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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 3501 (Obsoleted by RFC 9051) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Sieve Working Group B. Leiba 3 Internet-Draft Huawei Technologies 4 Intended status: Standards Track July 14, 2012 5 Expires: January 15, 2013 7 Support for Internet Message Access Protocol (IMAP) Events in Sieve 8 draft-ietf-sieve-imap-sieve-06 10 Abstract 12 Sieve defines an email filtering language that can, in principle, 13 plug into any point in the processing of an email message. As 14 defined in the base specification, it plugs into mail delivery. This 15 document defines how Sieve can plug into points in the IMAP protocol 16 where messages are created or changed, adding the option of user- 17 defined or installation-defined filtering (or, with Sieve extensions, 18 features such as notifications). 20 Status of this Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on January 15, 2013. 37 Copyright Notice 39 Copyright (c) 2012 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 4 55 1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 4 56 1.2. Differences Between IMAP Events and Mail Delivery . . . . 4 57 1.3. Conventions used in this document . . . . . . . . . . . . 5 59 2. The IMAP Events in Sieve Extension . . . . . . . . . . . . 6 60 2.1. The "imapsieve" Capability Strings . . . . . . . . . . . . 6 61 2.2. Existing IMAP Functions Affected by IMAP events in 62 Sieve . . . . . . . . . . . . . . . . . . . . . . . . . . 6 63 2.2.1. The IMAP APPEND Command . . . . . . . . . . . . . . . . . 7 64 2.2.2. The IMAP MULTIAPPEND Command . . . . . . . . . . . . . . . 7 65 2.2.3. The IMAP COPY Command . . . . . . . . . . . . . . . . . . 7 66 2.2.4. Changes to IMAP Message Flags . . . . . . . . . . . . . . 7 67 2.3. New Functions Defined by IMAP events in Sieve . . . . . . 8 68 2.3.1. Interaction with Metadata . . . . . . . . . . . . . . . . 8 70 3. Applicable Sieve Actions and Interactions . . . . . . . . 10 71 3.1. The Implicit Keep . . . . . . . . . . . . . . . . . . . . 10 72 3.2. The Keep Action . . . . . . . . . . . . . . . . . . . . . 10 73 3.3. The Fileinto Action . . . . . . . . . . . . . . . . . . . 10 74 3.4. The Redirect Action . . . . . . . . . . . . . . . . . . . 11 75 3.5. The Discard Action . . . . . . . . . . . . . . . . . . . . 11 76 3.6. The Notify Action . . . . . . . . . . . . . . . . . . . . 12 77 3.7. The Addheader and Deleteheader Actions . . . . . . . . . . 12 78 3.8. The Setflag, Deleteflag, and Removeflag Actions . . . . . 12 79 3.9. MIME Part Tests and Replacement . . . . . . . . . . . . . 12 80 3.10. Spamtest and Virustest . . . . . . . . . . . . . . . . . . 13 81 3.11. Inapplicable Actions . . . . . . . . . . . . . . . . . . . 13 83 4. Interaction With Sieve Environment . . . . . . . . . . . . 14 84 4.1. Base Sieve Environment Items: location and phase . . . . . 14 85 4.2. New Sieve Environment Items: imapuser and imapemail . . . 14 86 4.3. New Sieve Environment Item: cause . . . . . . . . . . . . 14 87 4.4. New Sieve Environment Item: mailbox . . . . . . . . . . . 15 88 4.5. New Sieve Environment Item: changedflags . . . . . . . . . 15 89 4.6. Interaction With Sieve Tests (Comparisons) . . . . . . . . 15 91 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 16 93 6. Security Considerations . . . . . . . . . . . . . . . . . 17 95 7. IANA Considerations . . . . . . . . . . . . . . . . . . . 18 96 7.1. Registration of "imapsieve" IMAP capability . . . . . . . 18 97 7.2. Registration of "imapsieve" Sieve extension . . . . . . . 18 98 7.3. Registration of Sieve Environment Items . . . . . . . . . 18 99 7.3.1. Registration of Sieve Environment Item: cause . . . . . . 18 100 7.3.2. Registration of Sieve Environment Item: mailbox . . . . . 19 101 7.3.3. Registration of Sieve Environment Item: changedflags . . . 19 102 7.3.4. Registration of Sieve Environment Item: imapuser . . . . . 19 103 7.3.5. Registration of Sieve Environment Item: imapemail . . . . 19 104 7.4. Registration of IMAP METADATA Mailbox Entry Name . . . . . 19 105 7.5. Registration of IMAP METADATA Server Entry Name . . . . . 20 107 8. References . . . . . . . . . . . . . . . . . . . . . . . . 21 108 8.1. Normative References . . . . . . . . . . . . . . . . . . . 21 109 8.2. Informative References . . . . . . . . . . . . . . . . . . 21 111 Author's Address . . . . . . . . . . . . . . . . . . . . . 