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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 2234 (ref. 'ABNF') (Obsoleted by RFC 4234) ** Obsolete normative reference: RFC 3348 (ref. 'CMbox') (Obsoleted by RFC 5258) ** Obsolete normative reference: RFC 3501 (ref. 'IMAP4') (Obsoleted by RFC 9051) Summary: 6 errors (**), 0 flaws (~~), 3 warnings (==), 8 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IMAP Extensions Working Group B. Leiba 3 Internet-Draft IBM T.J. Watson Research Center 4 Updates: 2193 (if approved) A. Melnikov 5 Obsoletes: 3348 (if approved) Isode Limited 6 Expires: November 17, 2005 May 16, 2005 8 IMAP4 LIST Command Extensions 9 draft-ietf-imapext-list-extensions-13 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on November 17, 2005. 36 Copyright Notice 38 Copyright (C) The Internet Society (2005). 40 Abstract 42 IMAP4 has two commands for listing mailboxes: LIST and LSUB. As we 43 have added extensions, such as Mailbox Referrals, that have required 44 specialized lists we have had to expand the number of list commands, 45 since each extension must add its function to both LIST and LSUB, and 46 these commands are not, as they are defined, extensible. If we've 47 needed the extensions to work together, we've had to add a set of 48 commands to mix the different options, the set increasing in size 49 with each new extension. This document describes an extension to the 50 base LIST command that will allow these additions to be done with 51 mutually compatible options to the LIST command, avoiding the 52 exponential increase in specialized list commands. 54 Note 56 A revised version of this draft document will be submitted to the RFC 57 editor as an Proposed Standard for the Internet Community. 58 Discussion and suggestions for improvement are requested, and should 59 be sent to ietf-imapext@imc.org. 61 This document obsoletes RFC 3348 and updates RFC 2193. 63 Table of Contents 65 1. Conventions used in this document . . . . . . . . . . . . . . 3 67 2. Introduction and overview . . . . . . . . . . . . . . . . . . 4 69 3. Extended LIST Command . . . . . . . . . . . . . . . . . . . . 6 70 3.1 General principles for returning LIST responses . . . . . . . 10 71 3.2 Additional requirements on LIST-EXTENDED clients . . . . . . . 11 72 3.3 CHILDINFO extended data item . . . . . . . . . . . . . . . . . 11 74 4. The CHILDREN return Option . . . . . . . . . . . . . . . . . . 14 76 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 78 6. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 26 80 7. Security Considerations . . . . . . . . . . . . . . . . . . . 29 82 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 83 8.1 Guidelines for IANA . . . . . . . . . . . . . . . . . . . . . 30 84 8.2 Registration procedure and Change control . . . . . . . . . . 30 85 8.3 Registration template for LIST-EXTENDED options . . . . . . . 31 86 8.4 Initial LIST-EXTENDED option registrations . . . . . . . . . . 32 87 8.5 Registration template for LIST-EXTENDED extended data item . . 34 88 8.6 Initial LIST-EXTENDED extended data item registrations . . . . 35 90 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 36 92 10. Normative References . . . . . . . . . . . . . . . . . . . . . 36 94 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 36 96 Intellectual Property and Copyright Statements . . . . . . . . 38 98 1. Conventions used in this document 100 In examples, "C:" indicates lines sent by a client that is connected 101 to a server. "S:" indicates lines sent by the server to the client. 103 The words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" are 104 used in this document as specified in RFC 2119 [Kwds]. 106 The term "canonical LIST pattern" refers to the canonical pattern 107 constructed internally by the server from the reference and mailbox 108 name arguments (Section 6.3.8 of [IMAP4]). The [IMAP4] LIST command 109 returns only mailboxes that match the canonical LIST pattern. 111 Other terms are introduced where they are referenced for the first 112 time. 114 2. Introduction and overview 116 The LIST command is extended by amending the syntax to allow options 117 and multiple patterns to be specified. The list of options replaces 118 the several commands that are currently used to mix and match the 119 information requested. The new syntax is backward- compatible, with 120 no ambiguity: the new syntax is being used if one of the following 121 conditions is true: 123 1. if the first word after the command name begins with a 124 parenthesis ("LIST selection options"); 126 2. if the second word after the command name begins with a 127 parenthesis ("multiple mailbox patterns"); 129 3. if the LIST command has more than 2 parameters ("LIST return 130 options"); 132 Otherwise the original syntax is used. 134 By adding options to the LIST command, we are announcing the intent 135 to phase out and eventually to deprecate the RLIST and RLSUB commands 136 described in [MBRef]. We are also defining the mechanism to request 137 extended mailbox information, such as is described in the "Child 138 Mailbox Extension" [CMbox]. The base LSUB command is not deprecated 139 by this extension; rather, this extension adds a way to obtain 140 subscription information with more options, with those server 141 implementations that support it. Clients that simply need a list of 142 subscribed mailboxes, as provided by the LSUB command, SHOULD 143 continue to use that command. 145 This document defines an IMAP4 extension that is identified by the 146 capability string "LIST-EXTENDED". The LIST-EXTENDED extension makes 147 the following changes to the IMAP4 protocol, which are described in 148 more detail in Section 3 and Section 4: 150 a. defines new syntax for LIST command options. 152 b. extends LIST to allow for multiple mailbox patterns. 154 c. adds LIST command selection options: SUBSCRIBED, REMOTE and 155 RECURSIVEMATCH. 157 d. adds LIST command return options: SUBSCRIBED and CHILDREN. 159 e. adds new mailbox attributes: "\NonExistent", "\Subscribed", 160 "\Remote", "\HasChildren" and "\HasNoChildren". 162 f. adds CHILDINFO extended data item. 164 3. Extended LIST Command 166 This extension updates the syntax of the LIST command to allow for 167 multiple mailbox patterns to be specified, if they are enclosed in 168 parantheses. A mailbox name match a list of mailbox patterns if it 169 matches at least one mailbox pattern. Note that if a mailbox name 170 matches multiple mailbox patterns from the list, the server should 171 return only a single LIST response. 