draft-ietf-imapext-list-extensions-09.txt   draft-ietf-imapext-list-extensions-10.txt 
IMAP Extensions Working Group B. Leiba IMAP Extensions Working Group B. Leiba
Internet Draft IBM T.J. Watson Research Center Internet Draft IBM T.J. Watson Research Center
A. Melnikov A. Melnikov
Isode Limited Isode Limited
Expires March 2005 September 2004 Expires April 2005 October 2004
IMAP4 LIST Command Extensions IMAP4 LIST Command Extensions
draft-ietf-imapext-list-extensions-09.txt draft-ietf-imapext-list-extensions-10.txt
Status of this Document Status of this Document
By submitting this Internet-Draft, I certify that any applicable By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed, or patent or other IPR claims of which I am aware have been disclosed, or
will be disclosed, and any of which I become aware will be disclosed, will be disclosed, and any of which I become aware will be disclosed,
in accordance with RFC 3668. in accordance with RFC 3668.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at line 36 skipping to change at line 36
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
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A revised version of this draft document will be submitted to the RFC A revised version of this draft document will be submitted to the RFC
editor as an Proposed Standard for the Internet Community. editor as an Proposed Standard for the Internet Community.
Discussion and suggestions for improvement are requested, and should Discussion and suggestions for improvement are requested, and should
be sent to ietf-imapext@imc.org. This document will expire before 31 be sent to ietf-imapext@imc.org.
November 2004. Distribution of this memo is unlimited.
This documents obsoletes RFC 3348 and updates RFC 2193. This documents obsoletes RFC 3348 and updates RFC 2193.
Abstract Abstract
IMAP4 has two commands for listing mailboxes: LIST and LSUB. As we IMAP4 has two commands for listing mailboxes: LIST and LSUB. As we
have added extensions that have required specialized lists (see have added extensions that have required specialized lists (see
[MboxRefer] for an example) we have had to expand the number of list [MboxRefer] for an example) we have had to expand the number of list
commands, since each extension must add its function to both LIST and commands, since each extension must add its function to both LIST and
LSUB, and these commands are not, as they are defined, extensible. LSUB, and these commands are not, as they are defined, extensible.
skipping to change at line 75 skipping to change at line 74
the reference and mailbox name arguments (Section 6.3.8 of [IMAP4]). the reference and mailbox name arguments (Section 6.3.8 of [IMAP4]).
The [IMAP4] LIST command returns only mailboxes that match the The [IMAP4] LIST command returns only mailboxes that match the
canonical LIST pattern. canonical LIST pattern.
Other terms are introduced where they are referenced for the first time. Other terms are introduced where they are referenced for the first time.
<<Other editorial comments/questions are enclosed like this.>> <<Other editorial comments/questions are enclosed like this.>>
2. Introduction and overview 2. Introduction and overview
The extensions to the LIST command will be accomplished by amending The extensions to the LIST command is accomplished by amending
the syntax to allow options to be specified. The list of options the syntax to allow options to be specified. The list of options
will replace the several commands that are currently used to mix and replaces the several commands that are currently used to mix and
match the information requested. The new syntax is backward- match the information requested. The new syntax is backward-
compatible, with no ambiguity: the new syntax is being used if one of compatible, with no ambiguity: the new syntax is being used if one of
the following conditions is true: the following conditions is true:
1). if the first word after the command name begins with a parenthesis; 1). if the first word after the command name begins with a
2). if the second word after the command name begins with a parenthesis; parenthesis ("LIST selection options");
3). if the LIST command has more than 2 parameters; 2). if the second word after the command name begins with a
parenthesis ("multiple mailbox patterns");
3). if the LIST command has more than 2 parameters
("LIST return options");
Otherwise the original syntax is used. Otherwise the original syntax is used.
By adding options to the LIST command, we are announcing the intent By adding options to the LIST command, we are announcing the intent
to phase out and eventually to deprecate the RLIST and RLSUB commands to phase out and eventually to deprecate the RLIST and RLSUB commands
described in [MboxRefer]. We are also defining the mechanism to described in [MboxRefer]. We are also defining the mechanism to
request extended mailbox information, such as is described in the request extended mailbox information, such as is described in the
"Child Mailbox Extension" [ChildMbox]. The base "Child Mailbox Extension" [ChildMbox]. The base
LSUB command is not deprecated by this extension; rather, this LSUB command is not deprecated by this extension; rather, this
extension adds a way to obtain subscription information with more extension adds a way to obtain subscription information with more
options, with those server implementations that support it. Clients options, with those server implementations that support it. Clients
that simply need a list of subscribed mailboxes, as provided by the that simply need a list of subscribed mailboxes, as provided by the
LSUB command, SHOULD continue to use that command. LSUB command, SHOULD continue to use that command.
This document defines an IMAP4 extension that is identified by the This document defines an IMAP4 extension that is identified by the
capability string "X-DRAFT-W09-LISTEXT" <<Note to the RFC Editor: capability string "X-DRAFT-W10-LISTEXT" <<Note to the RFC Editor:
the capability name will change upon publication as an RFC>>. the capability name will change upon publication as an RFC>>.
The X-DRAFT-W09-LISTEXT extension makes the The X-DRAFT-W10-LISTEXT extension makes the
following changes to the IMAP4 protocol, which are described in following changes to the IMAP4 protocol, which are described in
more details in sections 3 and 4 of this document: more details in sections 3 and 4 of this document:
a. defines new syntax for LIST command options. a. defines new syntax for LIST command options.
b. extend LIST to allow for multiple mailbox patterns. b. extend LIST to allow for multiple mailbox patterns.
c. adds LIST command selection options: SUBSCRIBED, REMOTE and MATCHPARENT. c. adds LIST command selection options: SUBSCRIBED, REMOTE and
MATCHPARENT.
d. adds LIST command return options: SUBSCRIBED and CHILDREN. d. adds LIST command return options: SUBSCRIBED and CHILDREN.
e. adds new mailbox attributes: "\NonExistent", "\PlaceHolder", e. adds new mailbox attributes: "\NonExistent", "\PlaceHolder",
"\Subscribed", "\Remote", "\HasSubmailboxes", "\Subscribed", "\Remote", "\HasSubMailboxes",
"\HasChildren" and "\HasNoChildren". "\HasChildren" and "\HasNoChildren".
3. LIST Command Options 3. Extended LIST Command
This extension updates the syntax of the LIST command to allow for multiple This extension updates the syntax of the LIST command to allow for multiple
mailbox patterns to be specified, if they are enclosed in parantheses. mailbox patterns to be specified, if they are enclosed in parantheses.
A mailbox match a list of mailbox patterns, if it matches at least one A mailbox name match a list of mailbox patterns if it matches at least
mailbox pattern. one mailbox pattern. Note that if a mailbox name matches multiple mailbox
patterns from the list, the server should return only a single LIST
response.