23 113 1. Introduction 115 1.1. Overview 117 Some applications have a need to apply Sieve filters [RFC5228] in 118 contexts other than initial mail delivery. This is especially true 119 in diverse service environments, such as when the client is 120 sporadically connected, is connected through a high-latency or high- 121 cost channel, or is on a limited-function device. For such clients, 122 it may be very important, for higher performance and reliability, to 123 take advantage of server capabilities, including those provided by 124 Sieve filtering (and Sieve extensions, such as Notify [RFC5435]). 126 This specification defines extensions to IMAP [RFC3501] to support 127 the invocation of Sieve scripts at times when the IMAP server creates 128 new messages or modifies existing ones. It also defines how Sieve 129 scripts will process these invocations. Support for IMAP events in 130 Sieve requires support for IMAP Metadata [RFC5464] and Sieve 131 Environment [RFC5183] as well, because Metadata is used to associate 132 scripts with IMAP mailboxes and Environment defines an important way 133 for Sieve scripts to test the conditions under which they have been 134 invoked. 136 1.2. Differences Between IMAP Events and Mail Delivery 138 Invoking Sieve scripts in a context other than initial mail delivery 139 introduces new situations, which changes the applicability of Sieve 140 features and creates implementation challenges and user interface 141 issues. This section discusses some of those differences, 142 challenges, and issues. 144 At times other than message delivery, delivery "envelope" information 145 might not be available. With messages added through IMAP APPEND, 146 there might be no way to even guess who the intended recipient is, 147 and no concept of who "sent" the message. Sieve actions that relate 148 to contacting the sender, for example, will not be applicable. 150 Because IMAP events will often be triggered by user actions, and 151 because user interfaces allow bulk actions that differ from 152 individual message arrival, it now becomes possible for a single user 153 action, such as drag-and-drop, to initiate Sieve script processing on 154 a large number of messages at once. Implementations will have to 155 deal with such situations as a "COPY" action or flag changes on 156 dozens, or even thousands of messages. 158 Other issues might surface as this extension is deployed and 159 experience with it develops. 161 1.3. Conventions used in this document 163 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 164 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 165 document are to be interpreted as described in [RFC2119]. 167 2. The IMAP Events in Sieve Extension 169 2.1. The "imapsieve" Capability Strings 171 An IMAP server advertises support for IMAP events in Sieve through 172 the "imapsieve" capability. A server that advertises "imapsieve" is 173 claiming to be in compliance with this specification in all aspects. 174 The syntax of the "imapsieve" capability string is defined as 175 follows: 177 capability /= "IMAPSIEVE=" sieveurl-server 178 ; is defined in RFC 5804, Section 3 180 Only one "imapsieve" capability string, specifying one sieveurl- 181 server, can be present. The sieveurl-server identifies the 182 ManageSieve server that clients need to contact for managing Sieve 183 scripts associated with this IMAP server. 185 The corresponding Sieve implementation uses the Sieve capability 186 string "imapsieve", and Sieve scripts that depend upon the IMAP 187 events MUST include that string in their "required" lists. 189 Implementations that support IMAP events in Sieve MUST also support 190 IMAP Metadata [RFC5464] and Sieve Environment [RFC5183], because 191 Metadata is used to associate scripts with IMAP mailboxes and 192 Environment defines an important way for Sieve scripts to test the 193 conditions under which they have been invoked. Notwithstanding the 194 support requirement, scripts that directly use Environment MUST also 195 include its capability string in their "required" lists. 197 2.2. Existing IMAP Functions Affected by IMAP events in Sieve 199 The subsections below describe in detail the IMAP commands and 200 situations on which IMAP events in Sieve have an effect. Not all 201 Sieve actions make sense in the case of messages affected by IMAP 202 commands. See Section 3 for details. 204 It's important to note that since the base Sieve specification (see 205 [RFC5228]) and its extensions define functions for scripts that are 206 invoked during initial mail delivery, those function definitions are 207 necessarily tailored to and limited by that context. This document 208 extends those function definitions for use during IMAP events. By 209 nature of that, Sieve functions, in this extended context, may behave 210 somewhat differently, though their extended behaviour will still be 211 consistent with the functions' goals. 