draft-ietf-extra-sieve-special-use-04.txt   draft-ietf-extra-sieve-special-use-05.txt 
EXTRA S. Bosch EXTRA S. Bosch
Internet-Draft Dovecot Oy Internet-Draft Open Xchange Oy
Intended status: Standards Track November 27, 2018 Intended status: Standards Track January 25, 2019
Expires: May 31, 2019 Expires: July 29, 2019
Sieve Email Filtering: Delivering to Special-Use Mailboxes Sieve Email Filtering: Delivering to Special-Use Mailboxes
draft-ietf-extra-sieve-special-use-04 draft-ietf-extra-sieve-special-use-05
Abstract Abstract
The SPECIAL-USE capability of the IMAP protocol (RFC 6154) allows The SPECIAL-USE capability of the IMAP protocol (RFC 6154) allows
clients to identify special-use mailboxes; e.g., where draft or sent clients to identify special-use mailboxes; e.g., where draft or sent
messages should be put. This simplifies client configuration. In messages should be put. This simplifies client configuration. In
contrast, the Sieve mail filtering language (RFC 5228) currently has contrast, the Sieve mail filtering language (RFC 5228) currently has
no such capability. This memo defines a Sieve extension that fills no such capability. This memo defines a Sieve extension that fills
this gap: it adds a test for checking whether a special-use attribute this gap: it adds a test for checking whether a special-use attribute
is assigned for a particular mailbox or any mailbox, and it adds the is assigned for a particular mailbox or any mailbox, and it adds the
ability to file messages into an anonymous mailbox that has a ability to file messages into a mailbox identified solely by a
particular special-use attribute assigned. special-use attribute.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 31, 2019. This Internet-Draft will expire on July 29, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 2, line 31 skipping to change at page 2, line 31
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 10 10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 11 10.2. Informative References . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
Commonly, several mailboxes in an IMAP message store [IMAP] have a Commonly, several mailboxes in an IMAP message store [IMAP] have a
special use; e.g. it is where the user's draft messages are stored, special use. For example, there can be a special-use mailbox for
where a copy of sent messages are kept, or it is where spam messages storing the user's draft messages, for keeping copies of sent
are filed automatically at delivery. The SPECIAL-USE capability messages, and for collecting spam messages that were classified as
[SPECIAL-USE] of the IMAP protocol defines mailbox attributes that such at delivery. The SPECIAL-USE capability [SPECIAL-USE] of the
identify these special mailboxes explicitly to the client. This way, IMAP protocol defines mailbox attributes that identify these special
client configuration is simplified significantly. Using the CREATE- mailboxes explicitly to the client. This way, client configuration
SPECIAL-USE capability [SPECIAL-USE], IMAP clients can also configure is simplified significantly. Using the CREATE-SPECIAL-USE capability
these attributes dynamically based on user preference. [SPECIAL-USE], IMAP clients can also configure these attributes
dynamically based on user preference.
Unlike the IMAP protocol, the Sieve mail filtering language [SIEVE] Unlike the IMAP protocol, the Sieve mail filtering language [SIEVE]
currently cannot freely access these special-use mailbox attributes. currently cannot freely access these special-use mailbox attributes.
Particularly, the Sieve interpreter cannot find an anonymous mailbox Particularly, the Sieve interpreter has no means to identify a
that has a particular special-use attribute assigned. This would be mailbox with a particular special-use attribute. This would be very
very useful for example to find the user's Spam mailbox at delivery. useful for example to find the user's Spam mailbox at delivery.
In Sieve, limited access to the special-use attributes is provided In Sieve, limited access to the special-use attributes is provided
using the "mboxmetadata" extension [SIEVE-MAILBOX], which allows using the "mboxmetadata" extension [SIEVE-MAILBOX], which allows
testing for the presence of a special-use attribute in the "/private/ testing for the presence of a special-use attribute in the "/private/
specialuse" IMAP METADATA [IMAP-METADATA] entry of a mailbox. Still, specialuse" IMAP METADATA [IMAP-METADATA] entry of a mailbox. Still,
not all implementers will be willing to add the complexity of the not all implementers will be willing to add the complexity of the
IMAP METADATA capability, just to provide access to special-use IMAP METADATA capability, just to provide access to special-use
attributes to the Sieve interpreter. attributes to the Sieve interpreter.
