draft-ietf-extra-imap-savedate-01.txt   rfc8514.txt 
EXTRA S. Bosch Internet Engineering Task Force (IETF) S. Bosch
Internet-Draft Dovecot Oy Request for Comments: 8514 Open Xchange Oy
Intended status: Standards Track May 4, 2018 Category: Standards Track January 2019
Expires: November 5, 2018 ISSN: 2070-1721
Internet Message Access Protocol (IMAP) - SAVEDATE Extension Internet Message Access Protocol (IMAP) - SAVEDATE Extension
draft-ietf-extra-imap-savedate-01
Abstract Abstract
This document adds a new capability called "SAVEDATE" to the Internet This document adds a new capability called "SAVEDATE" to the Internet
Message Access Protocol (IMAP). It defines a new IMAP message Message Access Protocol (IMAP). It defines a new IMAP message
attribute called 'save date' that, unlike the existing 'internal attribute called "save date" that, unlike the existing "internal
date' attribute, always indicates the moment at which the message was date" attribute, always indicates the moment at which the message was
saved in its current mailbox. The SAVEDATE capability extends the saved in its current mailbox. The SAVEDATE capability extends the
FETCH command with the means to retrieve the save date attribute and FETCH command with the means to retrieve the save date attribute and
it extends the SEARCH command to allow using that attribute in extends the SEARCH command to allow using the save date attribute in
searching criteria. searching criteria.
Status of This Memo Status of This Memo
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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.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Save Date Message Attribute . . . . . . . . . . . . . . . . . 3 3. Save Date Message Attribute . . . . . . . . . . . . . . . . . 3
4. IMAP Protocol Changes . . . . . . . . . . . . . . . . . . . . 4 4. IMAP Protocol Changes . . . . . . . . . . . . . . . . . . . . 4
4.1. CAPABILITY Identification . . . . . . . . . . . . . . . . 4 4.1. CAPABILITY Identification . . . . . . . . . . . . . . . . 4
4.2. FETCH Command and Response Extensions . . . . . . . . . . 4 4.2. FETCH Command and Response Extensions . . . . . . . . . . 4
4.3. SEARCH Command Extension . . . . . . . . . . . . . . . . 4 4.3. SEARCH Command Extension . . . . . . . . . . . . . . . . 4
5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 8. Normative References . . . . . . . . . . . . . . . . . . . . 6
9. Normative References . . . . . . . . . . . . . . . . . . . . 6 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
This document extends Internet Message Access Protocol (IMAP) This document extends the Internet Message Access Protocol (IMAP)
[IMAP4rev1] with a new capability called "SAVEDATE". This capability [IMAP4rev1] with a new capability called "SAVEDATE". This capability
adds a new IMAP message attribute called 'save date'. The save date adds a new IMAP message attribute called "save date". The save date
is the date and time at which a message was saved in the mailbox it is the date and time at which a message was saved in the mailbox in
currently resides. The save date is similar to the existing internal which it currently resides. The save date is similar to the existing
date attribute in that it is set at the time of delivery. However, "internal date" attribute in that it is set at the time of delivery.
the internal date attribute can be set to an arbitrary value for However, the internal date attribute can be set to an arbitrary value
messages delivered to the mailbox using the APPEND command and it is for messages delivered to the mailbox using the APPEND command and is
usually copied from the source message for messages delivered using usually copied from the source message for messages delivered using
the COPY command. In contrast, the save date attribute is always set the COPY command. In contrast, the save date attribute is always set
to the current date and time at the moment the message is saved in to the current date and time at the moment the message is saved in
the mailbox, irrespective of how the message is delivered and from the mailbox, irrespective of how the message is delivered and from
where it originates. where it originates.
The save date message attribute is useful for implementing automated The save date attribute is useful for implementing automated removal
removal of messages from a mailbox after a configured amount of time. of messages from a mailbox after a configured amount of time. For
For that application, it is necessary to know when the message was that application, it is necessary to know when the message was saved
saved in the mailbox, which cannot be reliably determined using the in the mailbox, which cannot be reliably determined using the
the internal date attribute. internal date attribute.
For example, a common client usage pattern is to move deleted For example, a common client usage pattern is to move deleted
messages to a Trash mailbox; these messages are considered "deleted" messages to a Trash mailbox. These messages are considered "deleted"
at the time they are moved to the Trash mailbox. In an effort to at the time they are moved to the Trash mailbox. In an effort to
limit the size of the Trash mailbox, a client may subsequently desire limit the size of the Trash mailbox, a client may subsequently desire
to permanently remove (expunge) all messages in that Trash mailbox to permanently remove (expunge) all messages in that Trash mailbox
deleted before a certain time (e.g. a configurable expiration deleted before a certain time (e.g., a configurable expiration
interval). In that case, the internal date attribute cannot be used, interval). In that case, the internal date attribute cannot be used
since it likely refers to the time at which the message was since it likely refers to the time at which the message was
originally received. The proper time comparison attribute should originally received. The proper time comparison attribute should
instead be the time at which the message was saved to the Trash instead be the time at which the message was saved to the Trash
mailbox. Similar usage patterns can be observed for Archiving mailbox. Similar usage patterns can be observed for archiving
solutions. solutions.
The SAVEDATE capability extends the FETCH command and response to The SAVEDATE capability extends the FETCH command and response to
allow retrieving the date and time at which a message was saved. allow retrieving the date and time at which a message was saved.
Also, the SAVEDATE capability extends the SEARCH command to allow Also, the SAVEDATE capability extends the SEARCH command to allow
searching messages with criteria based on when it was saved in the searching messages with criteria based on when they were saved in the
mailbox. mailbox.