213 If more than one message is affected at the same time, each message 214 triggers the execution of a Sieve script separately. The scripts MAY 215 be run in parallel. 217 2.2.1. The IMAP APPEND Command 219 A message may be added to a mailbox through the IMAP APPEND command. 220 In a server that advertises "imapsieve", new messages added in this 221 way MUST trigger the execution of a Sieve script, subject to the 222 settings defined through Metadata (see Section 2.3.1). 224 2.2.2. The IMAP MULTIAPPEND Command 226 If the IMAP server supports the IMAP MultiAppend extension [RFC3502], 227 messages may be added to a mailbox through the IMAP MULTIAPPEND 228 command. In a server that advertises "imapsieve", new messages added 229 in this way MUST trigger the execution of a Sieve script, as with the 230 APPEND command, also subject to the settings defined through 231 Metadata. 233 2.2.3. The IMAP COPY Command 235 One or more messages may be added to a mailbox through the IMAP COPY 236 command. In a server that advertises "imapsieve", new messages added 237 in this way MUST trigger the execution of a Sieve script, subject to 238 the settings defined through Metadata. 240 2.2.4. Changes to IMAP Message Flags 242 One or more existing messages can have their flags changed in a 243 number of ways, including: 245 o The FETCH command (may cause the \Seen flag to be set). 247 o The STORE command (may cause the \Answered, \Deleted, \Draft, 248 \Flagged, and \Seen flags to be set or reset, and may cause 249 keywords to be set or reset). 251 o The invocation of a Sieve script on an existing message, where the 252 Sieve implementation supports the IMAP4Flags extension [RFC5232] 253 and the script uses one of the actions defined in that extension. 255 In a server that advertises "imapsieve", messages whose flags are 256 changed in any way (except as explained in the next sentence) MUST 257 trigger the execution of a Sieve script, subject to the settings 258 defined through Metadata. The exception is that in order to avoid 259 script loops, flag changes that are made as a result of a script that 260 was itself invoked because of flag changes SHOULD NOT result in 261 another script invocation. In any case, implementations MUST take 262 steps to avoid such loops. 264 For flag-change events, the Sieve script will see the message flags 265 as they are AFTER the changes. 267 2.3. New Functions Defined by IMAP events in Sieve 269 2.3.1. Interaction with Metadata 271 Support for IMAP events in Sieve requires support for IMAP Metadata 272 [RFC5464] as well, since the latter is used to associate scripts with 273 IMAP mailboxes. 275 When an applicable event occurs on an IMAP mailbox, if there is an 276 IMAP metadata entry named "/shared/imapsieve/script" for the mailbox, 277 that entry is used. If there is not, but there is an IMAP metadata 278 entry named "/shared/imapsieve/script" for the server, that entry is 279 used (providing a way to define a global script for all mailboxes on 280 a server). If neither entry exists, then no script will be invoked. 282 If a "/shared/imapsieve/script" metadata entry was selected above, 283 its value is used as the name of the Sieve script that will be 284 invoked in response to the IMAP event. If the value is empty, then 285 no script is run. 287 This specifies the mechanism for "activating" a script for a given 288 mailbox (or for all mailboxes), but does not specify a mechanism for 289 creating, storing, or validating the script. Implementations MUST 290 support ManageSieve [RFC5804], and can use the PUTSCRIPT command to 291 store the script without using the SETACTIVE command to activate it. 293 Script names used in "/shared/imapsieve/script" metadata entries are 294 the script names used on the corresponding ManageSieve server. If a 295 "/shared/imapsieve/script" metadata entry contains a script name that 296 doesn't exist in the ManageSieve server, then no Sieve script will be 297 invoked for IMAP Sieve events. 