Sieve Working Group B. Leiba Internet-Draft IBM T.J. Watson Research Center Expires: April 19, 2007 M. Haardt freenet.de AG October 16, 2006 Sieve Notification Mechanism: mailto draft-ietf-sieve-notify-mailto-01 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 April 19, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document describes a profile of the Sieve extension for notifications, to allow notifications to be sent by electronic mail. Leiba & Haardt Expires April 19, 2007 [Page 1] Internet-Draft Sieve Notification Mechanism: mailto October 2006 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" . . . . . . . . . . . . . . . . . . . 4 2.3. Notify tag ":message" . . . . . . . . . . . . . . . . . . . 4 2.4. Other Definitions . . . . . . . . . . . . . . . . . . . . . 5 3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4. Internationalization Considerations . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . 10 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . 11 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1. Normative References . . . . . . . . . . . . . . . . . . . . 12 7.2. Non-Normative References . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statements . . . . . . . 14 Leiba & Haardt Expires April 19, 2007 [Page 2] Internet-Draft Sieve Notification Mechanism: mailto October 2006 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...]] 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 April 19, 2007 [Page 3] Internet-Draft Sieve Notification Mechanism: mailto October 2006 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" 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: 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 forbidden.]] 2.2. Notify tag ":priority" The :priority 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 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 to the envelope "to" field from the triggering message, as used by Sieve. [[Barry from: It might be better in some cases for the notification to "come from" the sender of the triggering message. In other cases it might be better for all notifications to come from the "mail system". I think we should define a way to specify the behaviour here, perhaps with a new notify tag.]] [[Michael from: Variables could perform both. Does that suffice?]] [[Barry sender: Should we also provide a mapping or setting for the "Sender:" header field?]] [[Michael sender: If that is required, the base spec should allow it for all methods, like it offers ":from".]] Leiba & Haardt Expires April 19, 2007 [Page 4] Internet-Draft Sieve Notification Mechanism: mailto October 2006 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 empty. [[Barry body: I'd like some way to specify that the body contain the body of the triggering message.]] [[Michael body: Can variables do that? I don't know.]] 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. Leiba & Haardt Expires April 19, 2007 [Page 5] Internet-Draft Sieve Notification Mechanism: mailto October 2006 [[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.]] Leiba & Haardt Expires April 19, 2007 [Page 6] Internet-Draft Sieve Notification Mechanism: mailto October 2006 3. Examples Triggering message (received by recipient@example.org): Return-Path: Received: from mail.example.com by mail.example.org for ; Wed, 7 Dec 2005 05:08:02 -0500 Received: from hobbies.example.com by mail.example.com for ; 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 Sender: knitting-bounces@example.com Errors-To: knitting-bounces@example.com 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 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}" :priority "3"; } } Notification message: Received: from mail.example.com by mail.example.org for ; Wed, 7 Dec 2005 05:08:02 -0500 Received: from hobbies.example.com by mail.example.com for ; Wed, 7 Dec 2005 02:00:26 -0800 Date: Wed, 7 Dec 2005 05:08:55 -0500 Message-ID: From: To: <0123456789@sms.example.net> Subject: From Knitting list: A new sweater Leiba & Haardt Expires April 19, 2007 [Page 7] Internet-Draft Sieve Notification Mechanism: mailto October 2006 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. Leiba & Haardt Expires April 19, 2007 [Page 8] Internet-Draft Sieve Notification Mechanism: mailto October 2006 4. Internationalization Considerations [[Internationalization: What do we say here?]] Leiba & Haardt Expires April 19, 2007 [Page 9] Internet-Draft Sieve Notification Mechanism: mailto October 2006 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]. Leiba & Haardt Expires April 19, 2007 [Page 10] Internet-Draft Sieve Notification Mechanism: mailto October 2006 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----) 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 http://www.iana.org/assignments/sieve-notification. Leiba & Haardt Expires April 19, 2007 [Page 11] Internet-Draft Sieve Notification Mechanism: mailto October 2006 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. [Variables] Homme, K., "Sieve Extension: Variables", work in progress, draft-ietf-sieve-variables, October 2005. Leiba & Haardt Expires April 19, 2007 [Page 12] Internet-Draft Sieve Notification Mechanism: mailto October 2006 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 AG Willstaetter Str. 13 Duesseldorf, NRW 40549 Germany Phone: +49 241 53087 520 Email: michael.haardt@freenet-ag.de Leiba & Haardt Expires April 19, 2007 [Page 13] Internet-Draft Sieve Notification Mechanism: mailto October 2006 Full Copyright Statement Copyright (C) The Internet Society (2006). 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. 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