Sieve Working Group A. Melnikov, Ed. Internet-Draft Isode Limited Expires: December 25, 2006 B. Leiba, Ed. W. Segmuller IBM T.J. Watson Research Center T. Martin Mirapoint Inc. June 23, 2006 Sieve Extension: Notifications draft-ietf-sieve-notify-03 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 December 25, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract Users go to great lengths to be notified as quickly as possible that they have received new mail. Most of these methods involve polling to check for new messages periodically. A push method handled by the final delivery agent gives users quicker notifications and saves Melnikov, et al. Expires December 25, 2006 [Page 1] Internet-Draft Sieve Extension: Notifications June 2006 server resources. This document does not specify the notification method but is expected that using existing instant messaging infrastructure such as Zephyr, Jabber, or SMS messages will be popular. This draft describes an extension to the Sieve mail filtering language that allows users to give specific rules for how and when notifications should be sent. ToDo o Change tagged :method to the positional parameter? Changes since draft-ietf-sieve-notify-02 o Added :from tagged argument. o Added Extract_text action, which allows to extract content of the first text/* part. o Added back the ":options" parameter to the notify action. o Added new section talking about requirements on notification method specs. o Added more examples. Changes since draft-ietf-sieve-notify-00 o Updated references, etc. o Added IANA considerations section. o Removed denotify action. o Updated examples to use the variables extension. o Replaced notification method with URI. o Removed text suggesting that this extension can be used to track all Sieve actions taken. o Changed priority to be a string. o Added text about URI verification. o Clarified that a notification method is allowed to perform adaptation of notification context (e.g. truncation, charset Melnikov, et al. Expires December 25, 2006 [Page 2] Internet-Draft Sieve Extension: Notifications June 2006 conversion, etc.). These adaptations must be documented in a document describing the notification method. o Clarified that notify is compatible with all existing actions. o Removed the :id parameter to the notify action. o Added valid_notif_method test that allows to test if an notification method (URI) is supported. o Added a new capability response to ManageSieve that allows to report supported notification types. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1.1. Conventions used in this document . . . . . . . . . . . . . 5 2. Capability Identifier . . . . . . . . . . . . . . . . . . . 5 3. Notify Action . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Notify Action Syntax and Semantics . . . . . . . . . . . . . 5 3.2. Notify tag ":method" . . . . . . . . . . . . . . . . . . . . 5 3.3. Notify tag ":from" . . . . . . . . . . . . . . . . . . . . . 6 3.4. Notify tag ":priority" . . . . . . . . . . . . . . . . . . . 6 3.5. Notify tag ":options" . . . . . . . . . . . . . . . . . . . 7 3.6. Notify tag ":message" . . . . . . . . . . . . . . . . . . . 7 3.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.8. Requirements on notification methods specifications . . . . 9 4. Extract_text Action . . . . . . . . . . . . . . . . . . . . 10 5. Test valid_notif_method . . . . . . . . . . . . . . . . . . 11 6. Interactions with Other Sieve Actions . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . 11 8. Extensions to ManageSieve protocol . . . . . . . . . . . . . 12 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 12 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 11.1. Normative References . . . . . . . . . . . . . . . . . . . . 12 11.2. Informative References . . . . . . . . . . . . . . . . . . . 13 Melnikov, et al. Expires December 25, 2006 [Page 3] Internet-Draft Sieve Extension: Notifications June 2006 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 14 Intellectual Property and Copyright Statements . . . . . . . 15 Melnikov, et al. Expires December 25, 2006 [Page 4] Internet-Draft Sieve Extension: Notifications June 2006 1. Introduction This is an extension to the Sieve language defined by [Sieve] for providing instant notifications. It defines the new action "notify". This document does not dictate the notification method used. Examples of possible notification methods are Zephyr and Jabber. The available methods shall be site-defined. 1.1. Conventions used in this document Conventions for notations are as in [Sieve] section 1.1, including the use of [ABNF]. 