173 Note that the non-extended LIST command is required to treat an empty 174 ("" string) mailbox name argument as a special request to return the 175 hierarchy delimiter and the root name of the name given in the 176 reference parameter (as per [IMAP4]). However ANY extended LIST 177 command (extended in any of 3 ways specified in Section 2, or any 178 combination of therof) MUST NOT treat the empty mailbox name as such 179 special request and any regular processing described in this document 180 applies. In particular, if an extended LIST command has multiple 181 mailbox names and one (or more) of them is the empty string, the 182 empty string MUST be ignored for the purpose of matching. 184 Some servers might restrict which patterns are allowed in a LIST 185 command. If a server doesn't accept a particular pattern, it MUST 186 silently ignore it. 188 The LIST command syntax is also extended in two additional ways: by 189 adding a parenthesized list of command options between the command 190 name and the reference name (LIST selection options) and an optional 191 list of options at the end that control what kind of information 192 should be returned (LIST return options). See the formal syntax in 193 Section 6 for specific details. 195 A LIST selection option tells the server which mailbox names should 196 be selected by the LIST operation. The server should return 197 information about all mailbox names that match any of the "canonical 198 LIST pattern" (as described above) and satisfy additional selection 199 criteria (if any) specified by the LIST selection options. Let's 200 call any such mailbox name a "matched mailbox name". When multiple 201 selection options are specified, the server MUST return information 202 about mailbox names that satisfy every selection option, unless a 203 description of a particular specified option prescribes special 204 rules. An example of an option prescribing special rules is the 205 RECURSIVEMATCH selection option described later in this section. We 206 will use the term "selection criteria" when referring collectively to 207 all selection options specified in a LIST command. 209 A LIST return option controls which information is returned for each 210 matched mailbox name. Note that return options MUST NOT cause the 211 server to report information about additional mailbox names. If the 212 client has not specified any return option, only information about 213 attributes should be returned by the server. (Of course the server 214 is allowed to include any other information at will.) 216 Both selection and return command options will be defined in this 217 document and in approved extension documents; each option will be 218 enabled by a capability string (one capability may enable multiple 219 options), and a client MUST NOT send an option for which the server 220 has not advertised support. A server MUST respond to options it does 221 not recognize with a BAD response. The client SHOULD NOT specify any 222 option more than once, however if the client does this, the server 223 MUST act as if it received the option only once. The order in which 224 options are specified by the client is not significant. 226 In general, each selection option except for RECURSIVEMATCH will have 227 a corresponding return option. The REMOTE selection option is an 228 anomaly in this regard, and does not have a corresponding return 229 option. That is because it expands, rather than restricts, the set 230 of mailboxes that are returned. Future extensions to this 231 specification should keep parallelism in mind, and define a pair of 232 corresponding options. 234 This extension is identified by the capability string "LIST- 235 EXTENDED", and support for it is a prerequisite for any future 236 extensions that require specialized forms of the LIST command. Such 237 extensions MUST refer to this document and MUST add their function 238 through command options as described herein. Note that extensions 239 that don't require support for an extended LIST command, but use 240 extended LIST responses (see below), don't need to advertise the 241 "LIST-EXTENDED" capability string. 243 This extension also defines extensions to the LIST response, allowing 244 a series of extended fields at the end, a parenthesized list of 245 tagged data (also referred to as "extended data item"). The first 246 element of an extended field is a tag, which identifies type of the 247 data. Tags MUST be registered with IANA, as described in Section 8.5 248 of this document. An example of such extended set might be 250 ((tablecloth (("fringe" "lacy")("color" "white")))(X-Sample 251 "text")) 253 or... 255 ((tablecloth ("fringe" "lacy"))(X-Sample "text" "and even more 256 text")) 258 See the formal grammar, below, for the full syntactic details. The 259 server MUST NOT return any extended data item, unless the client has 260 expressed its ability to support extended LIST responses, for example 261 by using an extended LIST command. The server MAY return data in the 262 extended fields that was not solicited by the client. The client 263 MUST ignore all extended fields it doesn't recognize. 265 The LIST-EXTENDED capability also defines several new mailbox 266 attributes. 268 The "\NonExistent" attribute indicates that a mailbox does not 269 actually exist. Note that this attribute is not meaningful by 270 itself, as mailboxes that match the canonical LIST pattern but don't 271 exist must not be returned unless one of the two conditions listed 272 below is also satisfied: 274 a. the mailbox also satisfies the selection criteria (for example, 275 its name is subscribed and the "SUBSCRIBED" selection option has 276 been specified) 278 b. "RECURSIVEMATCH" has been specified, and the mailbox has at least 279 one child mailbox that matches the LIST pattern and selection 280 criteria. 282 In practice this means that the "\NonExistent" attribute is usually 283 returned with one or more of "\Subscribed", "\Remote" or the 284 CHILDINFO extended data item (see their description below). 286 The "\NonExistent" attribute implies "\NoSelect". The "\NonExistent" 287 attribute MUST be supported and MUST be accurately computed. 