This document defines an extension to the Sieve mail filtering This document defines an extension to the Sieve mail filtering
language that adds the ability to freely access mailbox special-use language that adds the ability to freely access mailbox special-use
attributes. It adds a test called "specialuse_exists" that checks attributes. It adds a test called "specialuse_exists" that checks
whether a special-use attribute is assigned for a particular mailbox whether a special-use attribute is assigned for a particular mailbox
or - if omitted - any of the user's personal mailboxes. It also adds or - if omitted - any of the user's personal mailboxes. It also adds
the ability to file messages into an anonymous personal mailbox that the ability to file messages into a personal mailbox identified by a
has a particular special-use attribute assigned using a ":specialuse" particular special-use attribute rather than the mailbox's name.
argument for the "fileinto" command [SIEVE]. This is achieved using the new ":specialuse" argument for the
"fileinto" command [SIEVE].
2. Conventions Used in This Document 2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in [KEYWORDS]. "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [KEYWORDS] [KEYWORDS-UPD] when, and only when, they appear in
all capitals, as shown here.
Conventions for notations are as in [SIEVE] Section 1.1, including Conventions for notations are as in [SIEVE] Section 1.1, including
use of the "Usage:" label for the definition of action and tagged use of the "Usage:" label for the definition of action and tagged
arguments syntax. arguments syntax.
In [IMAP] examples, "C:" and "S:" indicate lines sent by the client In [IMAP] examples, "C:" and "S:" indicate lines sent by the client
and server respectively. If such lines are wrapped without a new and server respectively. If such lines are wrapped without a new
"C:" or "S:" label, then the wrapping is for editorial clarity and is "C:" or "S:" label, then the wrapping is for editorial clarity and is
not part of the command. not part of the command.
3. Test "specialuse_exists" 3. Test "specialuse_exists"
Usage: specialuse_exists [<mailbox: string>] Usage: specialuse_exists [<mailbox: string>]
<special-use-flags: string-list> <special-use-attrs: string-list>
If the "mailbox" string argument is omitted, the "specialuse_exists" If the "mailbox" string argument is omitted, the "specialuse_exists"
test yields true if all of the following statements are true for each test yields true if all of the following statements are true for each
of the special-use flags listed in the "special-use-flags" argument: of the special-use attributes listed in the "special-use-attrs"
argument:
a. at least one mailbox exists in the user's personal namespace a. at least one mailbox exists in the user's personal namespace
[NAMESPACE] that has that particular special-use flag assigned, [NAMESPACE] that has that particular special-use attribute
and assigned, and
b. that mailbox allows the user in whose context the Sieve script b. that mailbox allows the user in whose context the Sieve script
runs to "deliver" messages into it. runs to "deliver" messages into it.
If the "mailbox" argument is specified, the "specialuse_exists" test If the "mailbox" argument is specified, the "specialuse_exists" test
yields true if all of the following statements are true: yields true if all of the following statements are true:
a. the indicated mailbox exists, a. the indicated mailbox exists,
b. that mailbox allows the user in whose context the Sieve script b. that mailbox allows the user in whose context the Sieve script
runs to "deliver" messages into it, and runs to "deliver" messages into it, and
c. that mailbox has all of the special-use flags listed in the c. that mailbox has all of the special-use attributes listed in the
"special-use-flags" argument assigned to it. "special-use-attrs" argument assigned to it.
Refer to the specification of the "mailboxexists" test in Section 3.1 Refer to the specification of the "mailboxexists" test in Section 3.1
of RFC 5490 [SIEVE-MAILBOX] for a definition of when "delivery" of of RFC 5490 [SIEVE-MAILBOX] for a definition of when "delivery" of
messages into a mailbox is deemed possible. messages into a mailbox is deemed possible.