299 Only one Sieve script may currently be defined per mailbox, 300 eliminating the complexity and possible ambiguity involved with 301 coordinating the results of multiple scripts. Any sub-filtering is 302 done in the Sieve script. For example, if it's only necessary to 303 deal with flag changes, but not with new messages appended or copied, 304 the Sieve script will still be invoked for all events, and the script 305 is responsible for checking the event type. 307 The possibility is open for an extension to add support for multiple 308 scripts -- for example, per-client scripts on a multi-client user's 309 inbox, or per-user scripts on a mailbox that is shared among users. 311 Because this metadata name is associated with the mailbox, there can 312 (and it's expected that there will) be different scripts associated 313 with events for different mailboxes. Indeed, most mailboxes will 314 probably invoke no script at all. 316 3. Applicable Sieve Actions and Interactions 318 Since some Sieve actions relate specifically to the delivery of mail, 319 not all actions and extensions make sense when the messages are 320 created by other means or when changes are made to data associated 321 with existing messages. This section describes how actions in the 322 base Sieve specification, and those in extensions known at this 323 writing, relate to this specification. 325 In addition to what is specified here, interactions noted in the 326 individual specifications apply, and must be considered. 328 3.1. The Implicit Keep 330 For all cases that fall under IMAP events in Sieve, the implicit keep 331 means that the message is treated as it would have been if no Sieve 332 script were run. For APPEND, MULTIAPPEND and COPY, the message is 333 stored into the target mailbox normally. For flag changes, the 334 message is left in the mailbox. If actions have been taken that 335 change the message, those changes are considered transient and MUST 336 NOT be retained for any keep action (because IMAP messages are 337 immutable). No error is generated, but the original message, without 338 the changes, is kept. 340 3.2. The Keep Action 342 The keep action is applicable in all cases that fall under IMAP 343 events in Sieve. Its behaviour is as described for implicit keep, in 344 Section 3.1. 346 3.3. The Fileinto Action 348 If the Sieve implementation supports the fileinto action, that action 349 is applicable in all cases that fall under IMAP events in Sieve. If 350 the Copy extension [RFC3894] is available and the :copy option is 351 specified, the implicit keep is retained; otherwise, fileinto cancels 352 the implicit keep, as specified in the base Sieve specification. 354 For APPEND, MULTIAPPEND, and COPY, the message is stored into the 355 fileinto mailbox IN ADDITION TO the original target mailbox. For 356 flag changes, the message is COPIED into the fileinto mailbox, 357 without removing the original. In all cases, fileinto always creates 358 a new message, separate from the original. 360 If a keep action is NOT also in effect, the original message is then 361 marked with the \Deleted flag (and a flag-change Sieve script is NOT 362 invoked). The implementation MAY then expunge the original message 363 (WITHOUT expunging other messages in the mailbox), or it MAY choose 364 to have expunges batched, or done by a user. If the server does the 365 expunge, the effect is as though a client had flagged the message and 366 done a UID EXPUNGE (see [RFC4315]) on the affected message(s) only. 367 Handling it this way allows clients to handle messages consistently, 368 and avoids hidden changes that might invalidate their message caches. 370 3.4. The Redirect Action 372 The redirect action is applicable in all cases that fall under IMAP 373 events in Sieve. It causes the message to be sent, as specified in 374 the base Sieve specification, to the designated address. If the Copy 375 extension [RFC3894] is available and the :copy option is specified, 376 the implicit keep is retained; otherwise, redirect cancels the 377 implicit keep, as specified in the base Sieve specification. 379 It's possible that a message processed in this way does not have the 380 information necessary to be redirected properly. It might lack 381 necessary header information, and there might not be appropriate 382 information for the MAIL FROM command. In such cases, the "redirect" 383 action uses Message Submission [RFC6409], and it is up to the Sieve 384 engine to supply the missing information. The redirect address is, 385 of course, used for the "RCPT TO", and the "MAIL FROM" SHOULD be set 386 to the address of the owner of the mailbox. The message submission 387 server is allowed, according to the Message Submission protocol, to 388 perform necessary fix-up to the message (see Section 8 of RFC 6409). 