Note that the non-extended LIST command is required to treat an empty
("" string) mailbox name argument as a special request to return the
hierarchy delimiter and the root name of the name given in the
reference parameter (as per [IMAP4]). However ANY extended LIST command
(extended in any of 3 ways specified in section 2, or any combination of
therof) MUST NOT treat the empty mailbox name as such special request
and any regular processing described in this document applies.
In particular, if an extended LIST command has multiple mailbox names
and one (or more) of them is the empty string, the empty string MUST be
ignored for the purpose of matching. <<Open issue: what if one of the
mailbox patterns is invalid for the server? Does it have to reject the
LIST command with BAD response, or should it just ignore invalid patterns?>>
The LIST command syntax is also extended in two additional ways: by adding a The LIST command syntax is also extended in two additional ways: by adding a
parenthesized list of command options between the command name and the reference parenthesized list of command options between the command name and the
name (LIST selection options) and an optional list of options at the end that reference name (LIST selection options) and an optional list of options at
control what kind of information should be returned (LIST return options). the end that control what kind of information should be returned (LIST return
See the formal syntax in section 6 for specific details. A LIST selection option options). See the formal syntax in section 6 for specific details.
tells the server which mailbox names should be selected by the LIST operation.
The server should return information about all mailbox names that match any of the A LIST selection option tells the server which mailbox names should be
"canonical LIST pattern" (as described above) and satisfy additional selection selected by the LIST operation.
criteria (if any) specified by the LIST selection options. Let's call any such The server should return information about all mailbox names that match any
mailbox name a "matched mailbox name". of the "canonical LIST pattern" (as described above) and satisfy additional
selection criteria (if any) specified by the LIST selection options. Let's
call any such mailbox name a "matched mailbox name".
When multiple selection options are specified, the server must return When multiple selection options are specified, the server must return
information about mailbox names that satisfy every selection option, unless information about mailbox names that satisfy every selection option, unless
a description of a particular specified option prescribes special rules. a description of a particular specified option prescribes special rules.
An example of an option prescribing special rules is the MATCHPARENT selection An example of an option prescribing special rules is the MATCHPARENT
option described later in this section. selection option described later in this section.
We will use the term "selection criteria" when refering collectively to all We will use the term "selection criteria" when referring collectively to all
selection options specified in a LIST command. selection options specified in a LIST command.
A LIST return option controls which information is returned for each matched A LIST return option controls which information is returned for each matched
mailbox name. Note, that return options MUST NOT cause the server to report mailbox name. Note that return options MUST NOT cause the server to report
information about additional mailbox names. If the client has not specified any information about additional mailbox names. If the client has not specified
return option, only information about attributes should be returned by the server. any return option, only information about attributes should be returned by
(Of course the server is allowed to include any other information at will) the server. (Of course the server is allowed to include any other information
at will)
Both selection and return command options will be defined in this document and Both selection and return command options will be defined in this document
in approved extension documents; each option will be enabled by a capability and in approved extension documents; each option will be enabled by a
string (one capability may enable multiple options), and a client MUST NOT capability string (one capability may enable multiple options), and a client
send an option for which the server has not advertised support. A server MUST NOT send an option for which the server has not advertised support.
MUST respond to options it does not recognize with a NO response. A server MUST respond to options it does not recognize with a BAD response.
The client SHOULD NOT specify any option more than once, however if the
client does this, the server MUST act as if it recieved the option only once.
This extension is identified by the capability string "X-DRAFT-W09-LISTEXT" This extension is identified by the capability string "X-DRAFT-W10-LISTEXT"
<<Note to the RFC editor: please update upon publication as above>>, and <<Note to the RFC editor: please update upon publication as above>>, and
support for it is a prerequisite for any future extensions that support for it is a prerequisite for any future extensions that
require specialized forms of the LIST command. Such extensions MUST require specialized forms of the LIST command. Such extensions MUST
refer to this document and MUST add their function through command refer to this document and MUST add their function through command
options as described herein. options as described herein.
Note, that extensions that don't require support for an extended LIST command, Note that extensions that don't require support for an extended LIST
but use extended LIST responses (see below), don't need to advertise the command, but use extended LIST responses (see below), don't need to advertise
"X-DRAFT-W09-LISTEXT" capability string. <<Note to the RFC Editor: fix upon the "X-DRAFT-W10-LISTEXT" capability string. <<Note to the RFC Editor: fix
publication as above>> upon publication as above>>
This extension also defines extensions to the LIST response, allowing This extension also defines extensions to the LIST response, allowing
a series of extended fields at the end, a parenthesized list of tagged a series of extended fields at the end, a parenthesized list of tagged
data (also referred to as "extended data item"). The first element of data (also referred to as "extended data item"). The first element of
an extended field is a tag, which identifies type of the data. Tags an extended field is a tag, which identifies type of the data. Tags
MUST be registered with IANA, as described in section 8.5 of this MUST be registered with IANA, as described in section 8.5 of this
document. An example of such extended set might be document. An example of such extended set might be
((tablecloth (("fringe" "lacy")("color" "white")))(X-Sample ((tablecloth (("fringe" "lacy")("color" "white")))(X-Sample
"text")) "text"))
or... or...
((tablecloth ("fringe" "lacy"))(X-Sample "text" "and even more text")) ((tablecloth ("fringe" "lacy"))(X-Sample "text" "and even more text"))
See the formal grammar, below, for the full syntactic details. See the formal grammar, below, for the full syntactic details.
The server MAY return data in the extended fields that was not solicited The server MAY return data in the extended fields that was not solicited
by the client. The client MUST ignore all extended fields it doesn't by the client. The client MUST ignore all extended fields it doesn't
recognize. recognize.
The X-DRAFT-W09-LISTEXT <<Note to the RFC Editor: fix upon publication>> The X-DRAFT-W10-LISTEXT <<Note to the RFC Editor: fix upon publication>>
capability also defines several new mailbox attributes. capability also defines several new mailbox attributes.
The "\PlaceHolder" attribute indicates that the designated mailbox does not The "\PlaceHolder" attribute indicates that the designated mailbox does not
meet the selection criteria of the given LIST command, but that it meet the selection criteria of the given LIST command, but that it
has one or more child mailbox that might (unspecified whether any, has one or more child mailbox that might (unspecified whether any,
all, or none match the canonical LIST pattern). all, or none match the canonical LIST pattern).
The LSUB command indicates this condition by using the "\NoSelect" The LSUB command indicates this condition by using the "\NoSelect"
attribute, but the LIST (SUBSCRIBED) command MUST NOT do that, since attribute, but the LIST (SUBSCRIBED) command MUST NOT do that, since
"\NoSelect" retains its original meaning here. Further, the "\NoSelect" retains its original meaning here. Further, the
"\PlaceHolder" attribute is more general, in that it can be used with any "\PlaceHolder" attribute is more general, in that it can be used with any
extended set of selection criteria. extended set of selection criteria.
