draft-murchison-sieve-snooze.xml

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<rfc category="std" ipr='trust200902'
     docName='draft-murchison-sieve-snooze-00'>
  <front>
    <title abbrev="Sieve Snooze">Sieve Email Filtering: Snooze Extension</title>
    <author initials="K." surname="Murchison" fullname="Kenneth Murchison">
      <organization abbrev="Fastmail">Fastmail US LLC</organization>
      <address>
        <postal>
          <street>1429 Walnut Street - Suite 1201</street>
          <city>Philadelphia</city> <region>PA</region>
          <code>19102</code> <country>USA</country>
        </postal>
        <email>murch@fastmailteam.com</email>
      </address>
    </author>

    <author initials="R." surname="Signes" fullname="Ricardo Signes">
      <organization abbrev="Fastmail">Fastmail US LLC</organization>
      <address>
        <postal>
          <street>1429 Walnut Street - Suite 1201</street>
          <city>Philadelphia</city> <region>PA</region>
          <code>19102</code> <country>USA</country>
        </postal>
        <email>rjbs@fastmailteam.com</email>
      </address>
    </author>

    <author initials="N." surname="Jenkins" fullname="Neil Jenkins">
      <organization abbrev="Fastmail">Fastmail Pty Ltd</organization>
      <address>
        <postal>
          <street>Level 2, 114 William Street</street>
          <city>Melbourne</city> <region>VIC</region>
          <code>3000</code> <country>Australia</country>
        </postal>
        <email>neilj@fastmailteam.com</email>
      </address>
    </author>

    <date />

    <area>ART</area>
    <workgroup>Independent Submission</workgroup>

    <keyword>Sieve</keyword>
    <abstract>
      <t>This document describes the "snooze" extension to the Sieve email
      filtering language.
      The "snooze" extension gives Sieve the ability to postpone the
      filing of an incoming into a target mailbox until a later point
      in time.</t> 
    </abstract>

    <note title="Open Issues">
      <t>
        <list style="symbols">
          <t>Should we define a new "tzid" environment item for use
          with the environment extension to obtain the time zone in
          which the interpreter is running?</t>

          <t>Should we allow :specialuse to be used with snooze? </t>

          <t>Should we allow :create to be used with snooze? </t>

          <t>What to do, if anything, about quotas?
          Do we verify that the user is under quota at the time of
          snoozing and ignore quota when awakening?</t>
        </list>
      </t>
    </note>

  </front>

  <middle>
    <section title='Introduction'>
      <t>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.</t>

      <t>This document defines a new Sieve action command "snooze"
      that postpones filing a message into a target mailbox until a
      later point in time.
      The capability string associated with this extension is
      "snooze".</t>

    </section>

    <section title='Conventions Used in This Document'>
      <t>Conventions for notations are as in Section 1.1 of <xref
      target='RFC5228'/>, including use of the "Usage:" label for the
      definition of action and tagged arguments syntax.</t>

      <t>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&nbsp;14
      <xref target='RFC2119' /> <xref target='RFC8174' /> 
      when, and only when, they appear in all capitals, as shown
      here.</t>

    </section>  <!-- Intro -->
    
    <section title='Snooze Action' anchor='snooze'>

      <figure>
        <artwork><![CDATA[
Usage: snooze [":mailbox" string]
              [":addflags" string-list] [":removeflags" string-list]
              [":weekdays" string-list]
              [":tzid" string] <times: string-list>
]]></artwork>
      </figure>

      <t>The snooze action...
      </t>

      <section title='Mailbox Argument' anchor='mailbox'>
        <t>The optional :mailbox argument is used to specify the
        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 <xref target='RFC5228' />.</t>

        <t>If :mailbox is omitted, or if the specified mailbox doesn&apos;t
        exist at the time of awakening, the message will be filed
        into the user&apos;s main mailbox.
        For instance, in an implementation where the IMAP server is
        running scripts on behalf of the user at time of delivery the
        awakened message would be filed into into the user&apos;s
        "INBOX".</t>
      </section>

      <section title='AddFlags and RemoveFlags Arguments'
               anchor='flags'>
        <t>The optional :addflags and :removeflags arguments are used
        to specify which <xref target='RFC3501'>IMAP</xref> flags
        should be added to and/or removed from the set of IMAP flags
        present on the snoozed message at the time of awakening.</t>

        <t>The general requirements for flag handling specified in
        Section 2 of <xref target='RFC5232' /> MUST be followed.</t>
      </section>

      <section title='Weekdays Argument' anchor='weekdays'>
        <t>The optional :weekdays argument specifies the set of days
        on which the specified set of awakening 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
        <xref target='RFC5260' />).</t>

        <t>If :weekdays is omitted, the set of awakening times applies
        to every day of the week.</t>
        
      </section>

      <section title='Times and TZID Arguments' anchor='times'>
        <t>The required times argument, along with the optional
        :weekdays and :tzid 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.</t>

        <t>The value of the :tzid argument MUST be a time zone
        identifier from the
        <xref target='tzdb'>IANA Time Zone Database</xref>.
        If :tzid is omitted, the time zone of the Sieve
        interpreter is used.
        </t>

