Snoozing Email with IMAP, JMAP, and Sieve
draft-ietf-extra-email-snooze-00

EXTRA                                                       K. Murchison
Internet-Draft                                                 R. Signes
Intended status: Standards Track                              N. Jenkins
Expires: 25 April 2024                                          Fastmail
                                                         23 October 2023

               Snoozing Email with IMAP, JMAP, and Sieve
                    draft-ietf-extra-email-snooze-00

Abstract

   This document describes the "snooze" extensions to IMAP, JMAP for
   Mail, and the Sieve Email Filtering Language.  The "snooze"
   extensions give these protocols the ability to postpone the
   appearance of an email message in a target mailbox until a later
   point in time.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 25 April 2024.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions Used in This Document . . . . . . . . . . . .   3
   2.  Mechanics of Snoozing and Awakening a Message . . . . . . . .   3
   3.  IMAP SNOOZE Extension . . . . . . . . . . . . . . . . . . . .   4
     3.1.  The \Snoozed Mailbox Attribute  . . . . . . . . . . . . .   4
     3.2.  SNOOZE Command  . . . . . . . . . . . . . . . . . . . . .   4
     3.3.  UID SNOOZE Command  . . . . . . . . . . . . . . . . . . .   5
     3.4.  Semantics of SNOOZE and UID SNOOZE  . . . . . . . . . . .   5
     3.5.  Interaction with Other Extensions . . . . . . . . . . . .   5
       3.5.1.  ANNOTATE  . . . . . . . . . . . . . . . . . . . . . .   6
     3.6.  Formal Syntax . . . . . . . . . . . . . . . . . . . . . .   6
   4.  JMAP Mail Snooze Extension  . . . . . . . . . . . . . . . . .   6
     4.1.  The "snoozed" Mailbox Role  . . . . . . . . . . . . . . .   6
     4.2.  Extension to the Email Object . . . . . . . . . . . . . .   7
   5.  Sieve Snooze Extension  . . . . . . . . . . . . . . . . . . .   8
     5.1.  Snooze Action . . . . . . . . . . . . . . . . . . . . . .   8
       5.1.1.  Mailbox Argument  . . . . . . . . . . . . . . . . . .   9
       5.1.2.  Times, TZID, and Weekdays Arguments . . . . . . . . .   9
       5.1.3.  Interaction with Extensions to the Fileinto Action  .  12
   6.  Implementation Status . . . . . . . . . . . . . . . . . . . .  14
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   8.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  15
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Registration of JMAP Capability . . . . . . . . . . . . .  16
     9.2.  Registration of IMAP Capability . . . . . . . . . . . . .  16
     9.3.  Registration of Sieve Extension . . . . . . . . . . . . .  16
     9.4.  Registration of Sieve Action  . . . . . . . . . . . . . .  17
     9.5.  Registration of IMAP Mailbox Name Attribute . . . . . . .  17
     9.6.  Registration of IMAP Annotation Entry . . . . . . . . . .  18
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  18
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  18
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  18
     11.2.  Informative References . . . . . . . . . . . . . . . . .  20
   Appendix A.  Change History (To be removed by RFC Editor before
           publication)  . . . . . . . . . . . . . . . . . . . . . .  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  20

1.  Introduction

   Users are not always ready, willing, or able to read and respond to
   email messages at the time of their arrival.  Sometimes it is
   desirable to have messages appear in a mailbox at a more convenient
   time for the user to act upon them.

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   This document defines extensions to the Internet Message Access
   Protocol (IMAP) [RFC9051], The JSON Meta Application Protocol (JMAP)
   for Mail [RFC8621], and the Sieve Email Filtering Language [RFC5228]
   that enable postponing the appearance of a message in a target
   mailbox until a later point in time, also known as "snoozing" a
   message.

   The IMAP and JMAP extensions allow for snoozing messages that are
   already present in the mailstore.  The Sieve extension allows for
   snoozing a message at the time of final delivery.

   A "snoozed" message is one that the user wants put into a less
   obtrusive location for a fixed time.  When that time is reached, the
   messaged is "awakened" back into higher visibility.