3.1. Equivalent IMAP Operations 3.1. Equivalent IMAP Operations
To clarify, a sequence of [IMAP] commands that a client could send to To clarify, a sequence of [IMAP] commands that a client could send to
perform an assessment without Sieve that is equivalent to the perform an assessment without Sieve that is equivalent to the
"specialuse_exists" test is shown in the following IMAP protocol "specialuse_exists" test is shown in the following IMAP protocol
skipping to change at page 4, line 30 skipping to change at page 4, line 36
First, the client queries which namespaces are available using the First, the client queries which namespaces are available using the
NAMESPACE command [NAMESPACE]: NAMESPACE command [NAMESPACE]:
C: A01 NAMESPACE C: A01 NAMESPACE
S: * NAMESPACE (("INBOX/" "/")("Archive/" "/")) NIL (("Public/" "/")) S: * NAMESPACE (("INBOX/" "/")("Archive/" "/")) NIL (("Public/" "/"))
S: A01 OK NAMESPACE command completed S: A01 OK NAMESPACE command completed
Subsequently, when no particular mailbox is of interest (i.e., the Subsequently, when no particular mailbox is of interest (i.e., the
"specialuse_exists" test has no mailbox argument), the client lists "specialuse_exists" test has no mailbox argument), the client lists
all mailboxes with special-use flags in the two returned personal all mailboxes with special-use attributes in the two returned
namespaces (this extended LIST command requires the LIST-EXTENDED personal namespaces (this extended LIST command requires the LIST-
IMAP capability [LIST-EXTENDED]): EXTENDED IMAP capability [LIST-EXTENDED]):
C: A02 LIST (SPECIAL-USE) "" ("INBOX/*" "Archive/*") C: A02 LIST (SPECIAL-USE) "" ("INBOX/*" "Archive/*")
RETURN (SPECIAL-USE) RETURN (SPECIAL-USE)
S: * LIST (\Drafts) "/" INBOX/Drafts S: * LIST (\Drafts) "/" INBOX/Drafts
S: * LIST (\Trash) "/" INBOX/Trash S: * LIST (\Trash) "/" INBOX/Trash
S: * LIST (\Sent) "/" INBOX/Sent S: * LIST (\Sent) "/" INBOX/Sent
S: * LIST (\Archive) "/" Archive/Default S: * LIST (\Archive) "/" Archive/Default
S: A02 OK LIST command completed S: A02 OK LIST command completed
Finally, using the MYRIGHTS command [IMAP-ACL], the client determines Finally, using the MYRIGHTS command [IMAP-ACL], the client determines
the access rights it has for the mailbox or mailboxes that have all the access rights it has for the mailbox or mailboxes that have all
the requested flags assigned. This way, it can determine whether the requested attributes assigned. This way, it can determine
messages can be saved to any of those. In this example, an whether messages can be saved to any of those. In this example, an
"\Archive" special-use mailbox is sought: "\Archive" special-use mailbox is sought:
C: A03 MYRIGHTS Archive/Default C: A03 MYRIGHTS Archive/Default
S: * MYRIGHTS Archive/Default lrwsip S: * MYRIGHTS Archive/Default lrwsip
S: A03 OK Myrights completed S: A03 OK Myrights completed
The MYRIGHTS response indicates that the the user has "insert" rights The MYRIGHTS response indicates that the the user has "insert" rights
[IMAP-ACL] for the "Archive/Default" mailbox, meaning that the client [IMAP-ACL] for the "Archive/Default" mailbox, meaning that the client
can deliver (APPEND) messages to that mailbox and that the Sieve can deliver (APPEND) messages to that mailbox and that the Sieve
"specialuse_exists" test would yield "true" in this case. "specialuse_exists" test would yield "true" in this case.
