Sieve Working Group                                             B. Leiba
Internet-Draft                           IBM T.J. Watson Research Center
Expires: April 19, 2007
Intended status: Standards Track                               M. Haardt
Expires: September 8, 2007                        AG
                                                        October 16, 2006
                                                           March 7, 2007

                  Sieve Notification Mechanism: mailto

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at

   The list of Internet-Draft Shadow Directories can be accessed at

   This Internet-Draft will expire on April 19, September 8, 2007.

Copyright Notice

   Copyright (C) The Internet Society (2006). IETF Trust (2007).


   This document describes a profile of the Sieve extension for
   notifications, to allow notifications to be sent by electronic mail.

Table of Contents

   1.    Introduction . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.2.  Conventions used in this document  . . . . . . . . . . . . .  3

   2.    Definition . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.1.  Notify tag ":method" . . . . . . . . . . . . . . . . . . . .  4
   2.2.  Notify tag ":priority" . ":importance" . . . . . . . . . . . . . . . . . .  4
   2.3.  Notify tag ":message"  . . . . . . . . . . . . . . . . . . .  4
   2.4.  Other Definitions  . . . . . . . . . . . . . . . . . . . . .  5

   3.    Examples . . . . . . . . . . . . . . . . . . . . . . . . . .  7  6

   4.    Internationalization Considerations  . . . . . . . . . . . .  9  8

   5.    Security Considerations  . . . . . . . . . . . . . . . . . . 10  9

   6.    IANA Considerations  . . . . . . . . . . . . . . . . . . . . 11 10

   7.    References . . . . . . . . . . . . . . . . . . . . . . . . . 12 11
   7.1.  Normative References . . . . . . . . . . . . . . . . . . . . 12 11
   7.2.  Non-Normative References . . . . . . . . . . . . . . . . . . 12 11

         Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 13 12
         Intellectual Property and Copyright Statements . . . . . . . 14 13

1.  Introduction

1.1.  Overview

   The [Notify] extension to the [Sieve] mail filtering language is a
   framework for providing notifications by employing URIs to specify
   the notification mechanism.  This document defines how [mailto] URIs
   are used to generate notifications by e-mail.

1.2.  Conventions used in this document

   Conventions for notations are as in [Sieve] section 1.1, including
   the use of [Kwds] and the use of [ABNF].
   [[no abnf ref: We don't actually need the ABNF reference...]] [Kwds].

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [Kwds].

2.  Definition

   The mailto mechanism results in the sending of a new email message (a
   "notification message") to notify a recipient about a "triggering

2.1.  Notify tag ":method"

   The mailto notification mechanism uses standard mailto URIs as
   specified in [mailto].  URI headers with hname "from", "subject" and
   "received" are ignored if specified; all other URI headers are

   [[Barry ignored: Should we ignore them, or should their presence be
   an error?]]

   [[Michael ignored: The mailto URI spec allows for either.  I like
   ignoring them more, because it fits into the picture of ignoring a
   different sender for other message-generating actions, if it is

   [[Barry ignored 2: My thinking, when I suggested error, was that a
   script that explicitly tried to use them, even when this spec says
   "don't", would be broken.  I see no reasonable scenario through which
   the mailto URI could be derived in a computed way that would include
   those fields, and thus justify ignoring them rather than considering
   them an error.]]

2.2.  Notify tag ":priority" ":importance"

   The :priority :importance tag has no special meaning for this notification
   mechanism, and this specification puts no restriction on its use.
   Implementations MAY use the value of :priority :importance to set a priority or
   importance indication on the notification message.

2.3.  Notify tag ":message"

   o  Unless overridden by ":from", the "From:" header field and the
      envelope sender of the notification message are set either to the
      envelope "to" field from the triggering message, as used by Sieve.

      [[Barry from: It might be better in some cases for Sieve,
      or to a fixed address (so it "comes from the notification to "come from"
      system"), at the sender discretion of the triggering message.
      In other cases it might be better for all notifications to come
      from implementation.

      [[Barry sender: Alternative: the "mail system".  I think we should define a way "from" is set to specify the behaviour here, perhaps with a new notify tag.]]

      [[Michael from: Variables could perform both.  Does that

      [[Barry sender: Should we also provide a mapping or setting for envelope to,
      and the "Sender:" header field?]]

      [[Michael sender: If that "sender" is required, set to the base spec should allow
      it for all methods, like it offers ":from".]] adderss of the notification
   o  The "To:" header field and the envelope recipient(s) of the
      notification message are set to the address(es) specified in URI
      (including any URI headers where the hname is "to").

      [[Barry to: I'd like some way to specify that the To: header
      should be retained from the triggering message.  In fact, I'd like
      a way to say that ALL headers be retained.]]

      [[Michael to: Retaining the original "To:" field could easily
      result in a loop.  I think we need to define the focus of this
      method: Generic SMTP message generation, or "just notifications"
      over SMTP?]]

   o  The "Received:" field from the triggering message are retained in
      the notification message, as these may help detect and prevent
      mail loops.

   o  The "Subject:" field of the notification message contains the
      value defined by the :message notify tag, as described in
      [Notify].  If there is no :message tag, the subject is retained
      from the triggering message.  Note that Sieve [Variables] can be
      used to advantage here, as shown in the example in Section 3.

   o  All other header fields of the notification message either are as
      specified by URI headers, or have implementation-specific values;
      their values are not defined here.  It is suggested that the
      implementation capitalizes the first letter of URI headers and
      adds a space character after the colon between the mail header
      name and value when adding URI headers to the message.

   o  If the mailto URI contains a "body" header, the value of that
      header is used as the body of the notification message.  If there
      is no "body" header, the body of the notification message is

      [[Barry body: I'd like some way to specify that the body contain
      some excerpt from the body of the triggering message.]]