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. Capability Identifier The capability string associated with the extension defined in this document is "notify". 3. Notify Action 3.1. Notify Action Syntax and Semantics Usage: notify [":method" string] [":from" string] [":priority" <"1" / "2" / "3">] [":options" 1*(string-list / number)] [":message" string] The Notify action specifies that a notification should be sent to the user. The format of the notification is implementation-defined and is also affected by the notification method used (see Section 3.2). However, all content specified in the :message parameter SHOULD be included. 3.2. Notify tag ":method" The :method tag identifies the notification method that will be used; it is a URI. For example, the notification method can be an SMS URI [SMS-URI] containing a phone number, or an XMPP [XMPP] URI containing a Jabber identifier [XMPP-URI]. If the :method tag is not specified, a default implementation-defined notification method is used, and if Melnikov, et al. Expires December 25, 2006 [Page 5] Internet-Draft Sieve Extension: Notifications June 2006 there is no default method defined, the notification is ignored. Implementations MUST NOT generate an error condition for lack of a default notification method, and execution of the script MUST continue. The supported URI values will be site-specific. If an URI schema is specified that the implementation does not support, the notification MUST cause an error condition. Sieve scripts can check the supported methods using the "valid_notif_method" test to be sure that they only use supported ones, to avoid such error conditions. If the :method tag contains a supported URI schema, then the URI MUST be checked for syntactic validity. An invalid URI syntax or an unsupported URI extension MUST cause an error. An implementation MAY enforce other semantic restrictions on URIs -- for example an SMS URI can only contain phone numbers in a particular geographical region. Violation of such semantic restrictions MUST be treated as an error. [[Barry 1: "MUST" seems silly here, since the whole sentence is a "MAY".]] 3.3. Notify tag ":from" A ":from" parameter may be used to specify a notification method specific author of the notification. Implementations SHOULD check the syntax according to the notification method specification and generate an error when a syntactically invalid ":from" parameter is specified. 3.4. Notify tag ":priority" The :priority tag specifies the importance of the notification. The :priority tag is followed by a numeric value represented as a string: "1" (high importance), "2" (normal importance), and "3" (low importance). If no priority is given, a default priority of "2" SHOULD be assumed. Some notification methods allow users to specify their state of activity (for example "busy" or "away from keyboard"). If the notification method provides this information it SHOULD be used to selectively send notifications. If, for example, the user marks herself as "busy", a notification method can require that a notification with a priority of "3" is not to be sent, however the user should be notified of a higher priority notifications. If the notification method allows users to filter messages based upon certain parameters in the message, users SHOULD be able to filter based upon priority. If the notification method does not support priority, then this parameter MUST be ignored. [[Alexey 1: Should we keep using "high", "normal" and "low" instead? Numbers are easier to compare with comparators.]] [[Barry 3.5: Why do we call this "priority", and then explain it as "importance"? Shouldn't we just call it "importance"?]] Melnikov, et al. Expires December 25, 2006 [Page 6] Internet-Draft Sieve Extension: Notifications June 2006 3.5. Notify tag ":options" The :options tag is used to send additional parameters to the notification method. Interpretation of :options is method-specific. [[Alexey 2: Do we need IANA registry for this?]] 3.6. Notify tag ":message" The :message tag specifies the message data to be included in the notification. The entirety of the string SHOULD be sent but implementations MAY shorten the message for technical or aesthetic reasons. If the message parameter is absent, a default message containing the value of the From header field [[Alexey 3: Align with usage of :from]] and the value of the Subject header field will be used. Note that the notification method (the ":method" tag) may affect how this information is formatted. The implementation of a notification method MAY modify the final notification text -- for example, truncating it if it exceeds a length limit, or modifying characters that can not be represented in the target character set. Allowed modifications should be documented in a standards-track or informational document. In order to construct more complex messages the notify extension can be used together with the Sieve variables extension [Variables], as shown in the examples below. 