1.1.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Mechanics of Snoozing and Awakening a Message

   The extensions defined in this specification use the following
   procedure for snoozing and awakening messages:

   1.  The message is delivered to, or moved into, a "snoozed" mailbox
       in the mailstore.

   2.  The message is assigned three meta-data items:

       *  An awaken time - the time at which to move the message out of
          the "snoozed" mailbox.

       *  An optional target mailbox into which the message will be
          moved at the awaken time.

       *  An optional set of flag/keyword updates to be made when the
          message is awakened.

   3.  Messages MUST be accessible while in the "snoozed" mailbox.

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   4.  At the awaken time, the message is moved from the "snoozed"
       mailbox into the target mailbox, and any updates are made to the
       message flags/keywords.  If the target mailbox is not specified,
       or is not a valid or available target for the user, then the
       message is moved into the user's main mailbox.

3.  IMAP SNOOZE Extension

   The SNOOZE extension is present in any IMAP implementation that
   returns "SNOOZE" as one of the supported capabilities to the
   CAPABILITY command.

3.1.  The \Snoozed Mailbox Attribute

   Users may create a mailbox with an attribute of \Snoozed
   (Section 9.5), having the sole purpose of holding snoozed emails.
   This mailbox is exposed over JMAP as having the "snoozed" role.

   Implementations are REQUIRED to enforce the following restrictions on
   the \Snoozed mailbox:

   *  Messages MUST NOT be added to the \Snoozed mailbox with the
      APPEND, COPY, or MOVE commands.  The server MUST reject commands
      that attempt to use the \Snoozed mailbox as a target with a tagged
      NO response having the CANNOT response code.

   *  When executing COPY or MOVE commands on the \Snoozed mailbox, the
      server MUST NOT copy "snoozed" meta-data to the new message.  The
      new message is effectively awakened.

3.2.  SNOOZE Command

   Arguments:    sequence-set

                 date/time string

                 OPTIONAL add flag list

                 OPTIONAL remove flag list

                 OPTIONAL mailbox name

   Responses:    no specific responses for this command

   Result:       OK - snooze completed

                 NO - snooze error: can't snooze those messages

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                 BAD - command unknown or arguments invalid

3.3.  UID SNOOZE Command

   This extends the first form of the UID command (see [RFC9051],
   Section 6.4.9) to add the SNOOZE command defined above as a valid
   argument.

3.4.  Semantics of SNOOZE and UID SNOOZE

   The SNOOZE command takes two mandatory arguments: a message set
   (sequence numbers for SNOOZE, UIDs for UID SNOOZE) and a date/time
   string (awaken time); and three optional arguments: a named target
   mailbox, a list of flags to be added to the awakened messages, and a
   list of flags to be removed from the awakened messages.  Each message
   included in the set is moved (as per [RFC9051], Section 6.4.9) from
   the selected mailbox to the mailbox having the \Snoozed attribute.
   Additionally, the awaken time, any target mailbox name, and any flag
   lists are stored as "snoozed" meta-data on the messages.  This
   process appears to the client as a single action and has the same
   effect for each message as this sequence (using syntax from
   [RFC5257], Section 4.5):

   1.  [UID] STORE ANNOTATION (/snoozed (value.shared ...))

   2.  [UID] MOVE

   At the awaken time, each message is moved from the \Snoozed mailbox
   into the target mailbox, and any updates are made to the message
   flags.  If no target mailbox was specified or it is inaccessible,
   then the message is moved into the user's INBOX.  and has the same
   effect for each message as this sequence:

   1.  [UID] STORE +FLAGS.SILENT

   2.  [UID] STORE -FLAGS.SILENT

   3.  [UID] MOVE

3.5.  Interaction with Other Extensions

   Because of the similarity of SNOOZE to MOVE, extensions that affect
   MOVE affect SNOOZE in the same way.  Response codes listed in
   [RFC9051], Section 7.1, as well as those defined by extensions, are
   sent as indicated for MOVE.

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3.5.1.  ANNOTATE

   Servers supporting ANNOTATE [RFC5257] MAY expose the "snoozed" meta-
   data on messages as a read-only shared /snoozed (Section 9.5) entry.
   The value of the /snoozed entry MUST be a JSON string in the form of
   a snoozeDetails object (Section 4.2).