      [[Michael body: Can variables do that?  I don't know.]] message.  Does anyone
      else want this, or should we just say "Barry's being silly," and
      forget it?]]

2.4.  Other Definitions

   Because the receipt of an email message is generating another email
   message, implementations MUST take steps to avoid mail loops.  The
   notification message contains the "Received:" fields from the
   triggering message to allow loop detection as described in [RFC2821],
   section 6.2.  The implementation MUST allow messages with empty
   envelope senders to trigger notifications.

   [[Barry loops: We should say more about this...]]

   [[Michael loops: Ok now?  Informal reference or normative?  Could you
   add it?]]

   [[comment 1: Mailto URIs focus on the message, not its submission.
   There is no way to specify envelope parameters, require encryption or
   authentication.  Sure enough there is more than SMTP, so mailto is
   fine not to address this specific transport, but should we ever need
   more, it can not be specified as URI header, because there is no room
   in its namespace.]]

   [[comment 2: Michael tried to get documentation on SMTP-SMS gateways,
   but everybody operating one keeps the specification like a precious
   secret.  From experiments made some years ago, we know some gateways
   ignore all messages with empty envelope senders, some do not
   implement MIME and some ignore the body.]]

3.  Examples

   Triggering message (received by

      Return-Path: <>
      Received: from by
        for <>; Wed, 7 Dec 2005 05:08:02 -0500
      Received: from by
        for <>; Wed, 7 Dec 2005 02:00:26 -0800
      Message-ID: <>
      Date: Wed, 07 Dec 2005 10:59:19 +0100
      Precedence: list
      List-Id: Knitting Mailing List <>
      From: "Jeff Smith" <>
      To: "Knitting Mailing List" <>
      Subject: [Knitting] A new sweater

      I just finished a great new sweater!

   Sieve script (run on behalf of

      require ["notify", "variables"];

      if header :contains "list-id" "" {
        if header :matches "Subject" "[*] *" {
          notify :method ""
                 :message "From ${1} list: ${2}"
                 :importance "3";

   Notification message:

      Received: from by
        for <>; Wed, 7 Dec 2005 05:08:02 -0500
      Received: from by
        for <>; Wed, 7 Dec 2005 02:00:26 -0800
      Date: Wed, 7 Dec 2005 05:08:55 -0500
      Message-ID: <>
      From: <>
      To: <>
      Subject: From Knitting list: A new sweater
   Note that:

   o  Fields such as "Message-ID:" and "Date:" were generated afresh for
      the notification message, and do not relate to the triggering

   o  Additional "Received:" fields will be added to the notification
      message in transit; the ones shown were copied from the triggering

   o  If this message should appear at the server
      again, the server can use the presence of a ""
      received line to avoid sending another notification.

4.  Internationalization Considerations

   [[Internationalization: What do we say here?]]

5.  Security Considerations

   Sending a notification is comparable with forwarding mail to the
   notification recipient.  Care must be taken when forwarding mail
   automatically, to ensure that confidential information is not sent
   into an insecure environment.

   The automated sending of email messages exposes the system to mail
   loops, which can cause operational problems.  Implementations of this
   specification MUST protect themselves against mail loops.

   Additional security considerations are discussed in [Sieve] and in

6.  IANA Considerations

   [[IANA to-do: What do we need to do to actually get this set up with
   The following template specifies the IANA registration of the Sieve
   notification mechanism specified in this document:

   Subject: Registration of new Sieve notification mechanism
   Mechanism name: mailto
   Mechanism URI: draft-duerst-mailto-bis (change to RFC----)
   Mechanism-specific tags: none
   Standards Track/IESG-approved experimental RFC number: this RFC
   Person and email address to contact for further information:
       Michael Haardt <>

   This information should be added to the list of sieve notification
   mechanisms given on

7.  References

7.1.  Normative References

   [Kwds]     Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", RFC 2119, March 1997.

   [Notify]   Melnikov, A., Ed., Leiba, B., Ed., Segmuller, W., and T.
              Martin, "Sieve Extension: Notifications", work in
              progress, draft-ietf-sieve-notify, December 2005.

   [Sieve]    Guenther, P., Ed. and T. Showalter, Ed., "Sieve: An Email
              Filtering Language", work in
              progress, draft-ietf-sieve-3028bis, November 2005.

   [mailto]   Duerst, M., Masinter, L., and J. Zawinski, "The mailto URI
              scheme", work in progress, draft-duerst-mailto-bis,
              February 2005.

7.2.  Non-Normative References

   [ABNF]     Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 4234, October 2005.

   [RFC2821]  Klensin, J., Ed., "Simple Mail Transfer Protocol",
              RFC 2821, April 2001.

              Homme, K., "Sieve Extension: Variables", work in
              progress, draft-ietf-sieve-variables, October 2005.

Authors' Addresses

   Barry Leiba
   IBM T.J. Watson Research Center
   19 Skyline Drive
   Hawthorne, NY  10532

   Phone: +1 914 784 7941

   Michael Haardt AG
   Willstaetter Str. 13
   Duesseldorf, NRW  40549

   Phone: +49 241 53087 520

Full Copyright Statement

   Copyright (C) The Internet Society (2006). IETF Trust (2007).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an

Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at


   Funding for the RFC Editor function is currently provided by the
   Internet Society. IETF
   Administrative Support Activity (IASA).