Sieve Working Group B. Leiba
Internet-Draft IBM T.J. Watson Research Center
Intended status: Standards Track M. Haardt
Expires: September 19, 2008 freenet AG
March 18, 2008
Sieve Notification Mechanism: mailto
draft-ietf-sieve-notify-mailto-07
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-
Drafts.
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
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 19, 2008.
Copyright Notice
Copyright (C) The IETF Trust (2008).
Leiba & Haardt Expires September 19, 2008 [Page 1]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
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. Test notify_method_capability . . . . . . . . . . . . . . 4
2.3. Notify tag ":from" . . . . . . . . . . . . . . . . . . . . 4
2.4. Notify tag ":importance" . . . . . . . . . . . . . . . . . 4
2.5. Notify tag ":options" . . . . . . . . . . . . . . . . . . 4
2.6. Notify tag ":message" . . . . . . . . . . . . . . . . . . 4
2.7. Other Definitions . . . . . . . . . . . . . . . . . . . . 5
2.7.1. The Auto-Submitted header field . . . . . . . . . . . . . 7
3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 8
4. Internationalization Considerations . . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . 12
6.1. Registration of notification mechanism . . . . . . . . . . 12
6.2. New registry for Auto-Submitted header field keywords . . 12
6.3. Initial registration of Auto-Submitted header field
keywords . . . . . . . . . . . . . . . . . . . . . . . . . 12
7. References . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Normative References . . . . . . . . . . . . . . . . . . . 14
7.2. Non-Normative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . 15
Intellectual Property and Copyright Statements . . . . . . 16
Leiba & Haardt Expires September 19, 2008 [Page 2]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
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].
Leiba & Haardt Expires September 19, 2008 [Page 3]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
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 parameter "method"
The mailto notification mechanism uses standard mailto URIs as
specified in [mailto].
2.2. Test notify_method_capability
The notify_method_capability test for "online" may return "yes" or
"no" only if the Sieve processor can determine with certainty whether
or not the recipients of the notification message are online and
logged in. Otherwise, the test returns "maybe" for this notification
method.
2.3. Notify tag ":from"
The :from tag overrides the default sender of the notification
message. "Sender", here, refers to the value used in the [RFC2822]
"From" header. Implementations MAY also use this value in the
[RFC2821] "MAIL FROM" command (the "envelope sender"), or they may
prefer to establish a mailbox that receives bounces from notification
messages.
2.4. 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 (perhaps a visual
indication, or perhaps making use of one of the non-standard but
commonly used message headers).
2.5. Notify tag ":options"
This tag is not used by the mailto method.
2.6. Notify tag ":message"
The value of this tag, if it is present, is used as the subject of
the notification message, and overrides all other mechanisms for
determining the subject (as described below). Its value SHOULD NOT
normally be truncated, though it may be sensible to truncate an
excessively long value.
Leiba & Haardt Expires September 19, 2008 [Page 4]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
2.7. 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 REQUIRED inclusion of an "Auto-Submitted:" field,
as described in the message composition guidelines, will also help in
loop detection and avoidance.
Implementations MUST NOT trigger notifications for messages
containing "Auto-Submitted:" header fields with any value other than
"No".
Implementations MUST allow messages with empty envelope senders to
trigger notifications.
Because this notification method uses a store-and-forward system for
delivery of the notification message, the Sieve processor should not
have a need to retry notifications. Therefore, implementations of
this method SHOULD use normal mechanisms for submitting SMTP messages
and for retrying the initial submission. Once the notification
message is submitted, implementations MUST NOT resubmit it, as this
is likely to result in multiple notifications, and increases the
danger of message loops.