The "\HasSubmailboxes" attribute indicates that the designated mailbox meets The "\HasSubMailboxes" attribute indicates that the designated mailbox meets
the selection criteria of the given LIST command and also has one or more the selection criteria of the given LIST command and also has one or more
child mailbox that might (unspecified whether any, all, or none match the child mailbox that might (unspecified whether any, all, or none match the
canonical LIST pattern). canonical LIST pattern).
The MATCHPARENT selection option described below REQUIRES that the The "\Placeholder" and the "\HasSubMailboxes" attributes MUST only be
"\Placeholder" and the "\HasSubmailboxes" attributes be accurately computed. returned when the client has specified the MATCHPARENT selection option.
When the MATCHPARENT selection option was specified by the client, When the MATCHPARENT selection option was specified by the client,
the absence of both \PlaceHolder and \HasSubmailboxes means that the the absence of both \PlaceHolder and \HasSubMailboxes means that the
mailbox meets the selection criteria, but doesn't have any children that mailbox meets the selection criteria, but doesn't have any children that
also meets the selection criteria and doesn't match the canonical LIST pattern. also meets the selection criteria and doesn't match the canonical LIST
However, absence of both \PlaceHolder and \HasSubmailboxes doesn't tell pattern. However, absence of both \PlaceHolder and \HasSubMailboxes doesn't
whether there are any children that meet the selection criteria and match tell whether there are any children that meet the selection criteria and
the canonical LIST pattern. match the canonical LIST pattern.
The "\PlaceHolder" and the "\HasSubmailboxes" attributes are mutually The "\PlaceHolder" and the "\HasSubMailboxes" attributes are mutually
exclusive. exclusive.
The presence of a "\Placeholder"/""\HasSubmailboxes" attribute implies Examples 8 and 10 in section 5 demonstrates the difference between
"\HasChildren". "\Placeholder"/""\HasSubMailboxes" and "\HasChildren" attributes.
The example 8 in section 5 demonstrates the difference between
"\Placeholder"/""\HasSubmailboxes" and "\HasChildren" attributes.
The "\NonExistent" attribute indicates that a mailbox does not actually exist. The "\NonExistent" attribute indicates that a mailbox does not actually
Note that this attribute is not meaningful by itself, as mailboxes that match exist. Note that this attribute is not meaningful by itself, as mailboxes
the canonical LIST pattern but don't exist must not be returned unless one that match the canonical LIST pattern but don't exist must not be returned
of the two conditions listed below is also satisfied: unless one of the two conditions listed below is also satisfied:
a) the mailbox also satisfy the selection criteria a) the mailbox also satisfies the selection criteria
b) the mailbox has at least one child mailbox that satisfies the selection b) the mailbox has at least one child mailbox that satisfies the selection
criteria, but doesn't match the canonical LIST pattern. criteria, but doesn't match the canonical LIST pattern.
In practice this means that the "\NonExistent" attribute is usually returned In practice this means that the "\NonExistent" attribute is usually returned
with one or more of "\PlaceHolder"/"\HasSubmailboxes", "\Subscribed", with one or more of "\PlaceHolder"/"\HasSubMailboxes", "\Subscribed",
"\Remote" (see their description below). "\Remote" (see their description below).
The "\NonExistent" attribute implies "\NoSelect". The "\NonExistent" attribute implies "\NoSelect". The "\NonExistent"
The "\NonExistent" attribute MUST be supported and MUST be accurately computed. attribute MUST be supported and MUST be accurately computed.
The following table summarizes when "\NonExistent", "\PlaceHolder" or The following table summarizes when "\NonExistent", "\PlaceHolder" or
"\HasSubmailboxes" attributes are to be returned: "\HasSubMailboxes" attributes are to be returned (Note that
"\PlaceHolder" or "\HasSubMailboxes" attributes are only returned
when MATCHPARENT selection option is specified):
+------+------------+---------------------+--------------------------------+ +------+------------+---------------------+--------------------------------+
|exists| meets the | has a child that | returned | |exists| meets the | has a child that | returned |
| | selection | meets the selection | LISTEXT attributes | | | selection | meets the selection | LISTEXT attributes |
| | criteria | criteria | | | | criteria | criteria | |
+------+------------+---------------------+--------------------------------+ +------+------------+---------------------+--------------------------------+
| no | no | no | no LIST response returned | | no | no | no | no LIST response returned |
| yes | no | no | no LIST response returned | | yes | no | no | no LIST response returned |
| no | yes | no | (\NonExistent) | | no | yes | no | (\NonExistent) |
| yes | yes | no | () | | yes | yes | no | () |
| no | no | yes | (\NonExistent \PlaceHolder) | | no | no | yes | (\NonExistent \PlaceHolder) |
| yes | no | yes | (\PlaceHolder) | | yes | no | yes | (\PlaceHolder) |
| no | yes | yes | (\NonExistent \HasSubmailboxes)| | no | yes | yes | (\NonExistent \HasSubMailboxes)|
| yes | yes | yes | (\HasSubmailboxes) | | yes | yes | yes | (\HasSubMailboxes) |
+------+------------+---------------------+--------------------------------+ +------+------------+---------------------+--------------------------------+
The selection options defined in this specification are The selection options defined in this specification are
SUBSCRIBED - causes the LIST command to list subscribed SUBSCRIBED - causes the LIST command to list subscribed
names, rather than the actual mailboxes. This will often names, rather than the existing mailboxes. This will often
be a subset of the actual mailboxes. It's also possible for be a subset of the actual mailboxes. It's also possible for
this list to contain the names of mailboxes that don't exist. this list to contain the names of mailboxes that don't exist.
In any case, the list MUST include exactly those mailbox names In any case, the list MUST include exactly those mailbox names
that match the canonical list pattern and are subscribed to. This that match the canonical list pattern and are subscribed to. This
option is intended to supplement the LSUB command. option is intended to supplement the LSUB command.
Of particular note are the mailbox attributes as returned by this Of particular note are the mailbox attributes as returned by this
option, compared with what is returned by LSUB. With the option, compared with what is returned by LSUB. With the
latter, the attributes returned may not reflect the actual attribute latter, the attributes returned may not reflect the actual attribute
status on the mailbox name, and the \NoSelect attribute has a special status on the mailbox name, and the \NoSelect attribute has a special
meaning (it indicates that this mailbox is not, itself, meaning (it indicates that this mailbox is not, itself,
subscribed, but that it has child mailboxes that are). With subscribed, but that it has child mailboxes that are). With
the SUBSCRIBED selection option described here, the attributes are the SUBSCRIBED selection option described here, the attributes are
accurate and complete, and have no special meanings. accurate, complete, and have no special meanings.
"LSUB" and "LIST (SUBSCRIBED)" are, thus, not the same thing, "LSUB" and "LIST (SUBSCRIBED)" are, thus, not the same thing,
and some servers must do significant extra work to respond to and some servers must do significant extra work to respond to
"LIST (SUBSCRIBED)". Because of this, clients SHOULD continue "LIST (SUBSCRIBED)". Because of this, clients SHOULD continue
to use "LSUB" unless they specifically want the additional to use "LSUB" unless they specifically want the additional
information offered by "LIST (SUBSCRIBED)". information offered by "LIST (SUBSCRIBED)".