3.6.  Formal Syntax

   The following syntax specification uses the Augmented Backus-Naur
   Form (ABNF) notation as specified in [RFC5234].  [RFC9051] defines
   the non-terminals "capability", "command-select", "sequence-set",
   "mailbox", "date-time", and "flag-list".

   Except as noted otherwise, all alphabetic characters are case
   insensitive.  The use of upper or lower case characters to define
   token strings is for editorial clarity only.  Implementations MUST
   accept these strings in a case-insensitive fashion.

   capability     =/ "SNOOZE"

   command-select =/ snooze

   snooze         = "SNOOZE" SP sequence-set SP date-time
                    [ SP "+FLAGS" SP flag-list ]
                    [ SP "-FLAGS" SP flag-list ]
                    [ SP mailbox ]

   uid            = "UID" SP
                    (copy / move / fetch / search / store /
                     uid-expunge / snooze)

4.  JMAP Mail Snooze Extension

   The capabilities object is returned as part of the JMAP Session
   object; see [RFC8620], Section 2.  Servers supporting this
   specification MUST add a property named
   "urn:ietf:params:jmap:mail:snooze" to the capabilities object.  The
   value of this property is an empty object in both the JMAP session
   "capabilities" property and an account's "accountCapabilities"
   property.

4.1.  The "snoozed" Mailbox Role

   Users may create a mailbox with a role of "snoozed", having the sole
   purpose of holding snoozed emails.  This mailbox is exposed over IMAP
   as having the \Snoozed (Section 9.5) attribute.

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4.2.  Extension to the Email Object

   The Email [RFC8621], Section 4.1 object gains a new property:

   *  *snoozed*: SnoozeDetails|null (immutable)

      If in the mailbox with role snoozed, this Email will be moved from
      there according to the details in this object.  Otherwise, this is
      a record of when it was snoozed in the past.

   A *SnoozeDetails* object has the following properties:

   *  *until*: UTCDate

      The time at which to move the message out of the "snoozed"
      mailbox.

   *  *moveToMailboxId*: String (optional)

      If set and a valid mailbox id for the user, this is where the
      Email will be moved at the awaken time.  Otherwise, the Email will
      be moved to the user's inbox.

   *  *setKeywords*: String[Boolean] (optional)

      If set, when the message is awakened it will also have keywords
      modified.  The keys of the object are the keyword names.  Names
      that map to true are keywords to be added.  Names that map to
      false are keywords to remove.

   The *snoozed* property has the following rules and restrictions:

   *  It is treated as an immutable property, i.e. it cannot be updated
      on an existing copy in a mailbox, it must cause a new copy (with a
      new UID).

   *  If an Email is in more than one mailbox (i.e. the same GUID is in
      multiple mailboxes), *snoozed* MUST only be set on one of the
      copies.

   *  When setting *snoozed* to a non-null value in an Email/set method:

      -  If the email is already in the Snoozed mailbox and not being
         removed from this mailbox, replace the copy in the Snoozed
         mailbox and set the SnoozeDetails on the new email.

      -  Otherwise, if adding the Email to a single new mailbox, set the
         SnoozeDetails on this copy.

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      -  Otherwise, if adding the Email to multiple mailboxes, set the
         SnoozeDetails on the copy in:

         o  The Snoozed mailbox if this is being added.

         o  Otherwise, the mailbox with the id in the moveToMailboxId
            property of the SnoozeDetails object (or inbox if this
            property is omitted), if this is being added.

         If neither apply, reject the create/update with an
         invalidProperties error.

      -  If not adding the Email to a new mailbox, replace the copy that
         currently has SnoozeDetails.  If none, reject the update with
         an invalidProperties error.

      -  Clear any existing SnoozeDetails from Emails in any other
         mailbox (this will involve replacing the copy with a new UID of
         course, as it's immutable).

   *  When removing the mailbox with which *snoozed* is associated from
      an Email, the snooze is implicitly cleared (i.e. it is not
      implicitly copied to another copy of the message; it must be
      explicitly set if the client wants to preserve it).

5.  Sieve Snooze Extension

   Sieve implementations that support this extension have an identifier
   of "snooze" for use with the capability mechanism.

   Conventions for notations are as in Section 1.1 of [RFC5228],
   including use of the "Usage:" label for the definition of action and
   tagged arguments syntax.

