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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 June 15, 2012 5 Expires: December 17, 2012 7 Support for Internet Message Access Protocol (IMAP) Events in Sieve 8 draft-ietf-sieve-imap-sieve-05 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 December 17, 2012. 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. 183 The corresponding Sieve implementation uses the Sieve capability 184 string "imapsieve", and Sieve scripts that depend upon the IMAP 185 events MUST include that string in their "required" lists. 187 Implementations that support IMAP events in Sieve MUST also support 188 IMAP Metadata [RFC5464] and Sieve Environment [RFC5183], because 189 Metadata is used to associate scripts with IMAP mailboxes and 190 Environment defines an important way for Sieve scripts to test the 191 conditions under which they have been invoked. Notwithstanding the 192 support requirement, scripts that directly use Environment MUST also 193 include its capability string in their "required" lists. 195 2.2. Existing IMAP Functions Affected by IMAP events in Sieve 197 The subsections below describe in detail the IMAP commands and 198 situations on which IMAP events in Sieve have an effect. Not all 199 Sieve actions make sense in the case of messages affected by IMAP 200 commands. See Section 3 for details. 202 It's important to note that since the base Sieve specification (see 203 [RFC5228]) and its extensions define functions for scripts that are 204 invoked during initial mail delivery, those function definitions are 205 necessarily tailored to and limited by that context. This document 206 extends those function definitions for use during IMAP events. By 207 nature of that, Sieve functions, in this extended context, may behave 208 somewhat differently, though their extended behaviour will still be 209 consistent with the functions' goals. 211 If more than one message is affected at the same time, each message 212 triggers the execution of a Sieve script separately. The scripts MAY 213 be run in parallel. 215 2.2.1. The IMAP APPEND Command 217 A message may be added to a mailbox through the IMAP APPEND command. 218 In a server that advertises "imapsieve", new messages added in this 219 way MUST trigger the execution of a Sieve script, subject to the 220 settings defined through Metadata (see Section 2.3.1). 222 2.2.2. The IMAP MULTIAPPEND Command 224 If the IMAP server supports the IMAP MultiAppend extension [RFC3502], 225 messages may be added to a mailbox through the IMAP MULTIAPPEND 226 command. In a server that advertises "imapsieve", new messages added 227 in this way MUST trigger the execution of a Sieve script, as with the 228 APPEND command, also subject to the settings defined through 229 Metadata. 231 2.2.3. The IMAP COPY Command 233 One or more messages may be added to a mailbox through the IMAP COPY 234 command. In a server that advertises "imapsieve", new messages added 235 in this way MUST trigger the execution of a Sieve script, subject to 236 the settings defined through Metadata. 238 2.2.4. Changes to IMAP Message Flags 240 One or more existing messages can have their flags changed in a 241 number of ways, including: 243 o The FETCH command (may cause the \Seen flag to be set). 245 o The STORE command (may cause the \Answered, \Deleted, \Draft, 246 \Flagged, and \Seen flags to be set or reset, and may cause 247 keywords to be set or reset). 249 o The invocation of a Sieve script on an existing message, where the 250 Sieve implementation supports the IMAP4Flags extension [RFC5232] 251 and the script uses one of the actions defined in that extension. 253 In a server that advertises "imapsieve", messages whose flags are 254 changed in any way (except as explained in the next sentence) MUST 255 trigger the execution of a Sieve script, subject to the settings 256 defined through Metadata. The exception is that in order to avoid 257 script loops, flag changes that are made as a result of a script that 258 was itself invoked because of flag changes SHOULD NOT result in 259 another script invocation. In any case, implementations MUST take 260 steps to avoid such loops. 