4. ":specialuse" Argument to "fileinto" Command 4. ":specialuse" Argument to "fileinto" Command
Usage: fileinto [:specialuse <special-use-flag: string>] Usage: fileinto [:specialuse <special-use-attr: string>]
<mailbox: string> <mailbox: string>
Normally, the "fileinto" command delivers the message in the mailbox Normally, the "fileinto" command delivers the message in the mailbox
specified using its positional mailbox argument. However, if the specified using its positional mailbox argument, which is the name of
optional ":specialuse" argument is also specified, the "fileinto" the mailbox. However, if the optional ":specialuse" argument is also
command first checks whether a mailbox exists in the user's personal specified, the "fileinto" command first checks whether a mailbox
namespace [NAMESPACE] with the specified special-use flag assigned to exists in the user's personal namespace [NAMESPACE] with the
it. If that is the case, that special-use mailbox is used for specified special-use attribute assigned to it. If that is the case,
delivery instead. If there is no such mailbox or if the specified that special-use mailbox is used for delivery instead. If there is
special-use flag is unknown to the implementation in general, the no such mailbox or if the specified special-use attribute is unknown
"fileinto" action proceeds as it would without the ":specialuse" to the implementation in general, the "fileinto" action proceeds as
argument. it would without the ":specialuse" argument.
Summarizing, if the ":specialuse" argument is specified, the fileinto Summarizing, if the ":specialuse" argument is specified, the fileinto
command deals with two mailboxes that may or may not exist: command deals with two mailboxes that may or may not exist and may in
fact be equal:
o An anonymous special-use mailbox in the user's personal namespace, o A special-use mailbox in the user's personal namespace, which has
which has at least the special-use flag specified with the at least the special-use attribute specified with the
":specialuse" argument assigned to it. ":specialuse" argument assigned to it. The name for this mailbox
is not relevant here: it is only identified by the assigned
special-use attribute.
o The default mailbox named by the positional string argument of the o The default mailbox named by the positional string argument of the
"fileinto" command, which is used when the special-use mailbox is "fileinto" command, which is used when the special-use mailbox is
not found. not found.
The special-use flag specified with the ":specialuse" argument MUST The special-use attribute specified with the ':specialuse' argument
conform to the "use-attr" syntax described in Section 6 of RFC6154 conforms to the 'use-attr' syntax described in Section 6 of RFC6154
[SIEVE-MAILBOX]. Implementations SHOULD handle an invalid special- [SIEVE-MAILBOX]. Implementations SHOULD handle an invalid special-
use flag in the same way as an invalid mailbox name is handled. The use attribute in the same way as an invalid mailbox name is handled.
string parameter of the ":specialuse" argument is not a constant The string parameter of the ":specialuse" argument is not a constant
string, which means that variable substitutions are allowed when the string, which means that variable substitutions are allowed when the
"variables" extension [VARIABLES] is active. In that case, the "variables" extension [VARIABLES] is active. In that case, the
syntax of the special-use flag is only verified at runtime. syntax of the special-use attribute is only verified at runtime.
If neither the special-use mailbox nor the default mailbox exists, If neither the special-use mailbox nor the default mailbox exists,
the "fileinto" action MUST proceed exactly as it does in case the the "fileinto" action MUST proceed exactly as it does in case the
":specialuse" is argument is absent and the mailbox named by its ":specialuse" is argument is absent and the mailbox named by its
positional argument does not exist. The various options for handling positional argument does not exist. The various options for handling
this situation are described in Section 4.1 of RFC5228 [SIEVE]. this situation are described in Section 4.1 of RFC5228 [SIEVE].
More than one mailbox in the user's personal namespace can have a More than one mailbox in the user's personal namespace can have a
particular special-use flag assigned. If one of those mailboxes is particular special-use attribute assigned. If one of those mailboxes
in fact the default mailbox named by the positional string argument is in fact the default mailbox named by the positional string
of the "fileinto" command, that mailbox MUST be used for delivery. argument of the "fileinto" command, that mailbox MUST be used for
If the default mailbox is not one of the options, the mailbox that is delivery. If the default mailbox is not one of the options, the
chosen for delivery is implementation-defined. However, while the mailbox that is chosen for delivery is implementation-defined.
set of mailboxes to which the involved special-use flags are assigned However, while the set of mailboxes to which the involved special-use
remains unchanged, implementations SHOULD ensure that the mailbox attribute are assigned remains unchanged, implementations SHOULD
choice is made consistently, so that the same mailbox is used every ensure that the mailbox choice is made consistently, so that the same
time. Conversely, the chosen mailbox MAY change once the special-use mailbox is used every time. Conversely, the chosen mailbox MAY
flag assignments that are relevant for the mailbox choice are changed change once the special-use attribute assignments that are relevant
(usually by user interaction). for the mailbox choice are changed (usually by user interaction).