5.1.  Snooze Action

   Usage: snooze *AWAKEN-OPTIONS <times: string-list>

   The AWAKEN-OPTIONS argument is defined here in ABNF [RFC5234] syntax
   so that it can be modified by other extensions.

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   AWAKEN-OPTIONS = MAILBOX / WEEKDAYS / TZID
                     ; each option MUST NOT appear more than once
                     ; however, per Section 2.6.2 of RFC 5228,
                     ; the tagged arguments in AWAKEN-OPTIONS
                     ; may appear in any order

   MAILBOX  = ":mailbox" string
   WEEKDAYS = ":weekdays" string-list
   TZID     = ":tzid" string

   The "snooze" action cancels the implicit keep and postpones delivery
   of the message into the specified mailbox at a later point in time.

   The snooze action is semantically equivalent to a delayed fileinto
   action (see Section 4.1 of [RFC5228]).  The arguments of the snooze
   action specify when, where, and how the awakened message will be
   filed.

   Implementations MUST snooze and awaken messages per Section 2.
   Specifically, a Sieve interpreter whose mailstore is accessible via
   IMAP and/or JMAP MUST utilize a "snoozed" mailbox per Sections
   Section 3 and Section 4 respectively.

5.1.1.  Mailbox Argument

   The optional :mailbox argument is used to specify the target mailbox
   that the message will be filed into when it is awakened.  It is
   equivalent to the mailbox argument of the fileinto action (see
   Section 4.1 of [RFC5228]).

   If :mailbox is omitted, or if the specified mailbox doesn't exist at
   the time of awakening, the message will be filed into the user's main
   mailbox.  For instance, in an implementation where an IMAP server is
   running scripts on behalf of the user at time of delivery, the user's
   "INBOX" would be the implicit target for awakening messages.

5.1.2.  Times, TZID, and Weekdays Arguments

   The required times argument, along with the optional :tzid and
   :weekdays arguments, are used to specify when a snoozed message will
   be awakened.  Each time is specified in "hh:mm:ss" format and is
   interpreted as the local time in the time zone specified by the :tzid
   argument.

   The value of the :tzid argument MUST be a time zone identifier from
   the IANA Time Zone Database [tzdb].  If :tzid is omitted, the time
   zone of the Sieve interpreter is used.

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   The :weekdays argument specifies the set of days on which the
   specified set of times apply.  Each day of the week is expressed as
   an integer between "0" and "6". "0" is Sunday, "1" is Monday, etc.
   This syntax matches that of the "weekday" date-part argument to the
   date test extension (see Section 4.2 of [RFC5260]).  If :weekdays is
   omitted, the set of times applies to every day of the week.

   The combination of the weekdays and times form a chronological list
   of awaken times.  When a message is snoozed, it is assigned the next
   future awaken time in the list.  If a message is snoozed on a day
   with no awaken times, or after the last awaken time on a given day,
   the first awaken time on the next available day is used.

   If the local time in the specified time zone occurs more than once
   (daylight saving to standard time transition), the first occurrence
   of the specified time value is used.  If the local time in the
   specified time zone does not occur (standard to daylight saving time
   transition), the specified time value is interpreted using the UTC
   offset prior to the transition.

5.1.2.1.  Awaken Times Examples

   The following examples show, given the specified snooze action and a
   set of message arrival times, the corresponding times at which the
   message would be awakened and filed.

   The following example shows awaken times rolling into the next day or
   week.  Note that 2020-07-30 falls on a Thursday.

   require "snooze";
   snooze :weekdays ["1", "3", "5", "2", "4"]
          :tzid "Australia/Melbourne" ["12:00:00",
                                       "08:00:00", "16:00:00"];

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   +======================+=====================+=====================+
   |    Arrival (UTC)     | Arrival (Melbourne) |  Awaken (Melbourne) |
   +======================+=====================+=====================+
   | 2020-07-30T00:00:00Z | --07-30T10:00:00+10 | --07-30T12:00:00+10 |
   +----------------------+---------------------+---------------------+
   | 2020-07-30T04:00:00Z | --07-30T14:00:00+10 | --07-30T16:00:00+10 |
   +----------------------+---------------------+---------------------+
   | 2020-07-30T08:00:00Z | --07-30T18:00:00+10 | --07-31T08:00:00+10 |
   +----------------------+---------------------+---------------------+
   | 2020-07-31T12:00:00Z | --07-31T22:00:00+10 | --08-03T08:00:00+10 |
   +----------------------+---------------------+---------------------+
   | 2020-08-01T16:00:00Z | --08-02T02:00:00+10 | --08-03T08:00:00+10 |
   +----------------------+---------------------+---------------------+