289 The selection options defined in this specification are 291 SUBSCRIBED - causes the LIST command to list subscribed names, rather 292 than the existing mailboxes. This will often be a subset of the 293 actual mailboxes. It's also possible for this list to contain the 294 names of mailboxes that don't exist. In any case, the list MUST 295 include exactly those mailbox names that match the canonical list 296 pattern and are subscribed to. This option is intended to 297 supplement the LSUB command. Of particular note are the mailbox 298 attributes as returned by this option, compared with what is 299 returned by LSUB. With the latter, the attributes returned may 300 not reflect the actual attribute status on the mailbox name, and 301 the \NoSelect attribute has a special meaning (it indicates that 302 this mailbox is not, itself, subscribed, but that it has child 303 mailboxes that are). With the SUBSCRIBED selection option 304 described here, the attributes are accurate, complete, and have no 305 special meanings. "LSUB" and "LIST (SUBSCRIBED)" are, thus, not 306 the same thing, and some servers must do significant extra work to 307 respond to "LIST (SUBSCRIBED)". Because of this, clients SHOULD 308 continue to use "LSUB" unless they specifically want the 309 additional information offered by "LIST (SUBSCRIBED)". 311 This option defines a new mailbox attribute, "\Subscribed", that 312 indicates that a mailbox name is subscribed to. The "\Subscribed" 313 attribute MUST be supported and MUST be accurately computed when 314 the SUBSCRIBED selection option is specified. 316 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 317 return option (see below). 319 REMOTE - causes the LIST command to show remote mailboxes as well as 320 local ones, as described in [MBRef]. This option is intended to 321 replace the RLIST command and, in conjunction with the SUBSCRIBED 322 selection option, the RLSUB command. 324 This option defines a new mailbox attribute, "\Remote", that 325 indicates that a mailbox is a remote mailbox. The "\Remote" 326 attribute MUST be accurately computed when the REMOTE option is 327 specified. 329 Note that a server implementation that doesn't support any remote 330 mailboxes is compliant with this specification as long as it 331 accepts and ignores the REMOTE selection option. Note that if the 332 server choses to ignore the REMOTE selection option, it still has 333 to treat RECURSIVEMATCH REMOTE as a valid combination of selection 334 options (see also the description of the RECURSIVEMATCH option 335 below). 337 RECURSIVEMATCH - this option forces the server to return information 338 about parent mailboxes that don't match other selection options, 339 but have some submailboxes that do. Information about children is 340 returned in the CHILDINFO extended data item, as described in 341 Section 3.3. 343 Note 1: In order for a parent mailbox to be returned, it still has 344 to match the canonical LIST pattern. 346 Note 2: When returning the CHILDINFO extended data item, it 347 doesn't matter if the submailbox matches the canonical LIST 348 pattern or not. See also example 9 in Section 5. 350 The RECURSIVEMATCH option MUST NOT occur as the only selection 351 option, as it only makes sense when other selection options are 352 also used. The server MUST return BAD tagged response in such 353 case. 355 Note that even if RECURSIVEMATCH option is specified, the client 356 MUST still be able to handle a case when a CHILDINFO extended data 357 item is returned and there are no submailboxes that meet the 358 selection criteria of the given LIST command, as they can be 359 deleted/renamed after the LIST response was sent, but before the 360 client had a chance to access them. 362 The return options defined in this specification are 364 SUBSCRIBED - causes the LIST command to return subscription state for 365 all matching mailbox names. The "\Subscribed" attribute MUST be 366 supported and MUST be accurately computed when the SUBSCRIBED 367 return option is specified. Further, all mailbox flags MUST be 368 accurately computed (this differs from the behaviour of the LSUB 369 command). 371 CHILDREN - Requests mailbox child information as originally proposed 372 in [CMbox]. See Section 4, below, for details. This option MUST 373 be supported by all servers. 375 3.1 General principles for returning LIST responses 377 This section outlines several principles that can be used by server 378 implementations of this document to decide if a LIST response should 379 be returned, as well as how many responses and what kind of 380 information they may contain. 382 1. Exactly one LIST response should be returned for each mailbox 383 name which matches the canonical LIST pattern. Server 384 implementors must not assume that clients will be able to 385 assemble mailbox attributes and other information returned in 386 multiple LIST responses. 388 2. There are only two reasons for including a matching mailbox name 389 in the responses to the LIST command (Note that the server is 390 allowed to return unsolicited responses at any time. Such 391 responses are not governed by this rule): 393 A. the mailbox name also satisfies the selection criteria; 394 B. the mailbox name doesn't satisfy the selection criteria, but 395 it has at least one child mailbox name that satisfies the 396 selection criteria and that doesn't match the canonical LIST 397 pattern. 398 For more information on this case see the CHILDINFO extended 399 data item described in Section 3.3. Note that the CHILDINFO 400 extended data item can only be returned when the 401 RECURSIVEMATCH selection option is specified. 403 3. Attributes returned in the same LIST response must be treated 404 additively. For example the following response 406 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 408 means that the "Fruit/Peach" mailbox doesn't exist, but it is 409 subscribed. 411 3.2 Additional requirements on LIST-EXTENDED clients 413 All clients that support this extension MUST treat an attribute with 414 a stronger meaning, as implying any attribute that can be inferred 415 from it. For example, the client must treat presence of the 416 \NoInferiors attribute as if the \HasNoChildren attribute was also 417 sent by the server. 419 The following table summarizes inference rules described in 420 Section 3. 422 +--------------------+-------------------+ 423 | returned attribute | implied attribute | 424 +--------------------+-------------------+ 425 | \NoInferiors | \HasNoChildren | 426 | | | 427 | \NonExistent | \NoSelect | 428 +--------------------+-------------------+ 430 3.3 CHILDINFO extended data item 432 The CHILDINFO extended data item MUST only be returned when the 433 client has specified the RECURSIVEMATCH selection option. 435 The CHILDINFO extended data item in a LIST response describes the 436 selection criteria that has caused it to be returned and indicates 437 that the mailbox has st least one child mailbox that matches the 438 selection criteria. 