262 For flag-change events, the Sieve script will see the message flags 263 as they are AFTER the changes. 265 2.3. New Functions Defined by IMAP events in Sieve 267 2.3.1. Interaction with Metadata 269 Support for IMAP events in Sieve requires support for IMAP Metadata 270 [RFC5464] as well, since the latter is used to associate scripts with 271 IMAP mailboxes. 273 When an applicable event occurs on an IMAP mailbox, if there is an 274 IMAP metadata entry named "/shared/imapsieve/script" for the mailbox, 275 that entry is used. If there is not, but there is an IMAP metadata 276 entry named "/shared/imapsieve/script" for the server, that entry is 277 used (providing a way to define a global script for all mailboxes on 278 a server). If neither entry exists, then no script will be invoked. 280 If a "/shared/imapsieve/script" metadata entry was selected above, 281 its value is used as the name of the Sieve script that will be 282 invoked in response to the IMAP event. If the value is empty, then 283 no script is run. 285 This specifies the mechanism for "activating" a script for a given 286 mailbox (or for all mailboxes), but does not specify a mechanism for 287 creating, storing, or validating the script. Implementations MUST 288 support ManageSieve [RFC5804], and can use the PUTSCRIPT command to 289 store the script without using the SETACTIVE command to activate it. 291 Script names used in "/shared/imapsieve/script" metadata entries are 292 the script names used on the corresponding ManageSieve server. If a 293 "/shared/imapsieve/script" metadata entry contains a script name that 294 doesn't exist in the ManageSieve server, then no Sieve script will be 295 invoked for IMAP Sieve events. 297 Only one Sieve script may currently be defined per mailbox, 298 eliminating the complexity and possible ambiguity involved with 299 coordinating the results of multiple scripts. Any sub-filtering is 300 done in the Sieve script. For example, if it's only necessary to 301 deal with flag changes, but not with new messages appended or copied, 302 the Sieve script will still be invoked for all events, and the script 303 is responsible for checking the event type. 305 The possibility is open for an extension to add support for multiple 306 scripts -- for example, per-client scripts on a multi-client user's 307 inbox, or per-user scripts on a mailbox that is shared among users. 309 Because this metadata name is associated with the mailbox, there can 310 (and it's expected that there will) be different scripts associated 311 with events for different mailboxes. Indeed, most mailboxes will 312 probably invoke no script at all. 314 3. Applicable Sieve Actions and Interactions 316 Since some Sieve actions relate specifically to the delivery of mail, 317 not all actions and extensions make sense when the messages are 318 created by other means or when changes are made to data associated 319 with existing messages. This section describes how actions in the 320 base Sieve specification, and those in extensions known at this 321 writing, relate to this specification. 323 In addition to what is specified here, interactions noted in the 324 individual specifications apply, and must be considered. 326 3.1. The Implicit Keep 328 For all cases that fall under IMAP events in Sieve, the implicit keep 329 means that the message is treated as it would have been if no Sieve 330 script were run. For APPEND, MULTIAPPEND and COPY, the message is 331 stored into the target mailbox normally. For flag changes, the 332 message is left in the mailbox. If actions have been taken that 333 change the message, those changes are considered transient and MUST 334 NOT be retained for any keep action (because IMAP messages are 335 immutable). No error is generated, but the original message, without 336 the changes, is kept. 338 3.2. The Keep Action 340 The keep action is applicable in all cases that fall under IMAP 341 events in Sieve. Its behaviour is as described for implicit keep, in 342 Section 3.1. 