Sieve Working Group                                             B. Leiba
Internet-Draft                           IBM T.J. Watson Research Center
Intended status: Standards Track                               M. Haardt
Expires: September 8, 2007                                 freenet.de AG
                                                           March January 7, 2008                                      freenet AG
                                                            July 6, 2007

                  Sieve Notification Mechanism: mailto
                   draft-ietf-sieve-notify-mailto-02
                   draft-ietf-sieve-notify-mailto-03

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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   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 parameter "method"  . . . . . . . . . . . . . . . . .  4
   2.2.  Notify tag ":method" ":from" . . . . . . . . . . . . . . . . . . . . .  4
   2.2.
   2.3.  Notify tag ":importance" . . . . . . . . . . . . . . . . . .  4
   2.3.
   2.4.  Notify tag ":options"  . . . . . . . . . . . . . . . . . . .  4
   2.5.  Notify tag ":message"  . . . . . . . . . . . . . . . . . . .  4
   2.4.
   2.6.  Other Definitions  . . . . . . . . . . . . . . . . . . . . .  5

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

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

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

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

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

         Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 12
         Intellectual Property and Copyright Statements . . . . . . . 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].

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   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
   message".

2.1.  Notify tag ":method" parameter "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
   accepted.

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

   [[Michael ignored:

2.2.  Notify tag ":from"

   The mailto URI spec allows for either.  I like
   ignoring them more, because it fits into :from tag overrides the picture of ignoring a
   different default sender for other message-generating actions, if it is
   forbidden.]]

   [[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 of 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. notification
   message.

2.3.  Notify tag ":importance"

   The :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 :importance to set a priority or
   importance indication on the notification message.

2.3.

2.4.  Notify tag ":options"

   This tag is not used by the mailto method.

2.5.  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,
      or to a fixed address (so it "comes from the notification
      system"), at the discretion of the implementation.

      [[Barry sender: Alternative: the "from" is set to the envelope to,
      and the "sender" is set to the adderss of the notification
      system?]]

   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").

   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  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, it is up to the implementation to leave the
      body empty or use an excerpt of the original message.

   o  URI headers with hname "received" are considered unsafe and are
      ignored if specified.  URI headers with hname "from" and "subject"
      conflict with the implictly set values from and are ignored if
      specified.

   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
      empty.

      [[Barry body: I'd like some way to specify that the body contain
      some excerpt from the body of the triggering message.  Does anyone
      else want this, or should we just say "Barry's being silly," and
      forget it?]]

2.4.

2.6.  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.

   [[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.]]

3.  Examples

   Triggering message (received by recipient@example.org):

      Return-Path: <knitting-bounces@example.com>
      Received: from mail.example.com by mail.example.org
        for <recipient@example.org>; Wed, 7 Dec 2005 05:08:02 -0500
      Received: from hobbies.example.com by mail.example.com
        for <knitting@example.com>; Wed, 7 Dec 2005 02:00:26 -0800
      Message-ID: <1234567.89ABCDEF@example.com>
      Date: Wed, 07 Dec 2005 10:59:19 +0100
      Precedence: list
      List-Id: Knitting Mailing List <knitting.example.com>
      Sender: knitting-bounces@example.com
      Errors-To: knitting-bounces@example.com
      From: "Jeff Smith" <jeff@hobbies.example.com>
      To: "Knitting Mailing List" <knitting@example.com>
      Subject: [Knitting] A new sweater

      I just finished a great new sweater!

   Sieve script (run on behalf of recipient@example.org):

      require ["notify", "variables"];

      if header :contains "list-id" "knitting.example.com" {
        if header :matches "Subject" "[*] *" {
          notify :method "mailto:0123456789@sms.example.net" :message "From ${1} list: ${2}"
                 :importance "3"; "3"
                 "mailto:0123456789@sms.example.net";
        }
      }

   Notification message:

      Received: from mail.example.com by mail.example.org
        for <recipient@example.org>; Wed, 7 Dec 2005 05:08:02 -0500
      Received: from hobbies.example.com by mail.example.com
        for <knitting@example.com>; Wed, 7 Dec 2005 02:00:26 -0800
      Date: Wed, 7 Dec 2005 05:08:55 -0500
      Message-ID: <A2299BB.FF7788@example.org>
      From: <recipient@example.org>
      To: <0123456789@sms.example.net>
      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
      message.

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

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

4.  Internationalization Considerations

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

   This specification introduces no specific internationalization issues
   that are not already addressed in [Sieve] and in [Notify].

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
   [Notify].

6.  IANA Considerations

   [[IANA to-do: What do we need to do to actually get this set up with
   IANA?]]

   The following template specifies the IANA registration of the Sieve
   notification mechanism specified in this document:

   To: iana@iana.org
   Subject: Registration of new Sieve notification mechanism
   Mechanism name: mailto
   Mechanism URI: draft-duerst-mailto-bis (change to RFC----) RFC2368
   Mechanism-specific tags: none
   Standards Track/IESG-approved experimental RFC number: this RFC
   Person and email address to contact for further information:
       Michael Haardt <michael.haardt@freenet-ag.de>

   This information should be added to the list of sieve notification
   mechanisms given on
   http://www.iana.org/assignments/sieve-notification.

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.,   Hoffman, P., Masinter, L., and J. Zawinski, "The mailto URI
              URL scheme", work in progress, draft-duerst-mailto-bis,
              February 2005. RFC 2368, July 1998.

7.2.  Non-Normative References

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

   [Variables]
              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
   US

   Phone: +1 914 784 7941
   Email: leiba@watson.ibm.com

   Michael Haardt
   freenet.de
   freenet AG
   Willstaetter Str. 13
   Duesseldorf, NRW  40549
   Germany

   Phone: +49 241 53087 520
   Email: michael.haardt@freenet-ag.de michael.haardt@freenet.ag

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