440 The LSUB command indicates this condition by using the "\NoSelect" 441 attribute, but the LIST (SUBSCRIBED) command MUST NOT do that, since 442 "\NoSelect" retains its original meaning here. Further, the 443 CHILDINFO extended data item is more general, in that it can be used 444 with any extended set of selection criteria. 446 The returned selection criteria allow the client to distinguish a 447 solicited response from an unsolicited one, as well as to distinguish 448 among solicited responses caused by multiple pipelined LIST commands 449 that specify different criteria. 451 Servers SHOULD ONLY return a non-matching mailbox name along with 452 CHILDINFO if at least one matching child is not also being returned. 453 That is, servers SHOULD suppress redundant CHILDINFO responses. 455 Examples 8 and 10 in Section 5 demonstrate the difference between 456 present CHILDINFO extended data item and the "\HasChildren" 457 attribute. 459 The following table summarizes interaction between the "\NonExistent" 460 attribute and CHILDINFO (the first collumn describes if the parent 461 mailbox exists): 463 +----------------+----------------+----------------+----------------+ 464 | exists | meets the | has a child | returned | 465 | | selection | that meets the | LIST-EXTENDED | 466 | | criteria | selection | attributes and | 467 | | | criteria | CHILDINFO | 468 +----------------+----------------+----------------+----------------+ 469 | no | no | no | no LIST | 470 | | | | response | 471 | | | | returned | 472 | | | | | 473 | yes | no | no | no LIST | 474 | | | | response | 475 | | | | returned | 476 | | | | | 477 | no | yes | no | (\NonExistent | 478 | | | | ) | 479 | | | | | 480 | yes | yes | no | () | 481 | | | | | 482 | no | no | yes | (\NonExistent) | 483 | | | | + CHILDINFO | 484 | | | | | 485 | yes | no | yes | () + CHILDINFO | 486 | | | | | 487 | no | yes | yes | (\NonExistent | 488 | | | | ) + | 489 | | | | CHILDINFO | 490 | | | | | 491 | yes | yes | yes | () + | 492 | | | | CHILDINFO | 493 +----------------+----------------+----------------+----------------+ 495 where is one or more attributes that correspond to the 496 selection criteria, for example for the SUBSCRIBED option the 497 is \Subscribed. 499 4. The CHILDREN return Option 501 The CHILDREN return option implements the Child Mailbox Extension, 502 originally proposed by Mike Gahrns and Raymond Cheng, of Microsoft 503 Corporation. Most of the information in this section is taken 504 directly from their original specification [CMbox]. The CHILDREN 505 return option is simply an indication that the client wants this 506 information; a server MAY provide it even if the option is not 507 specified. 509 Many IMAP4 [IMAP4] clients present to the user a hierarchical view of 510 the mailboxes that a user has access to. Rather than initially 511 presenting to the user the entire mailbox hierarchy, it is often 512 preferable to show to the user a collapsed outline list of the 513 mailbox hierarchy (particularly if there is a large number of 514 mailboxes). The user can then expand the collapsed outline hierarchy 515 as needed. It is common to include within the collapsed hierarchy a 516 visual clue (such as a ''+'') to indicate that there are child 517 mailboxes under a particular mailbox. When the visual clue is 518 clicked the hierarchy list is expanded to show the child mailboxes. 519 The CHILDREN return option provides a mechanism for a client to 520 efficiently determine if a particular mailbox has children, without 521 issuing a LIST "" * or a LIST "" % for each mailbox name. The 522 CHILDREN return option defines two new attributes that MAY be 523 returned within a LIST response: \HasChildren and \HasNoChildren. 524 While these attributes MAY be returned in response to any LIST 525 command, the CHILDREN return option is provided to indicate that the 526 client particularly wants this information. If the CHILDREN return 527 option is present, the server MUST return these attributes even if 528 their computation is expensive. 530 \HasChildren 532 The presence of this attribute indicates that the mailbox has 533 child mailboxes. A server SHOULD NOT set this attribute if 534 there are child mailboxes, and the user does not have 535 permissions to access any of them. In this case, \HasNoChildren 536 SHOULD be used. In many cases, however, a server may not be 537 able to efficiently compute whether a user has access to all 538 child mailboxes. As such a client MUST be prepared to accept 539 the \HasChildren attribute as a hint. That is, a mailbox MAY be 540 flagged with the \HasChildren attribute, but no child mailboxes 541 will appear in the LIST response. 543 \HasNoChildren 544 The presence of this attribute indicates that the mailbox has NO 545 child mailboxes that are accessible to the currently 546 authenticated user. 548 In some instances a server that supports the LIST-EXTENDED extension 549 might not be able to determine whether a mailbox has children. For 550 example it may have difficulty determining whether there are child 551 mailboxes when LISTing mailboxes while operating in a particular 552 namespace. In these cases, a server MAY exclude both the 553 \HasChildren and \HasNoChildren attributes in the LIST response. As 554 such, a client can not make any assumptions about whether a mailbox 555 has children based upon the absence of a single attribute. In 556 particular, some servers may not be able to combine the SUBSCRIBED 557 selection option and CHILDREN return option. Such servers MUST 558 honour the SUBSCRIBED selection option, and they will simply ignore 559 the CHILDREN return option if both are requested. It is an error for 560 the server to return both a \HasChildren and a \HasNoChildren 561 attribute in a LIST response. 563 Note: the \HasNoChildren attribute should not be confused with the 564 IMAP4 [IMAP4] defined attribute \NoInferiors which indicates that no 565 child mailboxes exist now and none can be created in the future. 567 5. Examples 569 1: The first example shows the complete local hierarchy that will be 570 used for the other examples. 572 C: A01 LIST "" "*" 574 S: * LIST (\Marked \NoInferiors) "/" "inbox" 576 S: * LIST () "/" "Fruit" 578 S: * LIST () "/" "Fruit/Apple" 580 S: * LIST () "/" "Fruit/Banana" 582 S: * LIST () "/" "Tofu" 584 S: * LIST () "/" "Vegetable" 586 S: * LIST () "/" "Vegetable/Broccoli" 588 S: * LIST () "/" "Vegetable/Corn" 590 S: A01 OK done 592 2: In the next example, we'll see the subscribed mailboxes. This is 593 similar to, but not equivalent with, . Note that 594 the mailbox called "Fruit/Peach" is subscribed to, but does not 595 actually exist (perhaps it was deleted while still subscribed). 