This option defines a new mailbox attribute, "\Subscribed" that This option defines a new mailbox attribute, "\Subscribed", that
indicates that a mailbox name is subscribed to. The "\Subscribed" indicates that a mailbox name is subscribed to. The "\Subscribed"
attribute MUST be supported and MUST be accurately computed attribute MUST be supported and MUST be accurately computed
when the SUBSCRIBED selection option is specified. when the SUBSCRIBED selection option is specified.
Note, that the SUBSCRIBED selection option implies the SUBSCRIBED Note that the SUBSCRIBED selection option implies the SUBSCRIBED
return option (see below). return option (see below).
REMOTE - causes the LIST command to show remote mailboxes as REMOTE - causes the LIST command to show remote mailboxes as
well as local ones, as described in [MboxRefer]. This option well as local ones, as described in [MboxRefer]. This option
is intended to replace the RLIST command and, in conjunction is intended to replace the RLIST command and, in conjunction
with the SUBSCRIBED selection option, the RLSUB command. with the SUBSCRIBED selection option, the RLSUB command.
This option defines a new mailbox attribute, "\Remote", that This option defines a new mailbox attribute, "\Remote", that
indicates that a mailbox is a remote mailbox. The "\Remote" indicates that a mailbox is a remote mailbox. The "\Remote"
attribute MUST be accurately computed when the REMOTE option is attribute MUST be accurately computed when the REMOTE option is
specified. specified.
Note, that a server implementation that doesn't support Note that a server implementation that doesn't support
any remote mailboxes is compliant with this specification any remote mailboxes is compliant with this specification
as long as it accepts and ignores the REMOTE selection option. as long as it accepts and ignores the REMOTE selection option.
MATCHPARENT - when this option is specified, the "\Placeholder" MATCHPARENT - when this option is specified, the "\Placeholder"
and the "\HasSubmailboxes" attributes MUST be accurate (see their and the "\HasSubMailboxes" attributes MUST be accurate (see their
description above). This might force the server to return description above). This might force the server to return
information about parent mailboxes that don't match other information about parent mailboxes that don't match other
selection options, but have some submailboxes that do. selection options, but have some submailboxes that do.
Note 1: In order for a parent mailbox to be returned, it still Note 1: In order for a parent mailbox to be returned, it still
has to match the canonical LIST pattern. has to match the canonical LIST pattern.
Note 2: When calculating "\Placeholder"/"\HasSubmailboxes" Note 2: When calculating "\Placeholder"/"\HasSubMailboxes"
attributes, it doesn't matter if the submailbox matches attributes, it doesn't matter if the submailbox matches
the canonical LIST pattern or not. See also example 9 in the canonical LIST pattern or not. See also example 9 in
section 5. section 5.
The MATCHPARENT option MUST NOT occur as the only selection option, The MATCHPARENT option MUST NOT occur as the only selection option,
as it only makes sense when other selection options are also used. as it only makes sense when other selection options are also used.
The server MUST return BAD tagged response in such case. The server MUST return BAD tagged response in such case.
Note, that even if MATCHPARENT option is specified, the client Note that even if MATCHPARENT option is specified, the client
still MUST be able to handle a case when a "\PlaceHolder"/ MUST still be able to handle a case when a "\PlaceHolder"/
"\HasSubmailboxes" is returned and there are no submailboxes "\HasSubMailboxes" is returned and there are no submailboxes
that meet the selection criteria of the given LIST command, that meet the selection criteria of the given LIST command,
as they can be deleted/renamed after the LIST response was sent, as they can be deleted/renamed after the LIST response was sent,
but before the client had a chance to access them. but before the client had a chance to access them.
The return options defined in this specification are The return options defined in this specification are
SUBSCRIBED - causes the LIST command to return subscription SUBSCRIBED - causes the LIST command to return subscription
state for all matching mailbox names. The "\Subscribed" state for all matching mailbox names. The "\Subscribed"
attribute MUST be supported and MUST be accurately computed attribute MUST be supported and MUST be accurately computed
when the SUBSCRIBED return option is specified. when the SUBSCRIBED return option is specified.
CHILDREN - Requests mailbox child information as originally CHILDREN - Requests mailbox child information as originally
proposed in [ChildMbox]. See section 4, below, for details. proposed in [ChildMbox]. See section 4, below, for details.
This option MUST be accepted by all servers, however it MAY This option MUST be accepted by all servers, however it MAY
be ignored. be ignored.
3.1. General principals for returning LIST responses 3.1. General principles for returning LIST responses
This section outlines several principals that can be used by server This section outlines several principles that can be used by server
implementations of this document to decide if a LIST response should be implementations of this document to decide if a LIST response should be
returned, as well as how many responses and what kind of information returned, as well as how many responses and what kind of information
they may contain. they may contain.
1) Exactly one LIST response should be returned for each mailbox 1) Exactly one LIST response should be returned for each mailbox
name which matches the canonical LIST pattern. name which matches the canonical LIST pattern.
Server implementors must not assume that clients will be able to Server implementors must not assume that clients will be able to
assemble mailbox attributes and other information returned in multiple assemble mailbox attributes and other information returned in multiple
LIST responses. LIST responses.
2) There are only two reasons for including a matching mailbox name 2) There are only two reasons for including a matching mailbox name
in the responses to the LIST command (Note, that the server is allowed in the responses to the LIST command (Note that the server is allowed
to return unsolicited responses at any time. Such responses are not to return unsolicited responses at any time. Such responses are not
governed by this rule): governed by this rule):
a) the mailbox name also satisfies the selection criteria; a) the mailbox name also satisfies the selection criteria;
b) the mailbox name has at least one child mailbox that satisfies b) the mailbox name doesn't satisfy the selection criteria, but
the selection criteria, but doesn't match the canonical LIST it has at least one child mailbox name that satisfies the
pattern. For more information on this case see the \PlaceHolder selection criteria and that doesn't match the canonical LIST
attribute description in Section 3. pattern.
For more information on this case see the \PlaceHolder
attribute description in Section 3. Note that the "\Placeholder"
attribute can only be returned when the MATCHPARENT selection
option is specified.
3) Attributes returned in the same LIST response must be treated additively. 3) Attributes returned in the same LIST response must be treated additively.
For example the following response For example the following response
S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach"
means that the "Fruit/Peach" mailbox doesn't exist, but it is means that the "Fruit/Peach" mailbox doesn't exist, but it is
subscribed. subscribed.
3.2. Additional requirements on LISTEXT clients 3.2. Additional requirements on LISTEXT clients
skipping to change at line 383 skipping to change at line 409
For example, the client must treat presence of the \NoInferiors attribute For example, the client must treat presence of the \NoInferiors attribute
as if the \HasNoChildren attribute was also sent by the server. as if the \HasNoChildren attribute was also sent by the server.
The following table summarizes inference rules described in section 3. The following table summarizes inference rules described in section 3.