344 3.3. The Fileinto Action 346 If the Sieve implementation supports the fileinto action, that action 347 is applicable in all cases that fall under IMAP events in Sieve. If 348 the Copy extension [RFC3894] is available and the :copy option is 349 specified, the implicit keep is retained; otherwise, fileinto cancels 350 the implicit keep, as specified in the base Sieve specification. 352 For APPEND, MULTIAPPEND, and COPY, the message is stored into the 353 fileinto mailbox IN ADDITION TO the original target mailbox. For 354 flag changes, the message is COPIED into the fileinto mailbox, 355 without removing the original. 357 If a keep action is NOT also in effect, the original message is then 358 marked with the \Deleted flag (and a flag-change Sieve script is NOT 359 invoked). The implementation MAY then expunge the original message 360 (WITHOUT expunging other messages in the mailbox), or it MAY choose 361 to have expunges batched, or done by a user. If the server does the 362 expunge, the effect is as though a client had flagged the message and 363 done a UID EXPUNGE (see [RFC4315]) on the affected message(s) only. 364 Handling it this way allows clients to handle messages consistently, 365 and avoids hidden changes that might invalidate their message caches. 367 3.4. The Redirect Action 369 The redirect action is applicable in all cases that fall under IMAP 370 events in Sieve. It causes the message to be sent, as specified in 371 the base Sieve specification, to the designated address. If the Copy 372 extension [RFC3894] is available and the :copy option is specified, 373 the implicit keep is retained; otherwise, redirect cancels the 374 implicit keep, as specified in the base Sieve specification. 376 It's possible that a message processed in this way does not have the 377 information necessary to be redirected properly. It might lack 378 necessary header information, and there might not be appropriate 379 information for the MAIL FROM command. In such cases, the "redirect" 380 action uses Message Submission [RFC6409], and it is up to the Sieve 381 engine to supply the missing information. The redirect address is, 382 of course, used for the "RCPT TO", and the "MAIL FROM" SHOULD be set 383 to the address of the owner of the mailbox. The message submission 384 server is allowed, according to the Message Submission protocol, to 385 perform necessary fix-up to the message (see Section 8 of RFC 6409). 386 It can also reject the submission attempt, if the message is too ill- 387 formed for submission. 389 For APPEND, MULTIAPPEND, and COPY, the message is stored into the 390 target mailbox in addition to being redirected. For flag changes, 391 the message remains in its original mailbox. 393 If a keep action is NOT also in effect, the original message is then 394 marked with the \Deleted flag (and a flag-change Sieve script is NOT 395 invoked). The implementation MAY then expunge the original message 396 (WITHOUT expunging other messages in the mailbox), or it MAY choose 397 to have expunges batched, or done by a user. If the server does the 398 expunge, the effect is as though a client had flagged the message and 399 done a UID EXPUNGE (see [RFC4315]) on the affected message(s) only. 400 Handling it this way allows clients to handle messages consistently, 401 and avoids hidden changes that might invalidate their message caches. 403 3.5. The Discard Action 405 The discard action is applicable in all cases that fall under IMAP 406 events in Sieve. For APPEND, MULTIAPPEND, and COPY, the message is 407 first stored into the target mailbox. If an explicit keep action is 408 also in effect, the discard action now does nothing. Otherwise, the 409 original message is then marked with the \Deleted flag (and a flag- 410 change Sieve script is NOT invoked). The implementation MAY then 411 expunge the original message (WITHOUT expunging other messages in the 412 mailbox), or it MAY choose to have expunges batched, or done by a 413 user. If the server does the expunge, the effect is as though a 414 client had flagged the message and done a UID EXPUNGE (see [RFC4315]) 415 on the affected message(s) only. Handling it this way allows clients 416 to handle messages consistently, and avoids hidden changes that might 417 invalidate their message caches. 