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.
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