                                 Table 1

   The following example shows awaken times falling before, during, and
   after a daylight saving to standard time transition.  Note that the
   transition occurs at 2020-11-01T02:00:00-04.

   require "snooze";
   snooze :tzid "America/New_York" "01:30:00";

   +======================+=====================+=====================+
   |    Arrival (UTC)     |  Arrival (New York) |  Awaken (New York)  |
   +======================+=====================+=====================+
   | 2020-11-01T05:00:00Z | --11-01T01:00:00-04 | --11-01T01:30:00-04 |
   +----------------------+---------------------+---------------------+
   | 2020-11-01T06:00:00Z | --11-01T01:00:00-05 | --11-02T01:30:00-05 |
   +----------------------+---------------------+---------------------+
   | 2020-11-01T07:00:00Z | --11-01T02:00:00-05 | --11-02T01:30:00-05 |
   +----------------------+---------------------+---------------------+

                                 Table 2

   The following example shows awaken times falling before, during, and
   after a standard to daylight saving time transition.  Note that the
   transition occurs at 2021-03-14T02:00:00-05.

   require "snooze";
   snooze :tzid "America/New_York" "02:30:00";

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   +======================+=====================+=====================+
   |    Arrival (UTC)     |  Arrival (New York) |  Awaken (New York)  |
   +======================+=====================+=====================+
   | 2021-03-13T06:30:00Z | --03-13T01:30:00-05 | --03-13T02:30:00-05 |
   +----------------------+---------------------+---------------------+
   | 2021-03-14T06:30:00Z | --03-14T01:30:00-05 | --03-14T03:30:00-04 |
   +----------------------+---------------------+---------------------+
   | 2021-03-14T07:30:00Z | --03-14T03:30:00-04 | --03-15T02:30:00-04 |
   +----------------------+---------------------+---------------------+

                                 Table 3

5.1.3.  Interaction with Extensions to the Fileinto Action

   Some tagged arguments defined in extensions to the fileinto action
   can be used together with the snooze action.  The sections below
   describe these interactions.  Tagged arguments in future extensions
   to the fileinto action need to describe their interaction with the
   snooze extension, if any.

   When any fileinto extension arguments are used with the snooze
   extension, the corresponding extension MUST be enabled, and the
   arguments are defined to have the same syntax, semantics, and
   treatment as they do with the fileinto action.

5.1.3.1.  Imap4flags Extension

   When the "imap4flags" [RFC5232] extension is enabled in a script, two
   additional tagged arguments are added to "snooze" that allow
   manipulating the set of flags on a snoozed message.

   AWAKEN-OPTIONS /= ADDFLAGS / REMOVEFLAGS

   ADDFLAGS    = ":addflags" string-list
   REMOVEFLAGS = ":removeflags" string-list

   The optional :addflags and :removeflags arguments are used to specify
   which IMAP [RFC9051] flags should be added to and/or removed from the
   set of IMAP flags present on the snoozed message at the time of
   awakening.  Note the set of IMAP flags present at the time of
   awakening may be the empty set.

   If the "setflag" and/or "addflag" actions have been used to store
   IMAP flags in the imap4flags internal variable, the Sieve interpreter
   MUST use the current value of the internal variable as the set of
   flags to associate with the message when storing it into the
   "snoozed" mailbox.

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   This document doesn't dictate how the Sieve interpreter will set the
   IMAP flags.  In particular, the Sieve interpreter may work as an IMAP
   client or may have direct access to the mailstore.

   The general requirements for flag handling specified in Section 2 of
   [RFC5232] MUST be followed.