389 It can also reject the submission attempt, if the message is too ill- 390 formed for submission. 392 For APPEND, MULTIAPPEND, and COPY, the message is stored into the 393 target mailbox in addition to being redirected. For flag changes, 394 the message remains in its original mailbox. 396 If a keep action is NOT also in effect, the original message is then 397 marked with the \Deleted flag (and a flag-change Sieve script is NOT 398 invoked). The implementation MAY then expunge the original message 399 (WITHOUT expunging other messages in the mailbox), or it MAY choose 400 to have expunges batched, or done by a user. If the server does the 401 expunge, the effect is as though a client had flagged the message and 402 done a UID EXPUNGE (see [RFC4315]) on the affected message(s) only. 403 Handling it this way allows clients to handle messages consistently, 404 and avoids hidden changes that might invalidate their message caches. 406 3.5. The Discard Action 408 The discard action is applicable in all cases that fall under IMAP 409 events in Sieve. For APPEND, MULTIAPPEND, and COPY, the message is 410 first stored into the target mailbox. If an explicit keep action is 411 also in effect, the discard action now does nothing. Otherwise, the 412 original message is then marked with the \Deleted flag (and a flag- 413 change Sieve script is NOT invoked). The implementation MAY then 414 expunge the original message (WITHOUT expunging other messages in the 415 mailbox), or it MAY choose to have expunges batched, or done by a 416 user. If the server does the expunge, the effect is as though a 417 client had flagged the message and done a UID EXPUNGE (see [RFC4315]) 418 on the affected message(s) only. Handling it this way allows clients 419 to handle messages consistently, and avoids hidden changes that might 420 invalidate their message caches. 422 3.6. The Notify Action 424 If the Nofity extension [RFC5435] is available, the notify action is 425 applicable in all cases that fall under IMAP events in Sieve. The 426 result is that the requested notification is sent, and that the 427 message is otherwise handled as it would normally have been. 429 3.7. The Addheader and Deleteheader Actions 431 If the EditHeader extension [RFC5293] is available, it can be used to 432 make transient changes to header fields, which aren't saved in place, 433 such as for "redirect" or "fileinto" actions. Because messages in 434 IMAP mailboxes are immutable, such changes are NOT applicable for the 435 "keep" acton (explicit or implicit). See Section 3.1. 437 3.8. The Setflag, Deleteflag, and Removeflag Actions 439 Implementations of IMAP events in Sieve MUST also support the 440 IMAP4Flags extension [RFC5232], and the actions associated with it 441 are all applicable to any case that falls under IMAP events in Sieve. 443 It is worth noting also that the "hasflag" test that is defined in 444 the IMAP4Flags extension might be particularly useful in scripts 445 triggered by flag changes ("hasflag" will see the new, changed 446 flags). The flag changes behave as though a client had made the 447 change. 449 As explained above, in order to avoid script loops flag changes that 450 are made as a result of a script that was itself invoked because of 451 flag changes SHOULD NOT result in another script invocation. In any 452 case, implementations MUST take steps to avoid such loops. 454 3.9. MIME Part Tests and Replacement 456 If the MIME Part Tests extension [RFC5703] is available, all of its 457 functions can be used, but any changes made to the message, using the 458 "replace" or "enclose" action, MUST be considered transient, and are 459 only applicable with actions such as "redirect" and "fileinto". 461 Because messages in IMAP mailboxes are immutable, such changes are 462 NOT applicable for the "keep" acton (explicit or implicit). See 463 Section 3.1. 465 3.10. Spamtest and Virustest 467 If the Spamtest and Virustest extensions [RFC5235] are available, 468 they are applicable in all cases that fall under IMAP events in 469 Sieve. 471 3.11. Inapplicable Actions 473 The following actions and extensions are NOT applicable to any case 474 that falls under IMAP events in Sieve, because they are specifically 475 designed to respond to delivery of a new email message. Their 476 appearance in the "require" control or their use in an IMAP event 477 MUST result in an error condition that will terminate the Sieve 478 script: 480 reject [RFC5228] 482 ereject [RFC5429] 484 vacation [RFC5230] 486 Future extensions that are specifically designed to respond to 487 delivery of a new email message will likewise not be applicable to 488 this extension. 