If delivery to the special-use mailbox fails for reasons not relating If delivery to the special-use mailbox fails for reasons not relating
to its existence, the Sieve interpreter MUST NOT subsequently attempt to its existence, the Sieve interpreter MUST NOT subsequently attempt
delivery in the indicated default mailbox as a fall-back. Instead, delivery in the indicated default mailbox as a fall-back. Instead,
it MUST proceed exactly as it does in case the ":specialuse" argument it MUST proceed exactly as it does in case the ":specialuse" argument
is absent and delivery to the mailbox named by its positional is absent and delivery to the mailbox named by its positional
argument fails. This prevents the situation where messages are argument fails. This prevents the situation where messages are
unexpectedly spread over two mailboxes in case transient or unexpectedly spread over two mailboxes in case transient or
intermittent delivery failures occur. intermittent delivery failures occur.
skipping to change at page 6, line 47 skipping to change at page 7, line 4
argument has no effect when the implicit creation of mailboxes for argument has no effect when the implicit creation of mailboxes for
delivery is the default behavior. delivery is the default behavior.
When the ":specialuse" argument is present, this behavior does not When the ":specialuse" argument is present, this behavior does not
change: the Sieve interpreter will implicitly create the specified change: the Sieve interpreter will implicitly create the specified
default mailbox if needed. This need arises when both the special- default mailbox if needed. This need arises when both the special-
use mailbox and the default mailbox are not found. use mailbox and the default mailbox are not found.
If the server implementation supports the CREATE-SPECIAL-USE If the server implementation supports the CREATE-SPECIAL-USE
capability [SPECIAL-USE] for IMAP (i.e., it allows assigning special- capability [SPECIAL-USE] for IMAP (i.e., it allows assigning special-
use flags to new mailboxes) it SHOULD assign the special-use flag use attributes to new mailboxes) it SHOULD assign the special-use
specified with the ":specialuse" argument to the newly created attribute specified with the ":specialuse" argument to the newly
mailbox. created mailbox.
4.2. Equivalent IMAP Operations 4.2. Equivalent IMAP Operations
To clarify, a sequence of [IMAP] commands that a client could send to To clarify, a sequence of [IMAP] commands that a client could send to
perform an action without Sieve that is equivalent to the "fileinto" perform an action without Sieve that is equivalent to the "fileinto"
action with the ":specialuse" argument is shown in the following IMAP action with the ":specialuse" argument is shown in the following IMAP
protocol examples. The following Sieve script is assumed: protocol examples. The following Sieve script is assumed:
require "fileinto"; require "fileinto";
require "special-use"; require "special-use";
fileinto :specialuse "\\Archive" "INBOX/Archive"; fileinto :specialuse "\\Archive" "INBOX/Archive";
First, the client proceeds as in Section 3.1 to find out whether the First, the client proceeds as in Section 3.1 to find out whether the
indicated special-use flag is assigned to any mailbox in the user's indicated special-use attribute is assigned to any mailbox in the
personal namespace. If a matching special-use mailbox is found, the user's personal namespace. If a matching special-use mailbox is
message is delivered there using the IMAP APPEND command. If no found, the message is delivered there using the IMAP APPEND command.