+--------------------+-------------------+ +--------------------+-------------------+
| returned attribute | implied attribute | | returned attribute | implied attribute |
+--------------------+-------------------+ +--------------------+-------------------+
| \NoInferiors | \HasNoChildren | | \NoInferiors | \HasNoChildren |
| \Placeholder | \HasChildren |
| \HasSubmailboxes | \HasChildren |
| \NonExistent | \NoSelect | | \NonExistent | \NoSelect |
+--------------------+-------------------+ +--------------------+-------------------+
4. The CHILDREN return Option 4. The CHILDREN return Option
The CHILDREN return option implements the Child Mailbox Extension, The CHILDREN return option implements the Child Mailbox Extension,
originally proposed by Mike Gahrns and Raymond Cheng, of Microsoft originally proposed by Mike Gahrns and Raymond Cheng, of Microsoft
Corporation. Most of the information in this section is taken Corporation. Most of the information in this section is taken
directly from their original specification [ChildMbox]. The CHILDREN directly from their original specification [ChildMbox]. The CHILDREN
return option is simply an indication that the client wants this return option is simply an indication that the client wants this
skipping to change at line 455 skipping to change at line 479
selection option, and they will simply ignore the CHILDREN return option selection option, and they will simply ignore the CHILDREN return option
if both are requested. It is an error for the server to return both a if both are requested. It is an error for the server to return both a
\HasChildren and a \HasNoChildren attribute in a LIST response. \HasChildren and a \HasNoChildren attribute in a LIST response.
Note: the \HasNoChildren attribute should not be confused with the Note: the \HasNoChildren attribute should not be confused with the
IMAP4 [IMAP4] defined attribute \NoInferiors which indicates that no IMAP4 [IMAP4] defined attribute \NoInferiors which indicates that no
child mailboxes exist now and none can be created in the future. child mailboxes exist now and none can be created in the future.
5. Examples 5. Examples
Example 1:
The first example shows the complete local hierarchy that will be The first example shows the complete local hierarchy that will be
used for the other examples. used for the other examples.
Example 1:
C: A01 LIST "" "*" C: A01 LIST "" "*"
S: * LIST (\Marked \NoInferiors) "/" "inbox" S: * LIST (\Marked \NoInferiors) "/" "inbox"
S: * LIST () "/" "Fruit" S: * LIST () "/" "Fruit"
S: * LIST () "/" "Fruit/Apple" S: * LIST () "/" "Fruit/Apple"
S: * LIST () "/" "Fruit/Banana" S: * LIST () "/" "Fruit/Banana"
S: * LIST () "/" "Tofu" S: * LIST () "/" "Tofu"
S: * LIST () "/" "Vegetable" S: * LIST () "/" "Vegetable"
S: * LIST () "/" "Vegetable/Broccoli" S: * LIST () "/" "Vegetable/Broccoli"
S: * LIST () "/" "Vegetable/Corn" S: * LIST () "/" "Vegetable/Corn"
S: A01 OK done S: A01 OK done
Example 2:
In the next example, we'll see the subscribed mailboxes. This is In the next example, we'll see the subscribed mailboxes. This is
similar, but not equivalent, to <LSUB "" "*">. Note that the mailbox similar to, but not equivalent with, <LSUB "" "*">. Note that the mailbox
called "Fruit/Peach" is subscribed to, but does not actually exist called "Fruit/Peach" is subscribed to, but does not actually exist
(perhaps it was deleted while still subscribed). The "Fruit" (perhaps it was deleted while still subscribed). The "Fruit"
mailbox is not subscribed to, but it has two subscribed children. mailbox is not subscribed to, but it has two subscribed children.
The "Vegetable" mailbox is subscribed and has two children, one The "Vegetable" mailbox is subscribed and has two children, one
of them is subscribed as well. of them is subscribed as well.
Example 2:
C: A02 LIST (SUBSCRIBED) "" "*" C: A02 LIST (SUBSCRIBED) "" "*"
S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox"
S: * LIST (\PlaceHolder) "/" "Fruit"
S: * LIST (\Subscribed) "/" "Fruit/Banana" S: * LIST (\Subscribed) "/" "Fruit/Banana"
S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach"
S: * LIST (\Subscribed \HasSubmailboxes) "/" "Vegetable"
S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" S: * LIST (\Subscribed) "/" "Vegetable/Broccoli"
S: A02 OK done S: A02 OK done
Example 3:
The next example shows the use of the CHILDREN option. The client, The next example shows the use of the CHILDREN option. The client,
without having to list the second level of hierarchy, now knows which without having to list the second level of hierarchy, now knows which
of the top-level mailboxes have sub-mailboxes (children) and which do of the top-level mailboxes have submailboxes (children) and which do
not. Note that it's not necessary for the server to return the not. Note that it's not necessary for the server to return the
\HasNoChildren attribute for the inbox, because the \NoInferiors attribute \HasNoChildren attribute for the inbox, because the \NoInferiors attribute
already implies that, and has a stronger meaning. already implies that, and has a stronger meaning.
Example 3:
C: A03 LIST () "" "%" RETURN (CHILDREN) C: A03 LIST () "" "%" RETURN (CHILDREN)
S: * LIST (\Marked \NoInferiors) "/" "inbox" S: * LIST (\Marked \NoInferiors) "/" "inbox"
S: * LIST (\HasChildren) "/" "Fruit" S: * LIST (\HasChildren) "/" "Fruit"
S: * LIST (\HasNoChildren) "/" "Tofu" S: * LIST (\HasNoChildren) "/" "Tofu"
S: * LIST (\HasChildren) "/" "Vegetable" S: * LIST (\HasChildren) "/" "Vegetable"
S: A03 OK done S: A03 OK done
Example 4:
In this example we see more mailboxes, which reside on another server In this example we see more mailboxes, which reside on another server
to which we may obtain referrals. This is similar to the command to which we may obtain referrals. This is similar to the command
<RLIST "" "%">. Note that in the case of the remote mailboxes, the <RLIST "" "%">. Note that in the case of the remote mailboxes, the
server might or might not be able to include CHILDREN information; server might or might not be able to include CHILDREN information;
it includes it if it can, and omits it if it can't. it includes it if it can, and omits it if it can't.
Example 4:
C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN)
S: * LIST (\Marked \NoInferiors) "/" "inbox" S: * LIST (\Marked \NoInferiors) "/" "inbox"
S: * LIST (\HasChildren) "/" "Fruit" S: * LIST (\HasChildren) "/" "Fruit"
S: * LIST (\HasNoChildren) "/" "Tofu" S: * LIST (\HasNoChildren) "/" "Tofu"
S: * LIST (\HasChildren) "/" "Vegetable" S: * LIST (\HasChildren) "/" "Vegetable"
S: * LIST (\Remote) "/" "Bread" S: * LIST (\Remote) "/" "Bread"
S: * LIST (\HasChildren \Remote) "/" "Meat" S: * LIST (\HasChildren \Remote) "/" "Meat"
S: A04 OK done S: A04 OK done
Example 5:
The following example also requests the server to include mailboxes, The following example also requests the server to include mailboxes,
which reside on another server. The server returns information about which reside on another server. The server returns information about
all mailboxes which are subscribed. This is similar to the command all mailboxes which are subscribed. This is similar to the command
<RLSUB "" "%">. We also see the mixing of two selection options. <RLSUB "" "%">. We also see the use of two selection options.
