Network Working Group T. Showalter Internet Draft: Sieve: Vacation Extension Mirapoint Document: draft-showalter-sieve-vacation-05.txt 12 May 2003 Expire in six months Sieve: Vacation Extension Status of this memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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 Copyright Copyright (C) The Internet Society 2003. All Rights Reserved. Abstract This document describes an extension to the Sieve mail filtering language for an autoresponder similar to that of the Unix "vacation" command for replying to messages with certain safety features to prevent problems. Showalter Expire in Six Months [Page 1]
Internet DRAFT Sieve: Vacation Extension 12 May 2003 1. Introduction This is an extension to the Sieve language defined by [SIEVE] for notification that messages will not be immediately answered. Conventions for notations are as in [SIEVE] section 1.1. The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", "CAN", and "MAY" in this document are to be interpreted as defined in [KEYWORDS]. 2. Capability Identifier Sieve implementations that implement vacation have an identifier of "vacation" for use with the capability mechanism. 3. Vacation Action Syntax: vacation [":days" number] [":addresses" string-list] [":subject" string] [":mime"] <reason: string> The "vacation" action implements a vacation autoresponder similar to the vacation command available under many versions of Unix. Its purpose is to provide correspondents with notification that the user is away for an extended period of time and that they should not expect quick responses. "Vacation" is used to respond to a message with another message. Vacation's messages are always addressed to the Return-Path address (that is, the envelope from address) of the message being responded to. 3.1. Days Parameter The ":days" argument is used to specify the period in which addresses are kept and are not responded to, and is always specified in days. The minimum value used for this parameter is 1. Sites MAY define a different minimum value. Sites MAY also define a maximum days value, which MUST be greater than 7, and SHOULD be greater than 30. If ":days" is omitted, the default value is either 7 or the minimum value (as defined above), whichever is greater. If the parameter given to ":days" is less than the minimum value, then the minimum value is used instead. If ":days" exceeds the site-defined maximum, the site-defined Showalter Expire in Six Months [Page 2]
Internet DRAFT Sieve: Vacation Extension 12 May 2003 maximum is used instead. 3.2. Previous Response Tracking "Vacation" keeps track of all of the addresses that it has responded to in some period (as specified by the :days optional argument). If vacation has not previously responded to this address within that time period, it sends the "reason" argument to the Return-Path address of the message that is being responded to. Vacation responses are not just per address, but are per address per vacation command. For instance, If coyote@desert.example.org sends mail to roadrunner@acme.example.com, once with the subject "Cyrus bug" and once with the subject "come over for dinner", and roadrunner@acme.example.com has the script below, coyote@desert.example.org would receive two responses, once with the first message, once with the second. Example: require "vacation"; if subject :contains "cyrus" { vacation "I'm out -- send mail to cyrus-bugs"; } else { vacation "I'm out -- call me at 304 555 1212"; } Note that coyote@desert.example.org gets the second message despite having gotten the first one because separate vacation responses have been triggered. This behavior is REQUIRED. If a sieve script changes, implementations MAY reset the records of who has been responded to and when they have been responded to. Alternatively, implementations can store records of who has received which message, perhaps by storing a hash of the message and the recipient. 3.3. Subject Parameter Users can specify the subject of the reply with the ":subject" parameter. If the :subject parameter is not supplied, then the subject is generated as follows: The subject is set to the characters "Re: " followed by the original subject with all leading occurrence of the characters "Re: " stripped off. 3.4. MIME Parameter The ":mime" parameter, if supplied, specifies that the reason string is, in fact, a MIME part, including MIME headers (see Showalter Expire in Six Months [Page 3]
Internet DRAFT Sieve: Vacation Extension 12 May 2003 section 2.4.2.4 of [SIEVE]). If the optional :mime parameter is not supplied, the reason string is considered to be a UTF-8 string. 3.5. In-Reply-To Replies MUST have the In-Reply-To field set to the Message-ID of the original message. 3.6. Address Parameter and Limiting Replies to Personal Messages "Vacation" MUST NOT respond to a message unless the user's email address is in the "To", "Cc", or "Bcc" line of the original message. Implementations are assumed to know the user's email address, but users may have additional addresses beyond the control of the local mail system. Users can supply additional mail addresses that are theirs with the ":addresses" argument, which takes a string-list listing additional addresses that a user might have. These addresses are considered in addition to the addresses that the implementation knows. 3.7. Restricting Replies to Automated Processes and Mailing Lists Implementations MUST have a list of addresses that "vacation" MUST NOT send mail to. However, the contents of this list are implementation defined. The purpose of this list is to stop mail from going to addresses used by system daemons that would not care if the user is actually reading her mail. Implementations are encouraged, however, to include well-known addresses like "MAILER-DAEMON", "LISTSERV", "majordomo", and other addresses typically used only by automated systems. Additionally, addresses ending in "-request" or beginning in "owner-", i.e., reserved for mailing list software, are also suggested. Implementors may take guidance from [MAILBOXNAMES], but should be careful. Some addresses, like "POSTMASTER", are generally actually managed by people, and people do care if the user is going to be unavailable. Implementations SHOULD NOT not to respond to any message with a header that begins with "List-". Showalter Expire in Six Months [Page 4]
Internet DRAFT Sieve: Vacation Extension 12 May 2003 3.8. Interaction with Other Sieve Actions Vacation does not affect the implicit keep. Vacation can only be executed once per script. If vacation is used with another vacation, the script fails. Implementations MUST NOT consider vacation used with discard, keep, fileinto, or redirect an error. 3.9. Examples Here is a simple use of vacation. Example: require "vacation"; vacation :days 23 :addresses ["tjs@example.edu", "ts4z@landru.example.edu"] "I'm away until October 19. If it's an emergency, call 911, I guess." ; By mingling vacation with other rules, users can do something more selective. Example: require "vacation"; if header :contains "from" "boss@example.edu" { redirect "pleeb@isp.example.org"; } else { vacation "Sorry, I'm away, I'll read your message when I get around to it."; } 4. Security Considerations It is critical that implementations correctly implement the limitations described above. Replies MUST NOT be sent out in response to messages not sent directly to the user, and replies MUST NOT be sent out more often than the :days argument states. 5. Author's Address Tim Showalter Mirapoint, Inc. 909 Hermosa Court Sunnyvale, CA 94085 E-Mail: tjs@mirapoint.com Showalter Expire in Six Months [Page 5]
Internet DRAFT Sieve: Vacation Extension 12 May 2003 Appendix A. References [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, Harvard University, March 1997. [MAILBOXNAMES] Crocker, D. "Mailbox Names for Common Services, Roles, and Functions", RFC 2142, Internet Mail Consortium, May, 1997. [MIME] Freed, N., and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, Innosoft and First Virtual, November 1996. [SIEVE] Showalter, T., "Sieve: A Mail Filtering Language", Mirapoint, Inc., RFC 3028, January, 2001. Appendix B. Full Copyright Statement Copyright (C) The Internet Society 2000. All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS 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. Showalter Expire in Six Months [Page 6]