5.1.3.1.1.  Example

   The following example leverages the Date [RFC5260], Relational
   [RFC5231], and Imap4flags [RFC5232] extensions to snooze messages
   received after business hours until the following work day.  Note
   that the message is marked as important when it is snoozed, and will
   be marked as unread when it is awakened.

   require ["snooze", "imap4flags", "date", "relational"];

   if anyof(header :is "from" "boss@example.com",
            currentdate :is "weekday" "0",
            currentdate :is "weekday" "6",
            currentdate :value "ge" "hour" "17") {
       setflag "\\Important";
       snooze :removeflags "\\Seen"
              :weekdays ["1". "2", "3", "4", "5"]
              :tzid "American/New_York", "09:00";
   }

5.1.3.2.  Mailbox Extension

   This document extends the definition of the ":create" [RFC5490]
   tagged argument so that it can be used with the snooze action.

   AWAKEN-OPTIONS /= CREATE

   CREATE = ":create"
              ; MUST NOT be appear unless MAILBOX also appears

   If the optional ":create" argument is specified with snooze, it
   instructs the Sieve interpreter to create the target mailbox, if
   needed, before attempting to file the awakened message into the
   target mailbox.

5.1.3.3.  Special-Use Extension

   This document extends the definition of the ":specialuse" [RFC8579]
   tagged argument so that it can be used with the snooze action.

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   AWAKEN-OPTIONS /= SPECIAL-USE

   SPECIAL-USE = ":specialuse" string

   If the optional ":specialuse" argument is specified with snooze, it
   instructs the Sieve interpreter to check whether a mailbox exists
   with the specific special-use flag assigned to it.  If such a mailbox
   exists, the awakened message is filed into the special-use mailbox.
   Otherwise, the awakened message is filed into the target mailbox.

   If both the optional ":specialuse" and ":create" arguments are
   specified with snooze, the Sieve interpreter is instructed to create
   the target mailbox per Section 4.1 of [RFC8579], if needed.

5.1.3.4.  MailboxID Extension

   This document extends the definition of the ":mailboxid" [RFC9042]
   tagged argument so that it can be used with the snooze action.

   AWAKEN-OPTIONS /= MAILBOXID

   MAILBOXID = ":mailboxid" string

   If the optional ":mailboxid" argument is specified with snooze, it
   instructs the Sieve interpreter to check whether a mailbox exists in
   the user's personal namespace [RFC2342] with the specified MAILBOXID
   [RFC8474].  If such a mailbox exists, the awakened message is filed
   into that mailbox.  Otherwise, the awakened message is filed into the
   target mailbox.

   It is an error to specify both ":mailboxid" and ":specialuse" in the
   same snooze action.

6.  Implementation Status

   < RFC Editor: before publication please remove this section and the
   reference to [RFC7942] >

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   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in [RFC7942].
   The description of implementations in this section is intended to
   assist the IETF in its decision processes in progressing drafts to
   RFCs.  Please note that the listing of any individual implementation
   here does not imply endorsement by the IETF.  Furthermore, no effort
   has been spent to verify the information presented here that was
   supplied by IETF contributors.  This is not intended as, and must not
   be construed to be, a catalog of available implementations or their
   features.  Readers are advised to note that other implementations may
   exist.

   According to [RFC7942], "this will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature.
   It is up to the individual working groups to use this information as
   they see fit".

6.1.  Cyrus Server

   The open source Cyrus Server (http://www.cyrusimap.org/) project is a
   highly scalable enterprise mail system which supports IMAP, JMAP, and
   Sieve email filtering at the point of final delivery.  This
   production level implementation supports the JMAP and Sieve variants
   of "snooze" described in this document.  This implementation is
   freely distributable under a BSD style license from Computing
   Services at Carnegie Mellon University (http://www.cmu.edu/
   computing/).

7.  Security Considerations

   Security considerations are discussed in [RFC5228], [RFC5232],
   [RFC8579], and [RFC9042].

   It is believed that this extension doesn't introduce any additional
   security concerns.

8.  Privacy Considerations

   It is believed that this extension doesn't introduce any privacy
   considerations beyond those in [RFC5228].