Example 5:
C: A05 LIST (REMOTE SUBSCRIBED) "" "*" C: A05 LIST (REMOTE SUBSCRIBED) "" "*"
S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox"
S: * LIST (\Subscribed) "/" "Fruit/Banana" S: * LIST (\Subscribed) "/" "Fruit/Banana"
S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach"
S: * LIST (\Subscribed) "/" "Vegetable" S: * LIST (\Subscribed) "/" "Vegetable"
S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" S: * LIST (\Subscribed) "/" "Vegetable/Broccoli"
S: * LIST (\Remote \Subscribed) "/" "Bread" S: * LIST (\Remote \Subscribed) "/" "Bread"
S: A05 OK done S: A05 OK done
Example 6:
The following example requests the server to include mailboxes, The following example requests the server to include mailboxes,
which reside on another server. The server is requested to return which reside on another server. The server is requested to return
subscription information for all returned mailboxes. This is different subscription information for all returned mailboxes. This is different
from the example above. from the example above.
Note, that the output of this command is not a superset of the output Note that the output of this command is not a superset of the output
in the previous example, as it doesn't include LIST response for the in the previous example, as it doesn't include LIST response for the
non-existent "Fruit/Peach". non-existent "Fruit/Peach".
Example 6:
C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED)
S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox"
S: * LIST () "/" "Fruit" S: * LIST () "/" "Fruit"
S: * LIST () "/" "Fruit/Apple" S: * LIST () "/" "Fruit/Apple"
S: * LIST (\Subscribed) "/" "Fruit/Banana" S: * LIST (\Subscribed) "/" "Fruit/Banana"
S: * LIST () "/" "Tofu" S: * LIST () "/" "Tofu"
S: * LIST (\Subscribed) "/" "Vegetable" S: * LIST (\Subscribed) "/" "Vegetable"
S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" S: * LIST (\Subscribed) "/" "Vegetable/Broccoli"
S: * LIST () "/" "Vegetable/Corn" S: * LIST () "/" "Vegetable/Corn"
S: * LIST (\Remote \Subscribed) "/" "Bread" S: * LIST (\Remote \Subscribed) "/" "Bread"
S: * LIST (\Remote) "/" "Meat" S: * LIST (\Remote) "/" "Meat"
S: A06 OK done S: A06 OK done
Example 7:
In the following example the client has specified multiple mailbox In the following example the client has specified multiple mailbox
patterns. Note, that this example doesn't use the mailbox hierarchy patterns. Note that this example doesn't use the mailbox hierarchy
used in the previous examples. used in the previous examples.
Example 7:
C: BBB LIST "" ("INBOX" "Drafts" "Sent/%") C: BBB LIST "" ("INBOX" "Drafts" "Sent/%")
S: * LIST () "/" "INBOX" S: * LIST () "/" "INBOX"
S: * LIST (\NoInferiors) "/" "Drafts" S: * LIST (\NoInferiors) "/" "Drafts"
S: * LIST () "/" "Sent/March2004" S: * LIST () "/" "Sent/March2004"
S: * LIST (\Marked) "/" "Sent/December2003" S: * LIST (\Marked) "/" "Sent/December2003"
S: * LIST () "/" "Sent/August2004" S: * LIST () "/" "Sent/August2004"
S: BBB OK done S: BBB OK done
The following example demonstates the difference between \HasChildren
and \PlaceHolder/\SubMailboxes.
Example 8: Example 8:
The following example demonstates the difference between
\HasChildren and \PlaceHolder/\SubMailboxes.
Let's assume there is the following hierarchy: Let's assume there is the following hierarchy:
C: C01 LIST "" "*" C: C01 LIST "" "*"
S: * LIST (\Marked \NoInferiors) "/" "inbox" S: * LIST (\Marked \NoInferiors) "/" "inbox"
S: * LIST () "/" "Foo" S: * LIST () "/" "Foo"
S: * LIST () "/" "Foo/Bar" S: * LIST () "/" "Foo/Bar"
S: * LIST () "/" "Foo/Baz" S: * LIST () "/" "Foo/Baz"
S: * LIST () "/" "Moo" S: * LIST () "/" "Moo"
S: C01 OK done S: C01 OK done
If the client asks RETURN (CHILDREN) it will get: If the client asks RETURN (CHILDREN) it will get:
C: CA3 LIST "" "%" RETURN (CHILDREN) C: CA3 LIST "" "%" RETURN (CHILDREN)
S: * LIST (\Marked \NoInferiors) "/" "inbox" S: * LIST (\Marked \NoInferiors) "/" "inbox"
S: * LIST (\HasChildren) "/" "Foo" S: * LIST (\HasChildren) "/" "Foo"
S: * LIST (\HasNoChildren) "/" "Moo" S: * LIST (\HasNoChildren) "/" "Moo"
S: CA3 OK done S: CA3 OK done
A). Let's also assume that the mailbox "Foo/Baz" is the only subscribed A). Let's also assume that the mailbox "Foo/Baz" is the only
mailbox. Then subscribed mailbox. Then
C: C02 LIST (SUBSCRIBED) "" "*" C: C02 LIST (SUBSCRIBED) "" "*"
S: * LIST (\Subscribed) "/" "Foo/Baz" S: * LIST (\Subscribed) "/" "Foo/Baz"
S: C02 OK done S: C02 OK done
Now, if the client issues <LIST (SUBSCRIBED) "" "%">, the server will Now, if the client issues <LIST (SUBSCRIBED) "" "%">, the server will
return no mailboxes (as the mailboxes "Moo", "Foo" and "Inbox" are NOT return no mailboxes (as the mailboxes "Moo", "Foo" and "Inbox" are NOT
subscribed). However, if the client issues: subscribed). However, if the client issues:
C: C04 LIST (SUBSCRIBED MATCHPARENT) "" "%" C: C04 LIST (SUBSCRIBED MATCHPARENT) "" "%"
S: * LIST (\PlaceHolder) "/" "Foo" S: * LIST (\PlaceHolder) "/" "Foo"
S: C04 OK done S: C04 OK done
i.e. the mailbox "Foo" is not subscribed, but it has a child that is. i.e. the mailbox "Foo" is not subscribed, but it has a child that is.