490 4. Interaction With Sieve Environment 492 4.1. Base Sieve Environment Items: location and phase 494 The Sieve Environment extension defines a set of standard environment 495 items (see [RFC5183], Section 4.1). Two of those items are affected 496 when the script is invoked through an IMAP event. 498 The value of "location" is set to "MS" -- evaluation is being 499 performed by a Message Store. 501 The value of "phase" is set to "post" -- processing is taking place 502 after (or perhaps instead of, in the case of APPEND) final delivery. 504 4.2. New Sieve Environment Items: imapuser and imapemail 506 In the normal case, when Sieve is used in final delivery, there is no 507 identity for the "filer" -- the user who is creating or changing the 508 message. In this case, there is such an identity, and a Sieve script 509 might want to access that identity. 511 Implementations MUST set and make available two new environment 512 items: 514 "imapuser" -- the identity (login ID) of the IMAP user that caused 515 the action. This MUST be the empty string if it is accessed during 516 normal (final delivery) Sieve processing. 518 "imapemail" -- the primary email address of the IMAP user that caused 519 the action (the user identified by "imapuser"). In some 520 implementations, "imapuser" and "imapemail" might have the same 521 value. This MUST be the empty string if it is accessed during normal 522 (final delivery) Sieve processing. 524 4.3. New Sieve Environment Item: cause 526 Each mailbox uses a single script for all the change conditions 527 described in this document (append, copy, flag changes). To support 528 that, the implementation MUST set the Environment [RFC5183] item 529 "cause", which contains the name of the action that caused the script 530 to be invoked. Its value is one of the following: 532 o APPEND (for invocations resulting from APPEND or MULTIAPPEND) 534 o COPY (for invocations resulting from COPY) 536 o FLAG (for invocations resulting from flag changes) 537 Future extensions might define new events and, thus, new causes. 538 Such extensions will come with their own capability strings, and the 539 events they define will only be presented when their capabilities are 540 requested. Scripts that do not request those capabilities will not 541 see those events, and will not encounter the new cause strings. 543 4.4. New Sieve Environment Item: mailbox 545 The implementation MUST set the Environment [RFC5183] item "mailbox" 546 to the name of the mailbox that the affected message is in, in the 547 case of existing messages, or is targeted to be stored into, in the 548 case of new messages. The value of this item is fixed when the 549 script begins, and, in particular, MUST NOT change as a result of any 550 action, such as "fileinto". 552 4.5. New Sieve Environment Item: changedflags 554 If the IMAP4Flags extension [RFC5232] is available, AND the script 555 was invoked because of flag changes to an existing message, the 556 implementation MUST set the Environment [RFC5183] item "changedflags" 557 to the name(s) of the flag(s) that have changed. If the script was 558 not invoked because of flag changes, the value of this item MUST be 559 the empty string. The script will not know from this item whether 560 the flags have been set or reset, but it can use the "hasflag" test 561 to determine the current value. See example 2 in Section 5 for an 562 example of how this might be used. 564 4.6. Interaction With Sieve Tests (Comparisons) 566 Any tests against message envelope information, including the 567 "envelope" test in the Sieve base specification, as well as any such 568 test defined in extensions, are either inapplicable or have serious 569 interoperability issues when performed at other than final-delivery 570 time. Therefore, envelope tests MUST NOT be permitted in the cases 571 described here, and their use MUST generate a runtime error. 573 This extension does not affect the operation of other tests or 574 comparisons in the Sieve base specification. 576 5. Examples 578 Example 1: 579 If a new message is added to the "ActionItems" mailbox, a copy is 580 sent to the address "actionitems@example.com". 