419 3.6. The Notify Action 421 If the Nofity extension [RFC5435] is available, the notify action is 422 applicable in all cases that fall under IMAP events in Sieve. The 423 result is that the requested notification is sent, and that the 424 message is otherwise handled as it would normally have been. 426 3.7. The Addheader and Deleteheader Actions 428 If the EditHeader extension [RFC5293] is available, it can be used to 429 make transient changes to header fields, which aren't saved in place, 430 such as for "redirect" or "fileinto" actions. Because messages in 431 IMAP mailboxes are immutable, such changes are NOT applicable for the 432 "keep" acton (explicit or implicit). See Section 3.1. 434 3.8. The Setflag, Deleteflag, and Removeflag Actions 436 Implementations of IMAP events in Sieve MUST also support the 437 IMAP4Flags extension [RFC5232], and the actions associated with it 438 are all applicable to any case that falls under IMAP events in Sieve. 440 It is worth noting also that the "hasflag" test that is defined in 441 the IMAP4Flags extension might be particularly useful in scripts 442 triggered by flag changes ("hasflag" will see the new, changed 443 flags). The flag changes behave as though a client had made the 444 change. 446 As explained above, in order to avoid script loops flag changes that 447 are made as a result of a script that was itself invoked because of 448 flag changes SHOULD NOT result in another script invocation. In any 449 case, implementations MUST take steps to avoid such loops. 451 3.9. MIME Part Tests and Replacement 453 If the MIME Part Tests extension [RFC5703] is available, all of its 454 functions can be used, but any changes made to the message, using the 455 "replace" or "enclose" action, MUST be considered transient, and are 456 only applicable with actions such as "redirect" and "fileinto". 457 Because messages in IMAP mailboxes are immutable, such changes are 458 NOT applicable for the "keep" acton (explicit or implicit). See 459 Section 3.1. 461 3.10. Spamtest and Virustest 463 If the Spamtest and Virustest extensions [RFC5235] are available, 464 they are applicable in all cases that fall under IMAP events in 465 Sieve. 467 3.11. Inapplicable Actions 469 The following actions and extensions are NOT applicable to any case 470 that falls under IMAP events in Sieve, because they are specifically 471 designed to respond to delivery of a new email message. Their 472 appearance in the "require" control or their use in an IMAP event 473 MUST result in an error condition that will terminate the Sieve 474 script: 476 reject [RFC5228] 478 ereject [RFC5429] 480 vacation [RFC5230] 482 Future extensions that are specifically designed to respond to 483 delivery of a new email message will likewise not be applicable to 484 this extension. 486 4. Interaction With Sieve Environment 488 4.1. Base Sieve Environment Items: location and phase 490 The Sieve Environment extension defines a set of standard environment 491 items (see [RFC5183], Section 4.1). Two of those items are affected 492 when the script is invoked through an IMAP event. 494 The value of "location" is set to "MS" -- evaluation is being 495 performed by a Message Store. 497 The value of "phase" is set to "post" -- processing is taking place 498 after (or perhaps instead of, in the case of APPEND) final delivery. 500 4.2. New Sieve Environment Items: imapuser and imapemail 502 In the normal case, when Sieve is used in final delivery, there is no 503 identity for the "filer" -- the user who is creating or changing the 504 message. In this case, there is such an identity, and a Sieve script 505 might want to access that identity. 507 Implementations MUST set and make available two new environment 508 items: 510 "imapuser" -- the identity (login ID) of the IMAP user that caused 511 the action. This MUST be the empty string if it is accessed during 512 normal (final delivery) Sieve processing. 