A1). If the mailbox "Foo" would have been subscribed instead, the last A1). If the mailbox "Foo" would have been subscribed instead, the last
command would return: command would return:
S: * LIST (\HasSubmailboxes \Subscribed) "/" "Foo" S: * LIST (\HasSubMailboxes \Subscribed) "/" "Foo"
or even or even
S: * LIST (\HasSubmailboxes \HasChildren \Subscribed) "/" "Foo" S: * LIST (\HasSubMailboxes \HasChildren \Subscribed) "/" "Foo"
(Both \HasSubmailboxes and \PlaceHolder imply \HasChildren, so the latter
doesn't have to be returned)
A2). If we assume instead that the mailbox "Foo" is not part of the A2). If we assume instead that the mailbox "Foo" is not part of the
original hierarchy and is not subscribed, the last command will original hierarchy and is not subscribed, the last command will
return return
S: * LIST (\PlaceHolder \NonExistent) "/" "Foo" S: * LIST (\PlaceHolder \NonExistent) "/" "Foo"
B). Now, let's assume that no mailbox is subscribed. In this case B). Now, let's assume that no mailbox is subscribed. In this case
the command <LIST (SUBSCRIBED MATCHPARENT) "" "%"> will return the command <LIST (SUBSCRIBED MATCHPARENT) "" "%"> will return
no responses, as there are no subscribed children (although there no responses, as there are no subscribed children (even though
"Foo" has children). "Foo" has children).
C). And finally, let's assume that the mailboxes "Foo" and "Moo" are C). And finally, let's assume that the mailboxes "Foo" and "Moo" are
subscribed. In this case the command: subscribed. In this case the command:
LIST (SUBSCRIBED MATCHPARENT) "" "%" RETURN (CHILDREN) C: LIST (SUBSCRIBED MATCHPARENT) "" "%" RETURN (CHILDREN)
will return: will return:
S: * LIST (\HasChildren \Subscribed) "/" "Foo" S: * LIST (\HasChildren \Subscribed) "/" "Foo"
S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" S: * LIST (\HasNoChildren \Subscribed) "/" "Moo"
Which means that the mailbox "Foo" has children, but none of them Which means that the mailbox "Foo" has children, but none of them
is subscribed. is subscribed.
The following example demonstrates the calculation of \PlaceHolder
(or \SubMailboxes) attributes is not affected by the fact that children
mailboxes match the canonical LIST pattern.
Example 9: Example 9:
The following example demonstrates that the calculation of \PlaceHolder
(or \HasSubMailboxes) attributes is not affected by the fact that
children mailboxes match the canonical LIST pattern.
Let's assume there is the following hierarchy: Let's assume there is the following hierarchy:
C: D01 LIST "" "*" C: D01 LIST "" "*"
S: * LIST (\Marked \NoInferiors) "/" "inbox" S: * LIST (\Marked \NoInferiors) "/" "inbox"
S: * LIST () "/" "foo2" S: * LIST () "/" "foo2"
S: * LIST () "/" "foo2/bar1" S: * LIST () "/" "foo2/bar1"
S: * LIST () "/" "foo2/bar2" S: * LIST () "/" "foo2/bar2"
S: * LIST () "/" "baz2" S: * LIST () "/" "baz2"
S: * LIST () "/" "baz2/bar2" S: * LIST () "/" "baz2/bar2"
S: * LIST () "/" "baz2/bar22" S: * LIST () "/" "baz2/bar22"
skipping to change at line 697 skipping to change at line 716
The client issues the following command first: The client issues the following command first:
C: D03 LIST (MATCHPARENT SUBSCRIBED) "" "*2" C: D03 LIST (MATCHPARENT SUBSCRIBED) "" "*2"
S: * LIST (\PlaceHolder) "/" "foo2" S: * LIST (\PlaceHolder) "/" "foo2"
S: * LIST (\Subscribed) "/" "foo2/bar2" S: * LIST (\Subscribed) "/" "foo2/bar2"
S: * LIST (\PlaceHolder) "/" "baz2" S: * LIST (\PlaceHolder) "/" "baz2"
S: * LIST (\Subscribed) "/" "baz2/bar2" S: * LIST (\Subscribed) "/" "baz2/bar2"
S: * LIST (\Subscribed) "/" "baz2/bar22" S: * LIST (\Subscribed) "/" "baz2/bar22"
S: * LIST (\Subscribed) "/" "baz2/bar222" S: * LIST (\Subscribed) "/" "baz2/bar222"
S: * LIST (\HasSubmailboxes) "/" "eps2" S: * LIST (\HasSubMailboxes \Subscribed) "/" "eps2"
S: * LIST (\Subscribed) "/" "quux2/bar2" S: * LIST (\Subscribed) "/" "quux2/bar2"
S: D03 OK done S: D03 OK done
and the server may also include and the server may also include
S: * LIST (\PlaceHolder \NonExistent) "/" "quux2" S: * LIST (\PlaceHolder \NonExistent) "/" "quux2"
The \PlaceHolder attribute is returned for mailboxes "foo2" and The \PlaceHolder attribute is returned for mailboxes "foo2" and
"baz2" (and the \HasSubmailboxes is returned for the mailbox "eps2"), "baz2" (and the \HasSubMailboxes is returned for the mailbox "eps2"),
because all of them have subscribed children, because all of them have subscribed children,
even though for the mailbox "foo2" only one of the two subscribed even though for the mailbox "foo2" only one of the two subscribed
children match the pattern, for the mailbox "baz2" all the subscribed children match the pattern, for the mailbox "baz2" all the subscribed
children match the pattern and for the mailbox "eps2" none of the children match the pattern and for the mailbox "eps2" none of the
subscribed children match the pattern. subscribed children match the pattern.
Note, that if the client issues Note that if the client issues
C: D03 LIST (MATCHPARENT SUBSCRIBED) "" "*" C: D03 LIST (MATCHPARENT SUBSCRIBED) "" "*"
S: * LIST (\PlaceHolder) "/" "foo2" S: * LIST (\PlaceHolder) "/" "foo2"
S: * LIST (\Subscribed) "/" "foo2/bar1" S: * LIST (\Subscribed) "/" "foo2/bar1"
S: * LIST (\Subscribed) "/" "foo2/bar2" S: * LIST (\Subscribed) "/" "foo2/bar2"
S: * LIST (\PlaceHolder) "/" "baz2" S: * LIST (\PlaceHolder) "/" "baz2"
S: * LIST (\Subscribed) "/" "baz2/bar2" S: * LIST (\Subscribed) "/" "baz2/bar2"
S: * LIST (\Subscribed) "/" "baz2/bar22" S: * LIST (\Subscribed) "/" "baz2/bar22"
S: * LIST (\Subscribed) "/" "baz2/bar222" S: * LIST (\Subscribed) "/" "baz2/bar222"
S: * LIST (\HasSubmailboxes) "/" "eps2" S: * LIST (\HasSubMailboxes \Subscribed) "/" "eps2"
S: * LIST (\Subscribed) "/" "eps2/mamba" S: * LIST (\Subscribed) "/" "eps2/mamba"
S: * LIST (\Subscribed) "/" "quux2/bar2" S: * LIST (\Subscribed) "/" "quux2/bar2"
S: D03 OK done S: D03 OK done
the mailboxes "foo2", "baz2" and "eps2" still have the same the mailboxes "foo2", "baz2" and "eps2" still have the same
\PlaceHolder/\HasSubmailboxes attribute, even though this information \PlaceHolder/\HasSubMailboxes attribute, even though this information
is redundant and the client can determine it by itself. is redundant and the client can determine it by itself.