596 The "Fruit" mailbox is not subscribed to, but it has two 597 subscribed children. The "Vegetable" mailbox is subscribed and 598 has two children, one of them is subscribed as well. 600 C: A02 LIST (SUBSCRIBED) "" "*" 602 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 604 S: * LIST (\Subscribed) "/" "Fruit/Banana" 606 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 608 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 609 S: A02 OK done 611 3: The next example shows the use of the CHILDREN option. The 612 client, without having to list the second level of hierarchy, now 613 knows which of the top-level mailboxes have submailboxes 614 (children) and which do not. Note that it's not necessary for 615 the server to return the \HasNoChildren attribute for the inbox, 616 because the \NoInferiors attribute already implies that, and has 617 a stronger meaning. 619 C: A03 LIST () "" "%" RETURN (CHILDREN) 621 S: * LIST (\Marked \NoInferiors) "/" "inbox" 623 S: * LIST (\HasChildren) "/" "Fruit" 625 S: * LIST (\HasNoChildren) "/" "Tofu" 627 S: * LIST (\HasChildren) "/" "Vegetable" 629 S: A03 OK done 631 4: In this example we see more mailboxes, which reside on another 632 server to which we may obtain referrals. This is similar to the 633 command . Note that in the case of the remote 634 mailboxes, the server might or might not be able to include 635 CHILDREN information; it includes it if it can, and omits it if 636 it can't. 638 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 640 S: * LIST (\Marked \NoInferiors) "/" "inbox" 642 S: * LIST (\HasChildren) "/" "Fruit" 644 S: * LIST (\HasNoChildren) "/" "Tofu" 646 S: * LIST (\HasChildren) "/" "Vegetable" 648 S: * LIST (\Remote) "/" "Bread" 649 S: * LIST (\HasChildren \Remote) "/" "Meat" 651 S: A04 OK done 653 5: The following example also requests the server to include 654 mailboxes, which reside on another server. The server returns 655 information about all mailboxes which are subscribed. This is 656 similar to the command . We also see the use of 657 two selection options. 659 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 661 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 663 S: * LIST (\Subscribed) "/" "Fruit/Banana" 665 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 667 S: * LIST (\Subscribed) "/" "Vegetable" 669 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 671 S: * LIST (\Remote \Subscribed) "/" "Bread" 673 S: A05 OK done 675 6: The following example requests the server to include mailboxes, 676 which reside on another server. The server is requested to 677 return subscription information for all returned mailboxes. This 678 is different from the example above. 680 Note that the output of this command is not a superset of the 681 output in the previous example, as it doesn't include LIST 682 response for the non-existent "Fruit/Peach". 684 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 686 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 688 S: * LIST () "/" "Fruit" 689 S: * LIST () "/" "Fruit/Apple" 691 S: * LIST (\Subscribed) "/" "Fruit/Banana" 693 S: * LIST () "/" "Tofu" 695 S: * LIST (\Subscribed) "/" "Vegetable" 697 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 699 S: * LIST () "/" "Vegetable/Corn" 701 S: * LIST (\Remote \Subscribed) "/" "Bread" 703 S: * LIST (\Remote) "/" "Meat" 705 S: A06 OK done 707 7: In the following example the client has specified multiple 708 mailbox patterns. Note that this example doesn't use the mailbox 709 hierarchy used in the previous examples. 711 C: BBB LIST "" ("INBOX" "Drafts" "Sent/%") 713 S: * LIST () "/" "INBOX" 715 S: * LIST (\NoInferiors) "/" "Drafts" 717 S: * LIST () "/" "Sent/March2004" 719 S: * LIST (\Marked) "/" "Sent/December2003" 721 S: * LIST () "/" "Sent/August2004" 723 S: BBB OK done 725 8: The following example demonstates the difference between 726 \HasChildren attribute and CHILDINFO extended data item. 728 Let's assume there is the following hierarchy: 730 C: C01 LIST "" "*" 732 S: * LIST (\Marked \NoInferiors) "/" "inbox" 734 S: * LIST () "/" "Foo" 736 S: * LIST () "/" "Foo/Bar" 738 S: * LIST () "/" "Foo/Baz" 740 S: * LIST () "/" "Moo" 742 S: C01 OK done 744 If the client asks RETURN (CHILDREN) it will get this: 746 C: CA3 LIST "" "%" RETURN (CHILDREN) 748 S: * LIST (\Marked \NoInferiors) "/" "inbox" 750 S: * LIST (\HasChildren) "/" "Foo" 752 S: * LIST (\HasNoChildren) "/" "Moo" 754 S: CA3 OK done 756 A) Let's also assume that the mailbox "Foo/Baz" is the only 757 subscribed mailbox. Then we get this result: 759 C: C02 LIST (SUBSCRIBED) "" "*" 761 S: * LIST (\Subscribed) "/" "Foo/Baz" 763 S: C02 OK done 765 Now, if the client issues , the server 766 will return no mailboxes (as the mailboxes "Moo", "Foo" and 767 "Inbox" are NOT subscribed). However, if the client issues this: 769 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 770 S: * LIST () "/" "Foo" (("CHILDINFO" ("SUBSCRIBED"))) 772 S: C04 OK done 774 i.e. the mailbox "Foo" is not subscribed, but it has a child that 775 is. 777 A1) If the mailbox "Foo" had been subscribed instead, the last 778 command would return this: 780 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 782 S: * LIST (\Subscribed) "/" "Foo" (("CHILDINFO" 783 ("SUBSCRIBED"))) 785 S: C04 OK done 787 or even this: 789 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 791 S: * LIST (\Subscribed \HasChildren) "/" "Foo" (("CHILDINFO" 792 ("SUBSCRIBED"))) 794 S: C04 OK done 796 A2) If we assume instead that the mailbox "Foo" is not part of 797 the original hierarchy and is not subscribed, the last command 798 will give this result: 800 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 802 S: * LIST (\NonExistent) "/" "Foo" (("CHILDINFO" 803 ("SUBSCRIBED"))) 805 S: C04 OK done 807 B) Now, let's assume that no mailbox is subscribed. In this case 808 the command will return 809 no responses, as there are no subscribed children (even though 810 "Foo" has children). 812 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 813 are subscribed. In that case we see this result: 815 C: LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 817 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 819 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 821 (which means that the mailbox "Foo" has children, but none of 822 them is subscribed). 