribute) 111 7523 \NonExistent (mailbox name attribute) 111 7524 \Noselect (mailbox name attribute) 111 7525 \Recent (system flag) 12 7526 \Remote (mailbox name attribute) 112 7527 \Seen (system flag) 11 7528 \Sent (mailbox name attribute) 113 7529 \Subscribed (mailbox name attribute) 112 7530 \Trash (mailbox name attribute) 113 7531 \Unmarked (mailbox name attribute) 112 7533 Authors' Addresses 7535 Alexey Melnikov (editor) 7536 Isode Ltd 7537 14 Castle Mews 7538 Hampton, Middlesex TW12 2NP 7539 UK 7541 Email: Alexey.Melnikov@isode.com 7543 Barry Leiba (editor) 7544 Futurewei Technologies 7546 Phone: +1 646 827 0648 7547 Email: barryleiba@computer.org 7548 URI: http://internetmessagingtechnology.org/