9.  IANA Considerations

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9.1.  Registration of JMAP Capability

   This document defines the following new JMAP capability to be added
   to the registry defined in Section 9.4 of [RFC8620] and located here:
   https://www.iana.org/assignments/jmap/jmap.xhtml#jmap-capabilities

   IANA are requested to add a capability to the JMAP Capabilities
   registry:

      Capability Name: urn:ietf:params:jmap:mail:snooze

      Specification document: RFC XXXX

      Intended use: common

      Change Controller: IETF

      Security and privacy considerations: RFC XXXX, Section 7

9.2.  Registration of IMAP Capability

   IANA are requested to add "SNOOZE" to the IMAP Capabilities registry,
   https://www.iana.org/assignments/imap4-capabilities

9.3.  Registration of Sieve Extension

   This document defines the following new Sieve extension to be added
   to the registry defined in Section 6.2 of [RFC5228] and located here:
   https://www.iana.org/assignments/sieve-extensions/sieve-
   extensions.xhtml#sieve-extensions

   IANA are requested to add a capability to the Sieve Extensions
   registry:

      To: iana@iana.org

      Subject: Registration of new Sieve extension

      Capability name: snooze

      Description: Adds the "snooze" action command to postpone delivery
      of a message into a target mailbox until a later point in time.

      RFC number: RFC XXXX

      Contact address: The Sieve discussion list <sieve@ietf.org>

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9.4.  Registration of Sieve Action

   This document defines the following new Sieve action to be added to
   the registry defined in Section 2.1 of [RFC9122].

   IANA are requested to add an action to the Sieve Action registry:

      Name: snooze

      Description: Postpone delivery of a message into a target mailbox
      until a later point in time.

      References: RFC XXXX, [RFC5232], [RFC5490], [RFC8579], [RFC9042]

      Capabilities: "snooze", "imap4flags", "mailbox", "special-use",
      "mailboxid".

      Interactions: Is not compatible with the reject or ereject
      actions.

      Cancels Implicit Keep?: Y

      Use with IMAP Events?: Y

      Comments: Requires a special "snoozed" mailbox in the mailstore.

9.5.  Registration of IMAP Mailbox Name Attribute

   This document defines the following new IMAP mailbox name attribute
   to be added to the registry defined in Section 6.2 of [RFC8457] and
   located here: https://www.iana.org/assignments/imap-mailbox-name-
   attributes/imap-mailbox-name-attributes.xhtml#imap-mailbox-name-
   attributes

   IANA are requested to add an attribute to the IMAP Mailbox Name
   Attribute registry:

      To: iana@iana.org

      Subject: Registration of new IMAP Mailbox Name Attribute

      Attribute name: Snoozed

      Description: Messages that have been snoozed.

      Reference: RFC XXXX

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9.6.  Registration of IMAP Annotation Entry

   This document defines the following new IMAP annotation entry to be
   added to the registry defined in Section 6 of [RFC5257] and located
   here: https://www.iana.org/assignments/imap-annotate-extension/imap-
   annotate-extension.xhtml#imap-annotate-extension-entries

      To: iana@iana.org

      Subject: IMAP Annotate Registration

      Please register the following Annotate item:

      [X]Entry         [] Attribute

      Name: /snoozed

      Description: RFC XXXX, Section 3.5.1.

      Content-Type: application/json

      Contact person: Ken Murchison

               email: murch@fastmailteam.com

10.  Acknowledgments

   The authors would like to thank the following individuals for
   contributing their ideas and support for writing this specification:
   Ned Freed, Barry Leiba, Alexey Melnikov, and Pete Resnick.

11.  References

11.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2342]  Gahrns, M. and C. Newman, "IMAP4 Namespace", RFC 2342,
              DOI 10.17487/RFC2342, May 1998,
              <https://www.rfc-editor.org/info/rfc2342>.

   [RFC5228]  Guenther, P., Ed. and T. Showalter, Ed., "Sieve: An Email
              Filtering Language", RFC 5228, DOI 10.17487/RFC5228,
              January 2008, <https://www.rfc-editor.org/info/rfc5228>.

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   [RFC5232]  Melnikov, A., "Sieve Email Filtering: Imap4flags
              Extension", RFC 5232, DOI 10.17487/RFC5232, January 2008,
              <https://www.rfc-editor.org/info/rfc5232>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <https://www.rfc-editor.org/info/rfc5234>.