824 9: The following example demonstrates that the CHILDINFO extended 825 data item is returned whether children mailboxes match the 826 canonical LIST pattern or not. 828 Let's assume there is the following hierarchy: 830 C: D01 LIST "" "*" 832 S: * LIST (\Marked \NoInferiors) "/" "inbox" 834 S: * LIST () "/" "foo2" 836 S: * LIST () "/" "foo2/bar1" 838 S: * LIST () "/" "foo2/bar2" 840 S: * LIST () "/" "baz2" 842 S: * LIST () "/" "baz2/bar2" 844 S: * LIST () "/" "baz2/bar22" 846 S: * LIST () "/" "baz2/bar222" 848 S: * LIST () "/" "eps2" 850 S: * LIST () "/" "eps2/mamba" 852 S: * LIST () "/" "quux2/bar2" 853 S: D01 OK done 855 And that the following mailboxes are subscribed: 857 C: D02 LIST (SUBSCRIBED) "" "*" 859 S: * LIST (\Subscribed) "/" "foo2/bar1" 861 S: * LIST (\Subscribed) "/" "foo2/bar2" 863 S: * LIST (\Subscribed) "/" "baz2/bar2" 865 S: * LIST (\Subscribed) "/" "baz2/bar22" 867 S: * LIST (\Subscribed) "/" "baz2/bar222" 869 S: * LIST (\Subscribed) "/" "eps2" 871 S: * LIST (\Subscribed) "/" "eps2/mamba" 873 S: * LIST (\Subscribed) "/" "quux2/bar2" 875 S: D02 OK done 877 The client issues the following command first: 879 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 881 S: * LIST () "/" "foo2" (("CHILDINFO" ("SUBSCRIBED"))) 883 S: * LIST (\Subscribed) "/" "foo2/bar2" 885 S: * LIST () "/" "baz2" (("CHILDINFO" ("SUBSCRIBED"))) 887 S: * LIST (\Subscribed) "/" "baz2/bar2" 889 S: * LIST (\Subscribed) "/" "baz2/bar22" 891 S: * LIST (\Subscribed) "/" "baz2/bar222" 893 S: * LIST (\Subscribed) "/" "eps2" (("CHILDINFO" 894 ("SUBSCRIBED"))) 895 S: * LIST (\Subscribed) "/" "quux2/bar2" 897 S: D03 OK done 899 and the server may also include 901 S: * LIST (\NonExistent) "/" "quux2" (("CHILDINFO" 902 ("SUBSCRIBED"))) 904 The CHILDINFO extended data item is returned for mailboxes 905 "foo2", "baz2" and "eps2", because all of them have subscribed 906 children, even though for the mailbox "foo2" only one of the two 907 subscribed children match the pattern, for the mailbox "baz2" all 908 the subscribed children match the pattern and for the mailbox 909 "eps2" none of the subscribed children match the pattern. 911 Note that if the client issues 913 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 915 S: * LIST () "/" "foo2" (("CHILDINFO" ("SUBSCRIBED"))) 917 S: * LIST (\Subscribed) "/" "foo2/bar1" 919 S: * LIST (\Subscribed) "/" "foo2/bar2" 921 S: * LIST () "/" "baz2" (("CHILDINFO" ("SUBSCRIBED"))) 923 S: * LIST (\Subscribed) "/" "baz2/bar2" 925 S: * LIST (\Subscribed) "/" "baz2/bar22" 927 S: * LIST (\Subscribed) "/" "baz2/bar222" 929 S: * LIST (\Subscribed) "/" "eps2" (("CHILDINFO" 930 ("SUBSCRIBED"))) 932 S: * LIST (\Subscribed) "/" "eps2/mamba" 934 S: * LIST (\Subscribed) "/" "quux2/bar2" 936 S: D03 OK done 938 the LIST responses for mailboxes "foo2", "baz2" and "eps2" still 939 have the CHILDINFO extended data item, even though this 940 information is redundant and the client can determine it by 941 itself. 943 10: The following example shows usage of multiple mailbox patterns. 944 It also demonstrates that the presence of the CHILDINFO extended 945 data item doesn't necessarily imply \HasChildren. 947 C: a1 LIST "" ("foo" "foo/*") 949 S: * LIST () "/" foo 951 S: a1 OK done 953 C: a2 LIST (SUBSCRIBED) "" "foo/*" 955 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 957 S: a2 OK done 959 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN 960 (CHILDREN) 962 S: * LIST (\HasNoChildren) "/" foo (("CHILDINFO" 963 ("SUBSCRIBED"))) 965 S: a3 OK done 967 6. Formal Syntax 969 The following syntax specification uses the augmented Backus-Naur 970 Form (BNF) as described in [ABNF]. Terms not defined here are taken 971 from [IMAP4]. 973 "vendor-token" is defined in [ACAP]. Note that this normative 974 reference to ACAP is an issue in moving this spec forward, since ACAP 975 will never move to Draft Standard. The definitions of "vendor-token" 976 and of the IANA registry must eventually go somewhere else, in a 977 document that can be moved forward on the standards track. 979 childinfo-extended-item = "CHILDINFO" SP "(" list-select-base-opt- 980 quoted 981 *( SP list-select-base-opt-quoted ) ")" 982 ; Extended data item returned when the RECURSIVEMATCH 983 ; selection option is specified. 984 ; Note 1: the CHILDINFO tag can be returned 985 ; with and without surrounding quotes, as per 986 ; mbox-list-extended-item-tag production. 987 ; Note 2: The selection options are returned quoted, 988 ; unlike their specification in the extended LIST 989 ; command. 991 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 992 ; attributes for CHILDREN return option, at most one 993 ; possible per LIST response 995 eitem-standard-tag = atom 996 ; a tag for extended list data defined in a Standard 997 ; Track or Experimental RFC. 999 eitem-vendor-tag = vendor-tag 1000 ; a vendor specific tag for extended list data 1002 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 1003 [SP list-return-opts] 1005 list-select-opts = "(" [*(list-select-mod-opt SP) list-select-base- 1006 opt 1007 *(SP list-select-opt)] ")" 1008 ; list selection options, e.g. REMOTE 1010 list-select-opt = list-select-mod-opt / list-select-base-opt 1011 ; An option registration template is described in 1012 ; Section 8.3 of this document. 1014 list-select-base-opt = "SUBSCRIBED" / "REMOTE" / option-extension 1015 ; options that can be used by themselves 1017 list-select-base-opt-quoted = <"> list-select-base-opt <"> 1019 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 1020 ; options that require a list-select-base-opt 1021 ; to also be present 1023 list-return-opts = "RETURN" SP "(" [return-option *(SP return- 1024 option)] ")" 1025 ; list return options, e.g. CHILDREN 1027 mailbox-list = "(" [mbx-list-flags] ")" SP 1028 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 1029 [SP mbox-list-extended] 1031 mbox-list-extended = "(" [mbox-list-extended-item 1032 *(SP mbox-list-extended-item)] ")" 1034 mbox-list-extended-item = "(" mbox-list-extended-item-data ")" 1036 mbox-list-extended-item-data = mbox-list-extended-item-tag SP 1037 nstring-list 1039 mbox-list-extended-item-tag = astring 1040 ; The content MUST conform to either "eitem-vendor-tag" 1041 ; or "eitem-standard-tag" ABNF productions. 1042 ; A tag registration template is described in this 1043 document 1044 ; in Section 8.5. 