514 "imapemail" -- the primary email address of the IMAP user that caused 515 the action (the user identified by "imapuser"). In some 516 implementations, "imapuser" and "imapemail" might have the same 517 value. This MUST be the empty string if it is accessed during normal 518 (final delivery) Sieve processing. 520 4.3. New Sieve Environment Item: cause 522 Each mailbox uses a single script for all the change conditions 523 described in this document (append, copy, flag changes). To support 524 that, the implementation MUST set the Environment [RFC5183] item 525 "cause", which contains the name of the action that caused the script 526 to be invoked. Its value is one of the following: 528 o APPEND (for invocations resulting from APPEND or MULTIAPPEND) 530 o COPY (for invocations resulting from COPY) 532 o FLAG (for invocations resulting from flag changes) 533 Future extensions might define new events and, thus, new causes. 534 Such extensions will come with their own capability strings, and the 535 events they define will only be presented when their capabilities are 536 requested. Scripts that do not request those capabilities will not 537 see those events, and will not encounter the new cause strings. 539 4.4. New Sieve Environment Item: mailbox 541 The implementation MUST set the Environment [RFC5183] item "mailbox" 542 to the name of the mailbox that the affected message is in, in the 543 case of existing messages, or is targeted to be stored into, in the 544 case of new messages. The value of this item is fixed when the 545 script begins, and, in particular, MUST NOT change as a result of any 546 action, such as "fileinto". 548 4.5. New Sieve Environment Item: changedflags 550 If the IMAP4Flags extension [RFC5232] is available, AND the script 551 was invoked because of flag changes to an existing message, the 552 implementation MUST set the Environment [RFC5183] item "changedflags" 553 to the name(s) of the flag(s) that have changed. If the script was 554 not invoked because of flag changes, the value of this item MUST be 555 the empty string. The script will not know from this item whether 556 the flags have been set or reset, but it can use the "hasflag" test 557 to determine the current value. See example 2 in Section 5 for an 558 example of how this might be used. 560 4.6. Interaction With Sieve Tests (Comparisons) 562 Any tests against message envelope information, including the 563 "envelope" test in the Sieve base specification, as well as any such 564 test defined in extensions, are either inapplicable or have serious 565 interoperability issues when performed at other than final-delivery 566 time. Therefore, envelope tests MUST NOT be permitted in the cases 567 described here, and their use MUST generate a runtime error. 569 This extension does not affect the operation of other tests or 570 comparisons in the Sieve base specification. 572 5. Examples 574 Example 1: 575 If a new message is added to the "ActionItems" mailbox, a copy is 576 sent to the address "actionitems@example.com". 578 require ["copy", "environment", "imapsieve"]; 580 if anyof (environment :is "cause" "APPEND", 581 environment :is "cause" "COPY") { 582 if environment :is "mailbox" "ActionItems" { 583 redirect :copy "actionitems@example.com"; 584 } 585 } 587 Example 2: 588 If the script is called for any message with the \Flagged flag set 589 (tested through the IMAP4Flags extension [RFC5232]), a notification 590 is sent using the Notify extension [RFC5435]. No notification will 591 be sent, though, if we're called with an existing message that 592 already had that flag set. 594 require ["enotify", "imap4flags", "variables", 595 "environment", "imapsieve"]; 597 if environment :matches "mailbox" "*" { 598 set "mailbox" "${1}"; 599 } 601 if allof (hasflag "\\Flagged", 602 not environment :contains "changedflags" "\\Flagged") { 603 notify :message "Important message in ${mailbox}" 604 "xmpp:tim@example.com?message;subject=SIEVE"; 605 } 607 Example 3: 608 This shows an example IMAP CAPABILITY response when this extension is 609 supported. The client has done STARTTLS with the server, and is now 610 inspecting capabilities. (The untagged CAPABILITY response is split 611 here for readability only, but will be in one response message.) 