   [RFC5490]  Melnikov, A., "The Sieve Mail-Filtering Language --
              Extensions for Checking Mailbox Status and Accessing
              Mailbox Metadata", RFC 5490, DOI 10.17487/RFC5490, March
              2009, <https://www.rfc-editor.org/info/rfc5490>.

   [RFC8174]  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>.

   [RFC8457]  Leiba, B., Ed., "IMAP "$Important" Keyword and
              "\Important" Special-Use Attribute", RFC 8457,
              DOI 10.17487/RFC8457, September 2018,
              <https://www.rfc-editor.org/info/rfc8457>.

   [RFC8474]  Gondwana, B., Ed., "IMAP Extension for Object
              Identifiers", RFC 8474, DOI 10.17487/RFC8474, September
              2018, <https://www.rfc-editor.org/info/rfc8474>.

   [RFC8579]  Bosch, S., "Sieve Email Filtering: Delivering to Special-
              Use Mailboxes", RFC 8579, DOI 10.17487/RFC8579, May 2019,
              <https://www.rfc-editor.org/info/rfc8579>.

   [RFC8620]  Jenkins, N. and C. Newman, "The JSON Meta Application
              Protocol (JMAP)", RFC 8620, DOI 10.17487/RFC8620, July
              2019, <https://www.rfc-editor.org/info/rfc8620>.

   [RFC8621]  Jenkins, N. and C. Newman, "The JSON Meta Application
              Protocol (JMAP) for Mail", RFC 8621, DOI 10.17487/RFC8621,
              August 2019, <https://www.rfc-editor.org/info/rfc8621>.

   [RFC9042]  Gondwana, B., Ed., "Sieve Email Filtering: Delivery by
              MAILBOXID", RFC 9042, DOI 10.17487/RFC9042, June 2021,
              <https://www.rfc-editor.org/info/rfc9042>.

   [RFC9051]  Melnikov, A., Ed. and B. Leiba, Ed., "Internet Message
              Access Protocol (IMAP) - Version 4rev2", RFC 9051,
              DOI 10.17487/RFC9051, August 2021,
              <https://www.rfc-editor.org/info/rfc9051>.

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   [RFC9122]  Melnikov, A. and K. Murchison, "IANA Registry for Sieve
              Actions", RFC 9122, DOI 10.17487/RFC9122, June 2023,
              <https://www.rfc-editor.org/info/rfc9122>.

   [tzdb]     Internet Assigned Numbers Authority, "Time Zone Database",
              <https://www.iana.org/time-zones>.

11.2.  Informative References

   [RFC5231]  Segmuller, W. and B. Leiba, "Sieve Email Filtering:
              Relational Extension", RFC 5231, DOI 10.17487/RFC5231,
              January 2008, <https://www.rfc-editor.org/info/rfc5231>.

   [RFC5257]  Daboo, C. and R. Gellens, "Internet Message Access
              Protocol - ANNOTATE Extension", RFC 5257,
              DOI 10.17487/RFC5257, June 2008,
              <https://www.rfc-editor.org/info/rfc5257>.

   [RFC5260]  Freed, N., "Sieve Email Filtering: Date and Index
              Extensions", RFC 5260, DOI 10.17487/RFC5260, July 2008,
              <https://www.rfc-editor.org/info/rfc5260>.

   [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", BCP 205,
              RFC 7942, DOI 10.17487/RFC7942, July 2016,
              <https://www.rfc-editor.org/info/rfc7942>.

Appendix A.  Change History (To be removed by RFC Editor before
             publication)

   Changes since draft-ietf-extra-sieve-snooze-00:

   *  Added snooze functionality to IMAP and JMAP.

   *  Miscellaneous editorial changes.

Authors' Addresses

   Kenneth Murchison
   Fastmail US LLC
   1429 Walnut Street - Suite 1201
   Philadelphia, PA 19102
   United States of America
   Email: murch@fastmailteam.com

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   Ricardo Signes
   Fastmail US LLC
   1429 Walnut Street - Suite 1201
   Philadelphia, PA 19102
   United States of America
   Email: rjbs@fastmailteam.com

   Neil Jenkins
   Fastmail Pty Ltd
   Level 2, 114 William Street
   Melbourne VIC 3000
   Australia
   Email: neilj@fastmailteam.com

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