1046 mbox-list-oflag = child-mbox-flag / "\NonExistent" / 1047 / "\Subscribed" / "\Remote" 1049 mbox-or-pat = list-mailbox / patterns 1051 nstring-list = nstring / 1052 "(" [nstring-list *(SP nstring-list)] ")" 1053 ; a recursive list definition 1055 option-extension = option-vendor-tag / option-standard-tag 1057 option-vendor-tag = vendor-tag 1058 ; a vendor specific option 1060 option-standard-tag = atom 1061 ; an option defined in a Standard Track or 1062 ; Experimental RFC 1064 patterns = "(" list-mailbox *(SP list-mailbox) ")" 1066 return-option = "SUBSCRIBED" / "CHILDREN" / 1067 option-extension 1069 vendor-tag = vendor-token "-" atom 1071 7. Security Considerations 1073 This document describes syntactic changes to the specification of the 1074 IMAP4 commands LIST, LSUB, RLIST, and RLSUB, and the modified LIST 1075 command has the same security considerations as those commands. They 1076 are described in [IMAP4] and [MBRef]. 1078 The Child Mailbox Extension provides a client a more efficient means 1079 of determining whether a particular mailbox has children. If a 1080 mailbox has children, but the currently authenticated user does not 1081 have access to any of them, the server SHOULD respond with a 1082 \HasNoChildren attribute. In many cases, however, a server may not 1083 be able to efficiently compute whether a user has access to all child 1084 mailboxes. If such a server responds with a \HasChildren attribute, 1085 when in fact the currently authenticated user does not have access to 1086 any child mailboxes, potentially more information is conveyed about 1087 the mailbox than intended. In most situations this will not be a 1088 security concern, because if information regarding whether a mailbox 1089 has children is considered sensitive, a user would not be granted 1090 access to that mailbox in the first place. 1092 The CHILDINFO extended data item has the same security considerations 1093 as the \HasChildren attribute described above. 1095 8. IANA Considerations 1097 8.1 Guidelines for IANA 1099 It is requested that IANA creates two new registries for LIST- 1100 EXTENDED options and LIST-EXTENDED response data. The templates and 1101 the initial registrations are detailed below. 1103 8.2 Registration procedure and Change control 1105 Registration of a LIST-EXTENDED option is done by filling in the 1106 template in Section 8.3 and sending it via electronic mail to 1107 iana@iana.org. Registration of a LIST-EXTENDED extended data item is 1108 done by filling in the template in Section 8.5 and sending it via 1109 electronic mail to iana@iana.org. IANA has the right to reject 1110 obviously bogus registrations, but will perform no review of claims 1111 made in the registration form. 1113 A LIST-EXTENDED option/extended data item name that starts with "V-" 1114 is reserved for vendor specific options/extended data items. All 1115 options, whether they are vendor specific or global, should be 1116 registered with IANA. If a LIST-EXTENDED extended data item is 1117 returned as a result of requesting a particular LIST-EXTENDED option, 1118 the name of the option SHOULD be used as the name of the LIST- 1119 EXTENDED extended data item. 1121 Each vendor specific options/extended data item MUST start with their 1122 vendor-token ("vendor prefix"). The vendor-token MUST be registered 1123 with IANA, using the [ACAP] vendor subtree registry. 1125 Standard LIST-EXTENDED option/extended data item names are case 1126 insensitive. If the vendor prefix is omitted from a vendor specific 1127 LIST-EXTENDED option/extended data item name, the rest is case 1128 insensitive. The vendor prefix itself is not case-sensitive, as it 1129 might contain non-ASCII characters. 1131 While the registration procedures do not require it, authors of LIST- 1132 EXTENDED options/extended data items are encouraged to seek community 1133 review and comment whenever that is feasible. Authors may seek 1134 community review by posting a specification of their proposed 1135 mechanism as an Internet- Draft. LIST-EXTENDED options/extended data 1136 items intended for widespread use should be standardized through the 1137 normal IETF process, when appropriate. 1139 Comments on registered LIST-EXTENDED options/extended response data 1140 should first be sent to the "owner" of the mechanism and/or to the 1141 IMAPEXT WG mailing list. Submitters of comments may, after a 1142 reasonable attempt to contact the owner, request IANA to attach their 1143 comment to the registration itself. If IANA approves of this, the 1144 comment will be made accessible in conjunction with the registration 1145 LIST-EXTENDED options/ extended response data itself. 1147 Once a LIST-EXTENDED registration has been published by IANA, the 1148 author may request a change to its definition. The change request 1149 follows the same procedure as the registration request. 1151 The owner of a LIST-EXTENDED registration may pass responsibility for 1152 the registered option/extended data item to another person or agency 1153 by informing IANA; this can be done without discussion or review. 1155 The IESG may reassign responsibility for a LIST-EXTENDED option/ 1156 extended data item. The most common case of this will be to enable 1157 changes to be made to mechanisms where the author of the registration 1158 has died, moved out of contact or is otherwise unable to make changes 1159 that are important to the community. 1161 LIST-EXTENDED registrations may not be deleted; mechanisms which are 1162 no longer believed appropriate for use can be declared OBSOLETE by a 1163 change to their "intended use" field; such LIST-EXTENDED options/ 1164 extended data items will be clearly marked in the lists published by 1165 IANA. 1167 The IESG is considered to be the owner of all LIST-EXTENDED options/ 1168 extended data items which are on the IETF standards track. 1170 8.3 Registration template for LIST-EXTENDED options 1172 To: iana@iana.org 1173 Subject: Registration of LIST-EXTENDED option X 1175 LIST-EXTENDED option name: 1177 LIST-EXTENDED option type: (One of SELECTION or RETURN) 1179 Implied return options(s), if the option type is SELECTION: (zero or 1180 more) 1182 LIST-EXTENDED option description: 1184 Published specification (optional, recommended): 1186 Security considerations: 1188 Intended usage: 1189 (One of COMMON, LIMITED USE or OBSOLETE) 1190 Person and email address to contact for further information: 1192 Owner/Change controller: 1194 (Any other information that the author deems interesting may be added 1195 below this line.) 1197 8.4 Initial LIST-EXTENDED option registrations 1199 It is requested that the LIST-EXTENDED option registry be populated 1200 with the following entries: 1202 1. To: iana@iana.org 1203 Subject: Registration of LIST-EXTENDED option SUBSCRIBED 1205 LIST-EXTENDED option name: SUBSCRIBED 1207 LIST-EXTENDED option type: SELECTION 1209 Implied return options(s): SUBSCRIBED 1211 LIST-EXTENDED option description: Causes the LIST command to list 1212 subscribed mailboxes, rather than the actual mailboxes. 