613 C: A01 CAPABILITY 614 S: * CAPABILITY IMAP4rev1 AUTH=PLAIN UIDPLUS LIST-EXTENDED 615 ACL IMAPSIEVE=sieve://sieve.example.com MULTISEARCH 616 S: A01 OK done 618 6. Security Considerations 620 It is possible to introduce script processing loops by having a Sieve 621 script that is triggered by flag changes use the actions defined in 622 the IMAP4Flags extension [RFC5232]. Implementations MUST take steps 623 to prevent such loops. One way to avoid this problem is that if a 624 script is invoked by flag changes, and that script further changes 625 the flags, those flag changes SHOULD NOT trigger a Sieve script 626 invocation. 628 It is also possible to introduce loops through the "redirect" or 629 "notify" actions. See Section 10 of Sieve [RFC5228], Section 8 of 630 Sieve Notify [RFC5435], and the Security Considerations sections of 631 the applicable notification-method documents for loop-prevention 632 information. This extension does not change any of that advice. 634 Other security considerations are discussed in IMAP [RFC3501], and 635 Sieve [RFC5228], as well as in some of the other extension documents. 637 7. IANA Considerations 639 7.1. Registration of "imapsieve" IMAP capability 641 IANA is asked to add "IMAPSIEVE=" to the IMAP 4 Capabilities 642 registry, according to the IMAP 4 specification [RFC3501]. 643 (http://www.iana.org/assignments/imap4-capabilities) 645 7.2. Registration of "imapsieve" Sieve extension 647 The following information should be added to the Sieve Extensions 648 registry, according to the Sieve specification [RFC5228]. (http:// 649 www.iana.org/assignments/sieve-extensions/sieve-extensions.xml) 651 To: iana@iana.org 652 Subject: Registration of new Sieve extension 653 Capability name: imapsieve 654 Description: Add Sieve processing for IMAP events. 655 RFC number: [[this RFC]] 656 Contact address: Sieve mailing list 658 7.3. Registration of Sieve Environment Items 660 The following subsections register items in the Sieve Environment 661 Items registry, according to the Environment extension [RFC5183]. 662 (http://www.iana.org/assignments/sieve-environment-items/ sieve- 663 environment-items.xml) 665 7.3.1. Registration of Sieve Environment Item: cause 667 To: iana@iana.org 668 Subject: Registration of new Sieve environment item 669 Item name: cause 670 Description: The name of the action that caused the script to be 671 invoked. Its value is one of the following: 673 o APPEND (for invocations resulting from APPEND or MULTIAPPEND) 675 o COPY (for invocations resulting from COPY) 677 o FLAG (for invocations resulting from flag changes) 679 RFC number: [[this RFC]] 680 Contact address: Sieve mailing list 682 7.3.2. Registration of Sieve Environment Item: mailbox 684 To: iana@iana.org 685 Subject: Registration of new Sieve environment item 686 Item name: mailbox 687 Description: The name of the mailbox that the affected message is in, 688 in the case of existing messages, or is targeted to be stored into, 689 in the case of new messages. The value of this item is fixed when 690 the script begins, and, in particular, MUST NOT change as a result of 691 any action, such as "fileinto". 692 RFC number: [[this RFC]] 693 Contact address: Sieve mailing list 695 7.3.3. Registration of Sieve Environment Item: changedflags 697 To: iana@iana.org 698 Subject: Registration of new Sieve environment item 699 Item name: changedflags 700 Description: If the script was invoked because of flag changes to an 701 existing message, this contains the name(s) of the flag(s) that have 702 changed. Otherwise, the value of this item MUST be the empty string. 703 RFC number: [[this RFC]] 704 Contact address: Sieve mailing list 706 7.3.4. Registration of Sieve Environment Item: imapuser 708 To: iana@iana.org 709 Subject: Registration of new Sieve environment item 710 Item name: imapuser 711 Description: The identity (IMAP login ID) of the IMAP user that 712 caused the action. 