3.7. Examples Melnikov, et al. Expires December 25, 2006 [Page 7] Internet-Draft Sieve Extension: Notifications June 2006 Example 1: require ["notify", "fileinto", "variables"]; if header :contains "from" "boss@example.org" { notify :priority "1" :message "This is probably very important"; # Don't send any further notifications stop; } if header :contains "to" "sievemailinglist@example.org" { # :matches is used to get the value of the Subject header if header :matches "Subject" "*" { set "subject" "${1}"; } # :matches is used to get the value of the From header if header :matches "From" "*" { set "from" "${1}"; } notify :priority "3" :message "[SIEVE] ${from}: ${subject}"; fileinto "INBOX.sieve"; } Example 2: require ["notify", "fileinto", "variables", "envelope"]; if header :matches "from" "*@*.example.org" { # :matches is used to get the MAIL FROM address if envelope :all :matches "from" "*" { set "env_from" " [really: ${1}]"; } # :matches is used to get the value of the Subject header if header :matches "Subject" "*" { set "subject" "${1}"; } # :matches is used to get the address from the From header if address :matches :all "from" "*" { set "from_addr" "${1}"; } notify :message "${from_addr}${env_from}: ${subject}"; } Melnikov, et al. Expires December 25, 2006 [Page 8] Internet-Draft Sieve Extension: Notifications June 2006 Example 3: require ["notify", "variables"]; set "notif_method" "xmpp:tim@example.com?You%20got%20mail&subject=SIEVE"; if header :contains "subject" "Your dog" { set "notif_method" "sms:+14085551212"; } if header :contains "to" "sievemailinglist@example.org" { set "notif_method" ""; } if not string :is "${notif_method}" "" { notify :method "${notif_method}"; } if header :contains "from" "boss@example.org" { # :matches is used to get the value of the Subject header if header :matches "Subject" "*" { set "subject" "${1}"; } # don't need high priority notification for # a 'for your information' if not header :contains "subject" "FYI:" { notify :method "sms:+14085551212" :priority "1" :message "BOSS: ${subject}"; } } [[anchor2: Make sure that the XMPP notification syntax is correct.]] 3.8. Requirements on notification methods specifications This section describes requirements on a document describing a Sieve notification method. [[Alexey 4: The whole section is very raw and needs more work.]] A notification method MAY ignore parameters specified in the Notify action. It is RECOMMENDED that a timestamp be included in the notification. Implementations SHOULD NOT include extraneous information. If there are errors sending the notification, the Sieve interpreter Melnikov, et al. Expires December 25, 2006 [Page 9] Internet-Draft Sieve Extension: Notifications June 2006 SHOULD ignore the notification and not retry indefinitely. 4. Extract_text Action Usage: extract_text [MODIFIER] [":first" number] The Extract_text action stores at most :first bytes of the first text/* part in the variable identified by varname. If the :first parameter is not present, the whole content of the first text/* part is stored. If the message being processed doesn't contain any text/* part, the action will set the variable identified by varname to empty string. [[Alexey 5: Do we need to be more specific about what "the first text part" means?]] Modifiers are applied on the extracted text before it is stored in the variable. See [Variables] for details. Note that this action is only available when the Sieve script specifies both "variables" [Variables] and "notify" capabilities in the require statements. Example 4: require ["notify", "variables"]; if header :contains "from" "boss@example.org" { # :matches is used to get the value of the Subject header if header :matches "Subject" "*" { set "subject" "${1}"; } # extract the first 100 bytes of the first text/* part extract_text :first 100 "msgcontent"; # don't need high priority notification for # a 'for your information' if not header :contains "subject" "FYI:" { notify :method "sms:+14085551212" :priority "1" :message "BOSS: ${subject}; ${msgcontent}"; } } Melnikov, et al. Expires December 25, 2006 [Page 10] Internet-Draft Sieve Extension: Notifications June 2006 5. Test valid_notif_method Usage: valid_notif_method The "valid_notif_method" test is true if the notification methods listed in the notification-uris argument are supported and they are syntactically and semantically (including implementation-specific semantic restrictions) valid. This test MUST perform exactly the same validation as would be performed on the ":method" parameter of the "notify" action. All of the listed notification methods must be supported and valid or the test is false. Example 5: if not valid_notif_method ["mailto:", "http://gw.example.net/notify?test"] { stop; } 6. Interactions with Other Sieve Actions The notify action is compatible with all other actions, and does not affect the operation of other actions. In particular, the notify action MUST NOT cancel the implicit keep. Multiple executed notify actions are allowed. 