The overall notification message is composed using the following
guidelines (see [RFC2822] for references to message header fields):
o If the envelope sender of the triggering message is empty, the
envelope sender of the notification message MUST be empty as well,
to avoid message loops. Otherwise, the envelope sender of the
notification message SHOULD be set to the value of the ":from"
parameter to the notify action, if one is specified, has email
address syntax and is valid according to the implementation
specific security checks (see Section 3.3 of [Notify]). If
":from" is not specified or is not valid, the envelope sender of
the notification message SHOULD be set either to the envelope "to"
field from the triggering message, as used by Sieve, or to a fixed
email address (so it "comes from the notification system"), at the
discretion of the implementation. This may not be overridden by a
"from" URI header, and any such URI header MUST be ignored.
o The header field "Auto-Submitted: sieve-notify" MUST be included
in the notification message (see Section 2.7.1). This is to
reduce the likelihood of message loops, by tagging this as an
automatically generated message. Among other results, it will
cause the notification message not to generate further
Leiba & Haardt Expires September 19, 2008 [Page 5]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
notifications. mailto URI headers with hname "auto-submitted" are
considered unsafe and MUST be ignored.
o The "From:" header field of the notification message SHOULD be set
to the value of the ":from" parameter to the notify action, if one
is specified, has email address syntax and is valid according to
the implementation specific security checks (see Section 3.3 of
[Notify]). If ":from" is not specified or is not valid, the
"From:" header field of the notification message SHOULD be set
either to the envelope "to" field from the triggering message, as
used by Sieve, or to a fixed email address (so it "comes from the
notification system"), at the discretion of the implementation.
This may not be overridden by a "from" URI header, and any such
URI header MUST be ignored.
o The "To:" header field and the envelope recipient(s) of the
notification message SHOULD be set to the address(es) specified in
the URI (including any URI headers where the hname is "to").
o The "Subject:" field of the notification message MUST contain the
value defined by the :message notify tag, as described in
[Notify]. If there is no :message tag and there is a "subject"
header on the URI, then that value SHOULD be used. If that is
also absent, the subject SHOULD be 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 SHOULD be used as the body of the notification message. If
there is no "body" header, it is up to the implementation whether
to leave the body empty or to use an excerpt of the original
message.
o The "Received:" fields from the triggering message MAY be retained
in the notification message, as these may help detect and prevent
mail loops. The "Auto-Submitted" header field MUST be placed
above these (see Section 2.7.1). URI headers with hname
"received" are considered unsafe, and will be ignored.
o Other header fields of the notification message that are normally
related to an individual new message (such as "Message-ID" and
"Date") are generated for the notification message in the normal
manner, and MUST NOT be copied from the triggering message. Any
URI headers with those names MUST be ignored. Further, the "Date"
header serves as the notification timestamp defined in [Notify].
o All other header fields of the notification message either are as
specified by URI headers, or have implementation-specific values;
Leiba & Haardt Expires September 19, 2008 [Page 6]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
their values are not defined here. It is suggested that the
implementation capitalize the first letter of URI headers and add
a space character after the colon between the mail header name and
value when adding URI headers to the message, to be consistent
with common practice in email headers.
2.7.1. The Auto-Submitted header field
The header field "Auto-Submitted: sieve-notify" MUST be included in
the notification message (see [RFC3834]). The "Auto-Submitted"
header field is considered a "trace field", similar to "Received"
header fields (see [RFC2821]). If the implementation retains the
"Received" fields from the triggering message (see above), the "Auto-
Submitted" field MUST be placed above those "Received" fields,
serving as a boundary between the ones from the triggering message
and those that will be part of the notification message.
The sieve-notify Auto-Submitted field MAY include one or both of the
following OPTIONAL parameters:
o owner-email - specifies an email address of the owner of the Sieve
script that generated this notification. If specified, it might
be used to identify or contact the script's owner. The parameter
attribute is "owner-email", and the parameter value is a quoted
string containing an email address, as defined by "addr-spec" in
[RFC2822]. Example:
Auto-Submitted: sieve-notify; owner-email="me@example.com"
o owner-token - specifies an opaque token that the administrative
domain of the owner of the Sieve script that generated this
notification can identify the owner with. This might be used to
allow identification of the owner while protecting the owner's
privacy. The parameter attribute is "owner-token", and the
parameter value is as defined by "token" in [RFC3834]. Example:
Auto-Submitted: sieve-notify; owner-token=af3NN2pK5dDXI0W
Leiba & Haardt Expires September 19, 2008 [Page 7]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
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 :message "From ${1} list: ${2}"
:importance "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>
Auto-Submitted: sieve-notify; owner-email="recipient@example.org"
From: recipient@example.org
To: 0123456789@sms.example.net
Subject: From Knitting list: A new sweater
Leiba & Haardt Expires September 19, 2008 [Page 8]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
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 recognize that. The Auto-Submitted header field
is also present to tell the server to avoid sending another
notification, and it includes an optional owner-email parameter
for identification.