1214 Published specification : XXXX, Section 3. 1216 Security considerations: XXXX, Section 7. 1218 Intended usage: COMMON 1220 Person and email address to contact for further information: 1221 Alexey Melnikov 1223 Owner/Change controller: iesg@ietf.org 1225 2. To: iana@iana.org 1226 Subject: Registration of LIST-EXTENDED option REMOTE 1228 LIST-EXTENDED option name: REMOTE 1230 LIST-EXTENDED option type: SELECTION 1232 Implied return options(s): (none) 1234 LIST-EXTENDED option description: causes the LIST command to 1235 return remote mailboxes as well as local ones, as described in 1236 RFC 2193. 1238 Published specification : XXXX, Section 3. 1240 Security considerations: XXXX, Section 7. 1242 Intended usage: COMMON 1244 Person and email address to contact for further information: 1245 Alexey Melnikov 1247 Owner/Change controller: iesg@ietf.org 1249 3. To: iana@iana.org 1250 Subject: Registration of LIST-EXTENDED option SUBSCRIBED 1252 LIST-EXTENDED option name: SUBSCRIBED 1254 LIST-EXTENDED option type: RETURN 1256 LIST-EXTENDED option description: Causes the LIST command to 1257 return subscription state. 1259 Published specification : XXXX, Section 3. 1261 Security considerations: XXXX, Section 7. 1263 Intended usage: COMMON 1265 Person and email address to contact for further information: 1266 Alexey Melnikov 1268 Owner/Change controller: iesg@ietf.org 1270 4. To: iana@iana.org 1271 Subject: Registration of LIST-EXTENDED option RECURSIVEMATCH 1273 LIST-EXTENDED option name: RECURSIVEMATCH 1275 LIST-EXTENDED option type: SELECTION 1277 Implied return options(s): (none) 1279 LIST-EXTENDED option description: Requests that CHILDINFO 1280 extended data item is to be returned. 1282 Published specification : XXXX, Section 3. 1284 Security considerations: XXXX, Section 7. 1286 Intended usage: COMMON 1288 Person and email address to contact for further information: 1289 Alexey Melnikov 1291 Owner/Change controller: iesg@ietf.org 1293 5. To: iana@iana.org 1294 Subject: Registration of LIST-EXTENDED option CHILDREN 1296 LIST-EXTENDED option name: CHILDREN 1298 LIST-EXTENDED option type: RETURN 1300 LIST-EXTENDED option description: Requests mailbox child 1301 information. 1303 Published specification : XXXX, Section 3 and Section 4. 1305 Security considerations: XXXX, Section 7. 1307 Intended usage: COMMON 1309 Person and email address to contact for further information: 1310 Alexey Melnikov 1312 Owner/Change controller: iesg@ietf.org 1314 8.5 Registration template for LIST-EXTENDED extended data item 1316 To: iana@iana.org 1317 Subject: Registration of X LIST-EXTENDED extended data item 1319 LIST-EXTENDED extended data item tag: 1321 LIST-EXTENDED extended data item description: 1323 Which LIST-EXTENDED option(s) (and their types) causes this extended 1324 data item to be returned (if any): 1326 Published specification (optional, recommended): 1328 Security considerations: 1330 Intended usage: 1331 (One of COMMON, LIMITED USE or OBSOLETE) 1333 Person and email address to contact for further information: 1335 Owner/Change controller: 1337 (Any other information that the author deems interesting may be added 1338 below this line.) 1340 8.6 Initial LIST-EXTENDED extended data item registrations 1342 It is requested that the LIST-EXTENDED extended data item registry be 1343 populated with the following entries: 1345 1. To: iana@iana.org 1346 Subject: Registration of CHILDINFO LIST-EXTENDED extended data 1347 item 1349 LIST-EXTENDED extended data item tag: CHILDINFO 1351 LIST-EXTENDED extended data item description: The CHILDINFO 1352 extended data item describes the selection criteria that has 1353 caused it to be returned and indicates that the mailbox has one 1354 or more child mailbox that match the selection criteria. 1356 Which LIST-EXTENDED option(s) (and their types) causes this 1357 extended data item to be returned (if any): RECURSIVEMATCH 1358 selection option 1360 Published specification : XXXX, Section 3.3. 1362 Security considerations: XXXX, Section 7. 1364 Intended usage: COMMON 1366 Person and email address to contact for further information: 1367 Alexey Melnikov 1369 Owner/Change controller: iesg@ietf.org 1371 9. Acknowledgements 1373 Mike Gahrns and Raymond Cheng of Microsoft Corporation originally 1374 devised the Child Mailbox Extension and proposed it in 1997; the 1375 idea, as well as most of the text in Section 4, is theirs. 1377 This document is the result of discussions on the IMAP4 and IMAPEXT 1378 mailing lists and is meant to reflect consensus of those groups. In 1379 particular, Mark Crispin, Philip Guenther, Cyrus Daboo, Timo 1380 Sirainen, Ken Murchison, Rob Siemborski, Steve Hole, Arnt 1381 Gulbrandsen, Larry Greenfield, Dave Cridland and Pete Maclean were 1382 active participants in those discussions or made suggestions to this 1383 document. 1385 10. Normative References 1387 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 1388 Specifications: ABNF", RFC 2234, November 1997. 1390 [ACAP] Newman, C. and J. Myers, "ACAP -- Application Configuration 1391 Access Protocol", RFC 2244, November 1997. 1393 [CMbox] Gahrns, M. and R. Cheng, "", RFC 3348, July 2002. 1395 [IMAP4] Crispin, M., "Internet Message Access Protocol - Version 1396 4rev1", RFC 3501, March 2003. 1398 [Kwds] Bradner, S., "Key words for use in RFCs to Indicate 1399 Requirement Levels", RFC 2119, March 1997. 1401 [MBRef] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 1402 September 1997. 1404 Authors' Addresses 1406 Barry Leiba 1407 IBM T.J. Watson Research Center 1408 30 Saw Mill River Road 1409 Hawthorne, NY 10532 1410 US 1412 Phone: +1 914 784 7941 1413 Email: leiba@watson.ibm.com 1414 Alexey Melnikov 1415 Isode Limited 1416 5 Castle Business Village 1417 36 Station Road 1418 Hampton, Middlesex TW12 2BX 1419 UK 1421 Email: Alexey.Melnikov@isode.com 1422 URI: http://www.melnikov.ca/ 1424 Intellectual Property Statement 1426 The IETF takes no position regarding the validity or scope of any 1427 Intellectual Property Rights or other rights that might be claimed to 1428 pertain to the implementation or use of the technology described in 1429 this document or the extent to which any license under such rights 1430 might or might not be available; nor does it represent that it has 1431 made any independent effort to identify any such rights. 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