Network Working Group                                       T. Showalter
Internet Draft: Sieve: Vacation Extension                      Mirapoint
Document: draft-showalter-sieve-vacation-04.txt           August 8, 2000
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.

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   Copyright (C) The Internet Society 2000.  All Rights Reserved.


   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.

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0. Meta-information on this draft

   This information is intended to facilitate discussion.  It will be
   removed when this document leaves the Internet-Draft stage.

0.1. Discussion

   This draft is intended to be an extension to the Sieve mail filtering
   language, avaliable from the Internet-Drafts repository as
   (where 10 is the version number, which is currently 10).

   This draft and the Sieve language itself are being discussed on the
   MTA Filters mailing list at <>.  Subscription
   requests can be sent to <> (send an
   email message with the word "subscribe" in the body).  More
   information on the mailing list along with a WWW archive of back
   messages is available at <>.

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

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

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   (that is, the envelope from address) of the message being responded

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 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 sends mail to
   roadrunner@acme, once with the subject "Cyrus bug" and once with the
   subject "come over for dinner", and roadrunner@acme has the script
   below, coyote@desert 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 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

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   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

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 section
   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.

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   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

   Implementations SHOULD NOT not to respond to any message with a
   header that begins with "List-".

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                           ["",
                "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

   Example:  require "vacation";
             if header :contains "from" "" {
                redirect "";
             } else {
                vacation "Sorry, I'm away, I'll read your message
                   when I get around to it.";

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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


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Appendix A.  References

   [IMAIL] Crocker, D., "Standard for the Format of ARPA  Internet  Text
   Messages", STD 11, RFC 822, University of Delaware, August 1982.

   [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., Work in Progress.

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

   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

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