Leiba & Haardt Expires September 19, 2008 [Page 9]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
4. Internationalization Considerations
This specification introduces no specific internationalization issues
that are not already addressed in [Sieve] and in [Notify].
Leiba & Haardt Expires September 19, 2008 [Page 10]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
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 (see
Section 2.7).
Additional security considerations are discussed in [Sieve] and in
[Notify].
Leiba & Haardt Expires September 19, 2008 [Page 11]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
6. IANA Considerations
6.1. Registration of notification mechanism
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: 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>
This information should be added to the list of sieve notification
mechanisms given on
http://www.iana.org/assignments/sieve-notification.
6.2. New registry for Auto-Submitted header field keywords
Because [RFC3834] does not define a registry for new keywords used in
the Auto-Submitted header field, we define one here, to be created as
http://www.iana.org/assignments/auto-submitted-keywords. This
defines the template to be used to register new keywords.
To: iana@iana.org
Subject: Registration of new auto-submitted header field keyword
Keyword value: [the text value of the field]
Description: [a brief explanation of the purpose of this value]
Parameters: [list any keyword-specific parameters, specify their
meanings, specify whether they are required or optional; use "none"
if there are none]
Standards Track/IESG-approved experimental RFC number: [identifies
the specification that defines the value being registered]
Contact: [name and email address to contact for further information]
6.3. Initial registration of Auto-Submitted header field keywords
The following are the initial keywords to be registered for the Auto-
Submitted header field, to be entered in
http://www.iana.org/assignments/auto-submitted-keywords.
Keyword value: no
Description: Indicates that a message was NOT automatically
generated, but was created by a human. It is the equivalent to the
absence of an Auto-Submitted header altogether.
Leiba & Haardt Expires September 19, 2008 [Page 12]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
Parameters: none
Standards Track/IESG-approved experimental RFC number: RFC3834
Contact: Keith Moore <moore@cs.utk.edu>
Keyword value: auto-generated
Description: Indicates that a message was generated by an automatic
process, and is not a direct response to another message.
Parameters: none
Standards Track/IESG-approved experimental RFC number: RFC3834
Contact: Keith Moore <moore@cs.utk.edu>
Keyword value: auto-replied
Description: Indicates that a message was automatically generated as
a direct response to another message.
Parameters: none
Standards Track/IESG-approved experimental RFC number: RFC3834
Contact: Keith Moore <moore@cs.utk.edu>
Keyword value: sieve-notify
Description: Indicates that a message was generated by a Sieve
notification system.
Parameters: owner-email, owner-token. Both optional, both refer to
the owner of the Sieve script that generated this message. See the
relevant RFC for details.
Standards Track/IESG-approved experimental RFC number: this RFC
Contact: Michael Haardt <michael.haardt@freenet.ag>
Leiba & Haardt Expires September 19, 2008 [Page 13]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
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.
[RFC2822] Resnick, P., Ed., "Internet Message Format", RFC 2822,
April 2001.
[RFC3834] Moore, K., "Recommendations for Automatic Responses to
Electronic Mail", RFC 3834, August 2004.
[Sieve] Guenther, P., Ed. and T. Showalter, Ed., "Sieve: An Email
Filtering Language", work in
progress, draft-ietf-sieve-3028bis, November 2005.
[mailto] Hoffman, P., Masinter, L., and J. Zawinski, "The mailto
URL scheme", 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.
Leiba & Haardt Expires September 19, 2008 [Page 14]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
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 AG
Willstaetter Str. 13
Duesseldorf, NRW 40549
Germany
Phone: +49 241 53087 520
Email: michael.haardt@freenet.ag
Leiba & Haardt Expires September 19, 2008 [Page 15]
Internet-Draft Sieve Notification Mechanism: mailto March 2008
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
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
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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
http://www.ietf.org/ipr.
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
ietf-ipr@ietf.org.
Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
Leiba & Haardt Expires September 19, 2008 [Page 16]