matching special-use mailbox is found, the client attempts to deliver If no matching special-use mailbox is found, the client attempts to
the message to the indicated default mailbox: deliver the message to the indicated default mailbox:
C: A04 APPEND INBOX/Archive {309} C: A04 APPEND INBOX/Archive {309}
S: A04 NO [TRYCREATE] Mailbox does not exist: Archive/Personal S: A04 NO [TRYCREATE] Mailbox does not exist: INBOX/Archive
In this example, the default mailbox does not exist either. In that In this example, the default mailbox does not exist either. In that
case, the client MAY create the default mailbox and assign the case, the client MAY create the default mailbox and assign the
indicated special-use flag to it: indicated special-use attribute to it:
C: A05 CREATE INBOX/Archive (USE (\Archive)) C: A05 CREATE INBOX/Archive (USE (\Archive))
S: A05 OK Create completed S: A05 OK Create completed
Finally, the client completes the delivery: Finally, the client completes the delivery:
C: A06 APPEND INBOX/Archive {309} C: A06 APPEND INBOX/Archive {309}
S: + OK S: + OK
C: Date: Wed, 18 Jul 2018 22:00:09 +0200 C: Date: Wed, 18 Jul 2018 22:00:09 +0200
C: From: mooch@owatagu.siam.edu C: From: mooch@owatagu.siam.example
C: To: Fred Foobar <foobar@Blurdybloop.com> C: To: Fred Foobar <foobar@Blurdybloop.example>
C: Subject: afternoon meeting C: Subject: afternoon meeting
C: Message-Id: <Q234234-01012222@owatagu.siam.edu> C: Message-Id: <Q234234-01012222@owatagu.siam.example>
C: MIME-Version: 1.0 C: MIME-Version: 1.0
C: Content-Type: text/plain; charset=UTF-8 C: Content-Type: text/plain; charset=UTF-8
C: C:
C: Hi Fred, do you think we can meet again at 3:30 tomorrow? C: Hi Fred, do you think we can meet again at 3:30 tomorrow?
C: C:
S: A06 OK [APPENDUID 1533375901 2312] Append completed. S: A06 OK [APPENDUID 1533375901 2312] Append completed.
5. Sieve Capability Strings 5. Sieve Capability Strings
A Sieve implementation that defines the "specialuse_exists" test and A Sieve implementation that defines the "specialuse_exists" test and
skipping to change at page 9, line 26 skipping to change at page 9, line 26
specialuse_exists "${mailbox}" "\\Junk") { specialuse_exists "${mailbox}" "\\Junk") {
redirect "spam-report@example.org"; redirect "spam-report@example.org";
} }
7. Security Considerations 7. Security Considerations
Security considerations are discussed in [SIEVE], [VARIABLES], and Security considerations are discussed in [SIEVE], [VARIABLES], and
[SPECIAL-USE]. It is believed that this extension does not introduce [SPECIAL-USE]. It is believed that this extension does not introduce
any additional security concerns. any additional security concerns.
Note that this specification explicitly restricts the anonymous Note that this specification explicitly restricts the special-use
special-use mailbox to the user's personal namespace. First, this mailbox to the user's personal namespace. First, this avoids the
avoids the need to search the entire mail storage for mailboxes that need to search the entire mail storage for mailboxes that have a
have a particular special-use flag assigned. This could put undue particular special-use attribute assigned. This could put undue load
load on the system, while shared special-use mailboxes are deemed of on the system, while shared special-use mailboxes are deemed of
limited use with the currently defined special-use flags. Secondly, limited use with the currently defined special-use attributes.
it prevents security concerns with shared mailboxes that have Secondly, it prevents security concerns with shared mailboxes that
special-use flags assigned that apply to all users. Searching the have special-use attributes assigned that apply to all users.
entire mail storage for special-use mailboxes could lead to messages Searching the entire mail storage for special-use mailboxes could
unexpectedly or even maliciously being filed to shared mailboxes. lead to messages unexpectedly or even maliciously being filed to
shared mailboxes.
This restriction could be lifted for particular future special-use This restriction could be lifted for particular future special-use
flags, but such new flags should have a clear application for shared attributes, but such new attributes should have a clear application
mailboxes and the security concerns should be considered carefully. for shared mailboxes and the security concerns should be considered
carefully.