582 require ["copy", "environment", "imapsieve"]; 584 if anyof (environment :is "cause" "APPEND", 585 environment :is "cause" "COPY") { 586 if environment :is "mailbox" "ActionItems" { 587 redirect :copy "actionitems@example.com"; 588 } 589 } 591 Example 2: 592 If the script is called for any message with the \Flagged flag set 593 (tested through the IMAP4Flags extension [RFC5232]), a notification 594 is sent using the Notify extension [RFC5435]. No notification will 595 be sent, though, if we're called with an existing message that 596 already had that flag set. 598 require ["enotify", "imap4flags", "variables", 599 "environment", "imapsieve"]; 601 if environment :matches "mailbox" "*" { 602 set "mailbox" "${1}"; 603 } 605 if allof (hasflag "\\Flagged", 606 not environment :contains "changedflags" "\\Flagged") { 607 notify :message "Important message in ${mailbox}" 608 "xmpp:tim@example.com?message;subject=SIEVE"; 609 } 611 Example 3: 612 This shows an example IMAP CAPABILITY response when this extension is 613 supported. The client has done STARTTLS with the server, and is now 614 inspecting capabilities. (The untagged CAPABILITY response is split 615 here for readability only, but will be in one response message.) 617 C: A01 CAPABILITY 618 S: * CAPABILITY IMAP4rev1 AUTH=PLAIN UIDPLUS LIST-EXTENDED 619 ACL IMAPSIEVE=sieve://sieve.example.com MULTISEARCH 620 S: A01 OK done 622 6. Security Considerations 624 It is possible to introduce script processing loops by having a Sieve 625 script that is triggered by flag changes use the actions defined in 626 the IMAP4Flags extension [RFC5232]. Implementations MUST take steps 627 to prevent such loops. One way to avoid this problem is that if a 628 script is invoked by flag changes, and that script further changes 629 the flags, those flag changes SHOULD NOT trigger a Sieve script 630 invocation. 632 It is also possible to introduce loops through the "redirect" or 633 "notify" actions. See Section 10 of Sieve [RFC5228], Section 8 of 634 Sieve Notify [RFC5435], and the Security Considerations sections of 635 the applicable notification-method documents for loop-prevention 636 information. This extension does not change any of that advice. 638 Other security considerations are discussed in IMAP [RFC3501], and 639 Sieve [RFC5228], as well as in some of the other extension documents. 641 7. IANA Considerations 643 7.1. Registration of "imapsieve" IMAP capability 645 IANA is asked to add "IMAPSIEVE=" to the IMAP 4 Capabilities 646 registry, according to the IMAP 4 specification [RFC3501]. 647 (http://www.iana.org/assignments/imap4-capabilities) 649 7.2. Registration of "imapsieve" Sieve extension 651 The following information should be added to the Sieve Extensions 652 registry, according to the Sieve specification [RFC5228]. (http:// 653 www.iana.org/assignments/sieve-extensions/sieve-extensions.xml) 655 To: iana@iana.org 656 Subject: Registration of new Sieve extension 657 Capability name: imapsieve 658 Description: Add Sieve processing for IMAP events. 659 RFC number: [[this RFC]] 660 Contact address: Sieve mailing list 662 7.3. Registration of Sieve Environment Items 664 The following subsections register items in the Sieve Environment 665 Items registry, according to the Environment extension [RFC5183]. 666 (http://www.iana.org/assignments/sieve-environment-items/ sieve- 667 environment-items.xml) 669 7.3.1. Registration of Sieve Environment Item: cause 671 To: iana@iana.org 672 Subject: Registration of new Sieve environment item 673 Item name: cause 674 Description: The name of the action that caused the script to be 675 invoked. Its value is one of the following: 677 o APPEND (for invocations resulting from APPEND or MULTIAPPEND) 679 o COPY (for invocations resulting from COPY) 681 o FLAG (for invocations resulting from flag changes) 683 RFC number: [[this RFC]] 684 Contact address: Sieve mailing list 686 7.3.2. Registration of Sieve Environment Item: mailbox 688 To: iana@iana.org 689 Subject: Registration of new Sieve environment item 690 Item name: mailbox 691 Description: The name of the mailbox that the affected message is in, 692 in the case of existing messages, or is targeted to be stored into, 693 in the case of new messages. The value of this item is fixed when 694 the script begins, and, in particular, MUST NOT change as a result of 695 any action, such as "fileinto". 696 RFC number: [[this RFC]] 697 Contact address: Sieve mailing list 699 7.3.3. Registration of Sieve Environment Item: changedflags 701 To: iana@iana.org 702 Subject: Registration of new Sieve environment item 703 Item name: changedflags 704 Description: If the script was invoked because of flag changes to an 705 existing message, this contains the name(s) of the flag(s) that have 706 changed. Otherwise, the value of this item MUST be the empty string. 