713 RFC number: [[this RFC]] 714 Contact address: Sieve mailing list 716 7.3.5. Registration of Sieve Environment Item: imapemail 718 To: iana@iana.org 719 Subject: Registration of new Sieve environment item 720 Item name: imapemail 721 Description: The primary email address of the IMAP user that caused 722 the action (the user identified by "imapuser"). 723 RFC number: [[this RFC]] 724 Contact address: Sieve mailing list 726 7.4. Registration of IMAP METADATA Mailbox Entry Name 728 The following information should be added to the IMAP METADATA 729 Mailbox Entry Registry, according to the Metadata extension 731 [RFC5464]. 732 (http://www.iana.org/assignments/imap-metadata/imap-metadata.xml) 734 To: iana@iana.org 735 Subject: IMAP METADATA Entry Registration 736 Type: Mailbox 737 Name: /shared/imapsieve/script 738 Description: This entry name is used to define mailbox metadata 739 associated with IMAP events in Sieve for the associated mailbox. 740 Specifically, this specifies the Sieve script that will be invoked 741 when IMAP events occur on the specified mailbox. 742 Content-type: text/plain; charset=utf-8 743 RFC number: [[this RFC]] 744 Contact address: Sieve mailing list 746 7.5. Registration of IMAP METADATA Server Entry Name 748 The following information should be added to the IMAP METADATA Server 749 Entry Registry, items according to the Metadata extension [RFC5464]. 750 (http://www.iana.org/assignments/imap-metadata/imap-metadata.xml) 752 To: iana@iana.org 753 Subject: IMAP METADATA Entry Registration 754 Type: Server 755 Name: /shared/imapsieve/script 756 Description: This entry name is used to define metadata associated 757 globally with IMAP events in Sieve for the associated server. 758 Specifically, this specifies the Sieve script that will be invoked 759 when IMAP events occur on any mailbox in the server that does not 760 have its own mailbox-level /shared/imapsieve/script entry. 761 Content-type: text/plain; charset=utf-8 762 RFC number: [[this RFC]] 763 Contact address: Sieve mailing list 765 8. References 767 8.1. Normative References 769 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 770 Requirement Levels", BCP 14, RFC 2119, March 1997. 772 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 773 4rev1", RFC 3501, March 2003. 775 [RFC3502] Crispin, M., "Internet Message Access Protocol (IMAP) - 776 MULTIAPPEND Extension", RFC 3502, March 2003. 778 [RFC3894] Degener, J., "Sieve Extension: Copying Without Side 779 Effects", RFC 3894, October 2004. 781 [RFC5183] Freed, N., "Sieve Email Filtering: Environment Extension", 782 RFC 5183, May 2008. 784 [RFC5228] Guenther, P. and T. Showalter, "Sieve: An Email Filtering 785 Language", RFC 5228, January 2008. 787 [RFC5232] Melnikov, A., "Sieve Email Filtering: Imap4flags 788 Extension", RFC 5232, January 2008. 790 [RFC5464] Daboo, C., "The IMAP METADATA Extension", RFC 5464, 791 February 2009. 793 [RFC5804] Melnikov, A. and T. Martin, "A Protocol for Remotely 794 Managing Sieve Scripts", RFC 5804, July 2010. 796 [RFC6409] Gellens, R. and J. Klensin, "Message Submission for Mail", 797 STD 72, RFC 6409, November 2011. 799 8.2. Informative References 801 [RFC4315] Crispin, M., "Internet Message Access Protocol (IMAP) - 802 UIDPLUS extension", RFC 4315, December 2005. 804 [RFC5230] Showalter, T. and N. Freed, "Sieve Email Filtering: 805 Vacation Extension", RFC 5230, January 2008. 807 [RFC5235] Daboo, C., "Sieve Email Filtering: Spamtest and Virustest 808 Extensions", RFC 5235, January 2008. 810 [RFC5293] Degener, J. and P. Guenther, "Sieve Email Filtering: 811 Editheader Extension", RFC 5293, August 2008. 813 [RFC5429] Stone, A., "Sieve Email Filtering: Reject and Extended 814 Reject Extensions", RFC 5429, March 2009. 816 [RFC5435] Melnikov, A., Leiba, B., Segmuller, W., and T. Martin, 817 "Sieve Email Filtering: Extension for Notifications", 818 RFC 5435, January 2009. 820 [RFC5703] Hansen, T. and C. Daboo, "Sieve Email Filtering: MIME Part 821 Tests, Iteration, Extraction, Replacement, and Enclosure", 822 RFC 5703, October 2009. 824 Author's Address 826 Barry Leiba 827 Huawei Technologies 829 Phone: +1 646 827 0648 830 Email: barryleiba@computer.org 831 URI: http://internetmessagingtechnology.org/