2. Conventions Used in This Document 2. Conventions Used in This Document
In examples, "C:" indicates lines sent by a client that is connected In examples, "C:" indicates lines sent by a client that is connected
to a server. "S:" indicates lines sent by the server to the client. to a server. "S:" indicates lines sent by the server to the client.
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.
3. Save Date Message Attribute 3. Save Date Message Attribute
The save date message attribute is the date and time at which the The save date message attribute is the date and time at which the
message was saved in the mailbox it is now located in. Unlike the message was saved in the mailbox it is now located in. Unlike the
internal date attribute defined by [IMAP4rev1], this date and time internal date message attribute defined by [IMAP4rev1], this date and
value cannot be set arbitrarily when a message is delivered by the time value cannot be set arbitrarily when a message is delivered by
IMAP APPEND command. Also, when a message is delivered to the the IMAP APPEND command. Also, when a message is delivered to the
mailbox by the IMAP COPY command [IMAP4rev1] or the IMAP MOVE command mailbox by the IMAP COPY command [IMAP4rev1] or the IMAP MOVE command
[IMAP-MOVE], the save date attribute is not copied from the source [IMAP-MOVE], the save date attribute is not copied from the source
message. Instead, the current date and time at which the message is message. Instead, the current date and time at which the message is
delivered to a mailbox MUST be used to set the save date attribute. delivered to a mailbox MUST be used to set the save date attribute.
Once calculated, the save date attribute MUST NOT change as long as Once calculated, the save date attribute MUST NOT change as long as
the message is contained within the same mailbox. the message is contained within the same mailbox.
This means that when the message is copied to another mailbox, the This means that when the message is copied to another mailbox, the
save date of the message in source mailbox remains unaffected; only save date of the message in the source mailbox remains unaffected;
the new copy of the message gets a new save date. Consequently, when only the new copy of the message gets a new save date. Consequently,
the the message is moved to another mailbox, either using the MOVE when the message is moved to another mailbox, either using the MOVE
command or a command sequence involving the COPY command [IMAP-MOVE], command or a command sequence involving the COPY command [IMAP-MOVE],
the message always gets a new save date in the destination mailbox. the message always gets a new save date in the destination mailbox.
For some specific mailboxes, the underlying storage may not support For some specific mailboxes, the underlying storage may not support
the save date message attribute. The handling of this situation is the save date attribute. The handling of this situation is described
described in detail in the next section for each involved IMAP in detail in the next section for each involved IMAP command.
command.
4. IMAP Protocol Changes 4. IMAP Protocol Changes
4.1. CAPABILITY Identification 4.1. CAPABILITY Identification
IMAP servers that support this extension MUST include "SAVEDATE" in IMAP servers that support this extension MUST include "SAVEDATE" in
the response list to the CAPABILITY command. the response list to the CAPABILITY command.
4.2. FETCH Command and Response Extensions 4.2. FETCH Command and Response Extensions
skipping to change at page 5, line 48 skipping to change at page 6, line 7
"SAVEDSINCE" SP date / "SAVEDSINCE" SP date /
"SAVEDATESUPPORTED" "SAVEDATESUPPORTED"
6. Security Considerations 6. Security Considerations
There are no known additional security issues with this extension There are no known additional security issues with this extension
beyond those described in the base protocol described in [IMAP4rev1]. beyond those described in the base protocol described in [IMAP4rev1].
7. IANA Considerations 7. IANA Considerations
The IANA is requested to add "SAVEDATE" to the "IMAP Capabilities" IANA has added "SAVEDATE" to the "IMAP Capabilities" registry located
registry located at <http://www.iana.org/assignments/imap- at <https://www.iana.org/assignments/imap-capabilities>.
capabilities>.
8. Acknowledgements
Thanks to Bron Gondwana, Alexey Melnikov, Timo Sirainen, and Michael
Slusarz for reviews and suggestions.
9. Normative References 8. Normative References
[ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax [ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/rfc/rfc5234>.
[IMAP-MOVE] [IMAP-MOVE]
Gulbrandsen, A. and N. Freed, "Internet Message Access Gulbrandsen, A. and N. Freed, "Internet Message Access
Protocol (IMAP) - MOVE Extension", RFC 6851, January 2013. Protocol (IMAP) - MOVE Extension", RFC 6851,
DOI 10.17487/RFC6851, January 2013,
<https://www.rfc-editor.org/rfc/rfc6851>.
[IMAP4rev1] [IMAP4rev1]
Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, March 2003. 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003,
<https://www.rfc-editor.org/rfc/rfc3501>.
[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,
Requirement Levels", BCP 14, RFC 2119, March 1997. DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[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>.
[MULTISEARCH] [MULTISEARCH]
Leiba, B. and A. Melnikov, "IMAP4 Multimailbox SEARCH Leiba, B. and A. Melnikov, "IMAP4 Multimailbox SEARCH
Extension", RFC 7377, DOI 10.17487/RFC7377, October 2014, Extension", RFC 7377, DOI 10.17487/RFC7377, October 2014,
<https://www.rfc-editor.org/info/rfc7377>. <https://www.rfc-editor.org/info/rfc7377>.
Acknowledgements
Thanks to Bron Gondwana, Alexey Melnikov, Timo Sirainen, and Michael
Slusarz for reviews and suggestions.
Author's Address Author's Address
Stephan Bosch Stephan Bosch
Dovecot Oy Open Xchange Oy
Lars Sonckin Kaari 10 Lars Sonckin kaari 12
Espoo 02600 Espoo 02600
Finland Finland
Email: stephan.bosch@dovecot.fi Email: stephan.bosch@open-xchange.com
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