707 RFC number: [[this RFC]] 708 Contact address: Sieve mailing list 710 7.3.4. Registration of Sieve Environment Item: imapuser 712 To: iana@iana.org 713 Subject: Registration of new Sieve environment item 714 Item name: imapuser 715 Description: The identity (IMAP login ID) of the IMAP user that 716 caused the action. 717 RFC number: [[this RFC]] 718 Contact address: Sieve mailing list 720 7.3.5. Registration of Sieve Environment Item: imapemail 722 To: iana@iana.org 723 Subject: Registration of new Sieve environment item 724 Item name: imapemail 725 Description: The primary email address of the IMAP user that caused 726 the action (the user identified by "imapuser"). 727 RFC number: [[this RFC]] 728 Contact address: Sieve mailing list 730 7.4. Registration of IMAP METADATA Mailbox Entry Name 732 The following information should be added to the IMAP METADATA 733 Mailbox Entry Registry, according to the Metadata extension 735 [RFC5464]. 736 (http://www.iana.org/assignments/imap-metadata/imap-metadata.xml) 738 To: iana@iana.org 739 Subject: IMAP METADATA Entry Registration 740 Type: Mailbox 741 Name: /shared/imapsieve/script 742 Description: This entry name is used to define mailbox metadata 743 associated with IMAP events in Sieve for the associated mailbox. 744 Specifically, this specifies the Sieve script that will be invoked 745 when IMAP events occur on the specified mailbox. 746 Content-type: text/plain; charset=utf-8 747 RFC number: [[this RFC]] 748 Contact address: Sieve mailing list 750 7.5. Registration of IMAP METADATA Server Entry Name 752 The following information should be added to the IMAP METADATA Server 753 Entry Registry, items according to the Metadata extension [RFC5464]. 754 (http://www.iana.org/assignments/imap-metadata/imap-metadata.xml) 756 To: iana@iana.org 757 Subject: IMAP METADATA Entry Registration 758 Type: Server 759 Name: /shared/imapsieve/script 760 Description: This entry name is used to define metadata associated 761 globally with IMAP events in Sieve for the associated server. 762 Specifically, this specifies the Sieve script that will be invoked 763 when IMAP events occur on any mailbox in the server that does not 764 have its own mailbox-level /shared/imapsieve/script entry. 765 Content-type: text/plain; charset=utf-8 766 RFC number: [[this RFC]] 767 Contact address: Sieve mailing list 769 8. References 771 8.1. Normative References 773 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 774 Requirement Levels", BCP 14, RFC 2119, March 1997. 776 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 777 4rev1", RFC 3501, March 2003. 779 [RFC3502] Crispin, M., "Internet Message Access Protocol (IMAP) - 780 MULTIAPPEND Extension", RFC 3502, March 2003. 782 [RFC3894] Degener, J., "Sieve Extension: Copying Without Side 783 Effects", RFC 3894, October 2004. 785 [RFC5183] Freed, N., "Sieve Email Filtering: Environment Extension", 786 RFC 5183, May 2008. 788 [RFC5228] Guenther, P. and T. Showalter, "Sieve: An Email Filtering 789 Language", RFC 5228, January 2008. 791 [RFC5232] Melnikov, A., "Sieve Email Filtering: Imap4flags 792 Extension", RFC 5232, January 2008. 794 [RFC5464] Daboo, C., "The IMAP METADATA Extension", RFC 5464, 795 February 2009. 797 [RFC5804] Melnikov, A. and T. Martin, "A Protocol for Remotely 798 Managing Sieve Scripts", RFC 5804, July 2010. 800 [RFC6409] Gellens, R. and J. Klensin, "Message Submission for Mail", 801 STD 72, RFC 6409, November 2011. 803 8.2. Informative References 805 [RFC4315] Crispin, M., "Internet Message Access Protocol (IMAP) - 806 UIDPLUS extension", RFC 4315, December 2005. 808 [RFC5230] Showalter, T. and N. Freed, "Sieve Email Filtering: 809 Vacation Extension", RFC 5230, January 2008. 811 [RFC5235] Daboo, C., "Sieve Email Filtering: Spamtest and Virustest 812 Extensions", RFC 5235, January 2008. 814 [RFC5293] Degener, J. and P. Guenther, "Sieve Email Filtering: 815 Editheader Extension", RFC 5293, August 2008. 817 [RFC5429] Stone, A., "Sieve Email Filtering: Reject and Extended 818 Reject Extensions", RFC 5429, March 2009. 820 [RFC5435] Melnikov, A., Leiba, B., Segmuller, W., and T. Martin, 821 "Sieve Email Filtering: Extension for Notifications", 822 RFC 5435, January 2009. 824 [RFC5703] Hansen, T. and C. Daboo, "Sieve Email Filtering: MIME Part 825 Tests, Iteration, Extraction, Replacement, and Enclosure", 826 RFC 5703, October 2009. 828 Author's Address 830 Barry Leiba 831 Huawei Technologies 833 Phone: +1 646 827 0648 834 Email: barryleiba@computer.org 835 URI: http://internetmessagingtechnology.org/