Example 10:
The following example shows usage of multiple mailbox patterns.
It also demonstrates that \HasSubmailboxes/\PlaceHolder attributes
don't necessarily imply \HasChildren.
C: a1 LIST "" ("foo" "foo/*")
S: * LIST () "/" foo
S: a1 OK done
C: a2 LIST (SUBSCRIBED) "" "foo/*"
S: * LIST (\Subscribed \NonExistent) "/" foo/bar
S: a2 OK done
C: a3 LIST (SUBSCRIBED MATCHPARENT) "" foo RETURN (CHILDREN)
S: * LIST (\Placeholder \HasNoChildren) "/" foo
S: a3 OK done
6. Formal Syntax 6. Formal Syntax
The following syntax specification uses the augmented Backus-Naur The following syntax specification uses the augmented Backus-Naur
Form (BNF) as described in [ABNF]. Terms not defined here are taken Form (BNF) as described in [ABNF]. Terms not defined here are taken
from [IMAP4]. "vendor-token" is defined in [ACAP]. from [IMAP4]. "vendor-token" is defined in [ACAP].
child-mbox-flag = "\HasChildren" / "\HasNoChildren" child-mbox-flag = "\HasChildren" / "\HasNoChildren"
; attributes for CHILDREN return option, at most one ; attributes for CHILDREN return option, at most one
; possible per LIST response ; possible per LIST response
list = "LIST" [SP list-select-opts] SP mailbox SP mbox_or_pat list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat
[SP list-return-opts] [SP list-return-opts]
list-select-opts = "(" [list-select-option *(SP list-select-option)] ")" list-select-opts = "(" [*(list-select-mod-opt SP) list-select-base-opt
*(SP list-select-opt)] ")"
; list selection options, e.g. REMOTE ; list selection options, e.g. REMOTE
list-return-opts = "RETURN" SP "(" [return-option *(SP return-option)] ")" list-return-opts = "RETURN" SP "(" [return-option *(SP return-option)] ")"
; list return options, e.g. CHILDREN ; list return options, e.g. CHILDREN
mparent-mbox-flag = "\PlaceHolder" / "\HasSubmailboxes" mparent-mbox-flag = "\PlaceHolder" / "\HasSubMailboxes"
; attributes for MATCHPARENT selection option, ; attributes for MATCHPARENT selection option,
; at most one possible per LIST response ; at most one possible per LIST response
mailbox-list = "(" [mbx-list-flags] ")" SP mailbox-list = "(" [mbx-list-flags] ")" SP
(DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox
[SP mbox-list-extended] [SP mbox-list-extended]
mbox-list-extended = "(" [mbox-list-extended-item mbox-list-extended = "(" [mbox-list-extended-item
*(SP mbox-list-extended-item)] ")" *(SP mbox-list-extended-item)] ")"
mbox-list-extended-item = "(" mbox-list-extended-item-data ")" mbox-list-extended-item = "(" mbox-list-extended-item-data ")"
mbox-list-extended-item-data = mbox-list-extended-item-tag SP nstring-list mbox-list-extended-item-data = mbox-list-extended-item-tag SP nstring-list
mbox-list-extended-item-tag = astring mbox-list-extended-item-tag = astring
; The content MUST conform to either "eitem-vendor-tag" or ; The content MUST conform to either "eitem-vendor-tag" or
; "eitem-standard-tag" ABNF productions. ; "eitem-standard-tag" ABNF productions.
; A tag registration template is described in section ; A tag registration template is described in section
; 8.5 of this document. ; 8.5 of this document.
mbox_or_pat = list-mailbox / patterns mbox-or-pat = list-mailbox / patterns
patterns = "(" list-mailbox *(list-mailbox) ")" patterns = "(" list-mailbox *(SP list-mailbox) ")"
eitem-vendor-tag = vendor-tag eitem-vendor-tag = vendor-tag
; a vendor specific tag for extended list data ; a vendor specific tag for extended list data
eitem-standard-tag = atom eitem-standard-tag = atom
; a tag for extended list data defined in a Standard ; a tag for extended list data defined in a Standard
; Track or Experimental RFC. ; Track or Experimental RFC.
nstring-list = nstring / nstring-list = nstring /
"(" [nstring-list *(SP nstring-list)] ")" "(" [nstring-list *(SP nstring-list)] ")"
;; a recursive list definition ;; a recursive list definition
mbox-list-oflag = child-mbox-flag / mparent-mbox-flag / "\NonExistent" / mbox-list-oflag = child-mbox-flag / mparent-mbox-flag / "\NonExistent" /
/ "\Subscribed" / "\Remote" / "\Subscribed" / "\Remote"
list-select-option = "SUBSCRIBED" / "REMOTE" / "MATCHPARENT" / list-select-opt = list-sel-mod-opt / list-sel-base-opt
option-extension
; An option registration template is described in ; An option registration template is described in
; section 8.3 of this document. ; section 8.3 of this document.
list-sel-base-opt = "SUBSCRIBED" / "REMOTE" / option-extension
; options that can be used by themselves
list-sel-mod-opt = "MATCHPARENT" / option-extension
; options that require a list-select-base-opt
; to also be present
return-option = "SUBSCRIBED" / "CHILDREN" / return-option = "SUBSCRIBED" / "CHILDREN" /
option-extension option-extension
option-extension = option-vendor-tag / option-standard-tag option-extension = option-vendor-tag / option-standard-tag
option-vendor-tag = vendor-tag option-vendor-tag = vendor-tag
; a vendor specific option ; a vendor specific option
option-standard-tag= atom option-standard-tag= atom
; an option defined in a Standard Track or ; an option defined in a Standard Track or
skipping to change at line 1020 skipping to change at line 1064
To: iana@iana.org To: iana@iana.org
Subject: Registration of LISTEXT option MATCHPARENT Subject: Registration of LISTEXT option MATCHPARENT
LISTEXT option name: MATCHPARENT LISTEXT option name: MATCHPARENT
LISTEXT option type: SELECTION LISTEXT option type: SELECTION
Implied return options(s): (none) Implied return options(s): (none)
LISTEXT option description: Requests that \Placeholder/ LISTEXT option description: Requests that \Placeholder/
\HasSubmailboxes attributes are to be accurately computed. \HasSubMailboxes attributes are to be returned.
Published specification : this RFC, sections 3. Published specification : this RFC, sections 3.
Published specification : this RFC Published specification : this RFC
Security considerations: this RFC, section 7. Security considerations: this RFC, section 7.
Intended usage: COMMON Intended usage: COMMON
Person & email address to contact for further information: Person & email address to contact for further information:
 End of changes. 

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