        <t>The combination of the weekdays and times form a
        chronological list of awaken times.  When a message is
        snoozed, it is assigned the nearest future awaken 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.
        </t>
        
        <figure>
          <preamble>Example:</preamble>
          <artwork><![CDATA[
require ["snooze"];

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

        <t><list style='symbols'>
          <t>A message snoozed at Thu, 18 Jun 2020 00:00:00 UTC would be
          awakened at Thu, 18 Jun 2020 12:00:00 local time in Melbourne.</t>

          <t>A message snoozed at Thu, 18 Jun 2020 04:00:00 UTC would be
          awakened at Thu, 18 Jun 2020 16:00:00 local time in Melbourne.</t>

          <t>A message snoozed at Thu, 18 Jun 2020 08:00:00 UTC would be
          awakened at Fri, 19 Jun 2020 08:00:00 local time in Melbourne.</t>

          <t>A message snoozed at Fri, 19 Jun 2020 12:00:00 UTC would be
          awakened at Mon, 22 Jun 2020 08:00:00 local time in Melbourne.</t>
        </list></t>
      </section>

      <section title='Interaction with the Imap4flags Extension'
               anchor='imap4flags'>
        <t>TODO: Discuss using <xref target='RFC5232'>
        setflag/addflag/removeflag</xref> actions if
        flags are to be set on the message when snoozing.</t>
      </section>

      <section title='Interaction with the MailboxID Extension'
               anchor='mailboxid'>
        <t>TODO: Discuss using
        <xref target='I-D.gondwana-sieve-mailboxid'>:mailboxid</xref>
        rather than :mailbox.</t>
      </section>

    </section> <!-- snooze -->

    <section title='Mechanics of Snoozing Messages' anchor='snoozing'>
      <t>TODO: Stipulate that the process of snoozing is implementation
      specific and outside the scope of this document.  Possible methods:

      <list style='symbols'>
        <t>File message into to "snoozed" mailbox and then move to target
        mailbox at specifed time.</t>

        <t>Queue message for SMTP future delivery (need to worry about
        snooze loops).</t>
      </list>
      </t>
    </section> <!-- snoozing -->

    <section title="Implementation Status" anchor="impl">

      <t>&lt; RFC Editor: before publication please remove this section
	and the reference to <xref target="RFC7942"/> &gt;</t>

      <t>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 <xref target="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.</t>

	<t>According to <xref target="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".</t>

      <section title="Cyrus Server" anchor="cyrus" toc="exclude">
	<t>The open source <eref
	target="http://www.cyrusimap.org/">Cyrus Server</eref> project
        is a highly scalable enterprise mail system which supports
	Sieve email filtering at the point of final delivery.  This
        production level Sieve implementation supports all of the
        requirements described in this document.  This implementation
        is freely distributable under a BSD style license from
	<eref target="http://www.cmu.edu/computing/">
          Computing Services at Carnegie Mellon University</eref>.</t>
      </section>

    </section> <!-- Implementations -->
 
    <section title='Security Considerations' anchor='security'>
      <t>In addition to the security considerations in
      <xref target='RFC5228'/> it should be noted that:

      <list style='symbols'>
        <t>TODO: Discuss potentially going over quota before re-delivery.</t>
        <t>TODO: Discuss preventing snooze-loops if awakened messages are
        processed by Sieve.</t>
      </list>
      </t>
    </section>

    <section title='Privacy Considerations' anchor='privacy'>
      <t>This extension introduces no privacy considerations beyond
      those in <xref target='RFC5228'/>.</t>
    </section>

    <section title='IANA Considerations'>

      <section title="Registration of Sieve Extension">
	<t>
	  <list style='empty'>
	    <t>To: iana@iana.org</t>
	    <t>Subject: Registration of new Sieve extension</t>
	    <t>Capability name: snooze</t>
	    <t>Description: Adds the "snooze" action command to
            postpone filing a message into a target mailbox until a
            later point in time.</t>
	    <t>RFC number: RFC XXXX</t>
	    <t>Contact address: The Sieve discussion list
            &lt;sieve@ietf.org&gt;</t>
	  </list>
	</t>
      </section>

    </section> <!-- IANA -->
<!--
    <section title='Acknowledgments'>
      <t>The authors would like to thank the following individuals for
      contributing their ideas and support for writing this
      specification: .</t>
    </section>
-->
  </middle>

  <back>
    <references title='Normative References'>
      &rfc2119;
      &rfc3501;
      &rfc5228;
      &rfc5232;
      &rfc8174;
      &mailboxid;

      <reference anchor='tzdb'
                 target="https://www.iana.org/time-zones">
        <front>
          <title>Time Zone Database</title>
          <author>
            <organization>Internet Assigned Numbers Authority</organization>
          </author>
          <date />
        </front>
      </reference>
    </references>

    <references title='Informative References'>
      &rfc5260;
      &rfc7942;
    </references>
<!--
    <section title="Change History (To be removed by RFC Editor before
                    publication)">
      <t>Changes since draft-murchison-sieve-snooze-00:
      <list style='symbols'>
      </list>
      </t>
    </section>
-->
  </back>
</rfc>