8. IANA Considerations 8. IANA Considerations
The following template specifies the IANA registration of the Sieve The following template specifies the IANA registration of the Sieve
extension specified in this document: extension specified in this document:
To: iana@iana.org To: iana@iana.org
Subject: Registration of new Sieve extension Subject: Registration of new Sieve extension
Capability name: special-use Capability name: special-use
Description: adds a test for checking whether an IMAP Description: adds a test for checking whether an IMAP
special-use attribute is assigned for a special-use attribute is assigned for a
particular mailbox or any mailbox, and it adds particular mailbox or any mailbox, and it adds
the ability to file messages into an anonymous the ability to file messages into a mailbox
mailbox that has a particular IMAP special-use identified solely by a special-use attribute.
attribute assigned.
RFC number: this RFC RFC number: this RFC
Contact address: Sieve mailing list <sieve@ietf.org> Contact address: Sieve mailing list <sieve@ietf.org>
This information should be added to the list of sieve extensions This information should be added to the list of sieve extensions
given on http://www.iana.org/assignments/sieve-extensions. given on http://www.iana.org/assignments/sieve-extensions.
9. Acknowledgements 9. Acknowledgements
Thanks to Stan Kalisch, Barry Leiba, Alexey Melnikov, Ken Murchison, Thanks to Stan Kalisch, Barry Leiba, Alexey Melnikov, Ken Murchison,
and Ned Freed for reviews and suggestions. and Ned Freed for reviews and suggestions.
skipping to change at page 10, line 42 skipping to change at page 10, line 41
[IMAP-METADATA] [IMAP-METADATA]
Daboo, C., "The IMAP METADATA Extension", RFC 5464, Daboo, C., "The IMAP METADATA Extension", RFC 5464,
DOI 10.17487/RFC5464, February 2009, DOI 10.17487/RFC5464, February 2009,
<http://www.rfc-editor.org/info/rfc5464>. <http://www.rfc-editor.org/info/rfc5464>.
[KEYWORDS] [KEYWORDS]
Bradner, S., "Key words for use in RFCs to Indicate Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[KEYWORDS-UPD]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[NAMESPACE] [NAMESPACE]
Gahrns, M. and C. Newman, "IMAP4 Namespace", RFC 2342, Gahrns, M. and C. Newman, "IMAP4 Namespace", RFC 2342,
DOI 10.17487/RFC2342, May 1998, <https://www.rfc- DOI 10.17487/RFC2342, May 1998, <https://www.rfc-
editor.org/info/rfc2342>. editor.org/info/rfc2342>.
[SIEVE] Guenther, P. and T. Showalter, "Sieve: An Email Filtering [SIEVE] Guenther, P. and T. Showalter, "Sieve: An Email Filtering
Language", RFC 5228, January 2008. Language", RFC 5228, January 2008.
[SIEVE-MAILBOX] [SIEVE-MAILBOX]
Melnikov, A., "The Sieve Mail-Filtering Language -- Melnikov, A., "The Sieve Mail-Filtering Language --
skipping to change at page 11, line 44 skipping to change at page 11, line 44
[LIST-EXTENDED] [LIST-EXTENDED]
Leiba, B. and A. Melnikov, "Internet Message Access Leiba, B. and A. Melnikov, "Internet Message Access
Protocol version 4 - LIST Command Extensions", RFC 5258, Protocol version 4 - LIST Command Extensions", RFC 5258,
DOI 10.17487/RFC5258, June 2008, <https://www.rfc- DOI 10.17487/RFC5258, June 2008, <https://www.rfc-
editor.org/info/rfc5258>. editor.org/info/rfc5258>.
Author's Address Author's Address
Stephan Bosch Stephan Bosch
Dovecot Oy Open Xchange Oy
Lars Sonckin Kaari 12 Lars Sonckin kaari 12
Espoo 02600 Espoo 02600
Finland Finland
Email: stephan.bosch@dovecot.fi Email: stephan.bosch@open-xchange.com
 End of changes. 37 change blocks. 
95 lines changed or deleted 111 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/