7. Security Considerations Security considerations are discussed in [Sieve]. Additionally, implementations must be careful to follow the security considerations of the specific notification methods. The notify action is potentially very dangerous. The path the notification takes through the network may not be secure. An error in the options string may cause the message to be transmitted to someone it was not intended for, or may expose information to eavesdroppers. Just because a notification is received doesn't mean it was sent by the Sieve implementation. It might be possible to forge notifications with some notification methods. Melnikov, et al. Expires December 25, 2006 [Page 11] Internet-Draft Sieve Extension: Notifications June 2006 8. Extensions to ManageSieve protocol A ManageSieve [ManageSieve] server that supports the "notify" extension MUST advertise the NOTIFY capability, that has a single mandatory parameter. The parameter is a string containing space separated list of URI schema parts for supported nofication methods. Example: S: "NOTIFY" "xmpp mailto" 9. IANA Considerations The following template specifies the IANA registration of the notify Sieve extension specified in this document: To: iana@iana.org Subject: Registration of new Sieve extension Capability name: notify Capability keyword: notify Capability arguments: N/A Standards Track/IESG-approved experimental RFC number: this RFC Person and email address to contact for further information: Alexey Melnikov This information should be added to the list of sieve extensions given on http://www.iana.org/assignments/sieve-extensions. 10. Acknowledgements Thanks to Larry Greenfield, Sarah Robeson, Tim Showalter, Cyrus Daboo, Nigel Swinson, Kjetil Torgrim Homme, Michael Haardt, Mark E. Mallett and Ned Freed for help with this document. 11. References 11.1. Normative References [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 4234, October 2005. [Kwds] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [ManageSieve] Martin, T. and A. Melnikov, "A Protocol for Remotely Melnikov, et al. Expires December 25, 2006 [Page 12] Internet-Draft Sieve Extension: Notifications June 2006 Managing Sieve Scripts", work in progress, draft-martin-managesieve, February 2006. [Sieve] Guenther, P. and T. Showalter, "Sieve: An Email Filtering Language", work in progress, draft-ietf-sieve-3028bis, July 2005. [Variables] Homme, K., "Sieve Extension: Variables", work in progress, draft-ietf-sieve-variables, October 2005. 11.2. Informative References [SMS-URI] Wilde, E. and A. Vaha-Sipila, "URI scheme for GSM Short Message Service", work in progress, draft-wilde-sms-uri, August 2005. [XMPP] Saint-Andre, Ed., P., "Extensible Messaging and Presence Protocol (XMPP): Core", RFC 3920, October 2004. [XMPP-URI] Saint-Andre, P., "Internationalized Resource Identifiers (IRIs) and Uniform Resource Identifiers (URIs) for the Extensible Messaging and Presence Protocol (XMPP)", work in progress, draft-saintandre-xmpp-iri, September 2005. Melnikov, et al. Expires December 25, 2006 [Page 13] Internet-Draft Sieve Extension: Notifications June 2006 Authors' Addresses Alexey Melnikov (editor) Isode Limited 5 Castle Business Village 36 Station Road Hampton, Middlesex TW12 2BX UK Email: Alexey.Melnikov@isode.com Barry Leiba (editor) IBM T.J. Watson Research Center 19 Skyline Drive Hawthorne, NY 10532 US Phone: +1 914 784 7941 Email: leiba@watson.ibm.com Wolfgang Segmuller IBM T.J. Watson Research Center 19 Skyline Drive Hawthorne, NY 10532 US Phone: +1 914 784 7408 Email: werewolf@us.ibm.com Tim Martin Mirapoint Inc. 909 Hermosa Court Sunnyvale, CA 94085 US Phone: +1 409 720 3835 Email: tmartin@mirapoint.com Melnikov, et al. Expires December 25, 2006 [Page 14] Internet-Draft Sieve Extension: Notifications June 2006 Intellectual Property Statement 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. 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Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Melnikov, et al. Expires December 25, 2006 [Page 15]