Network Working Group T

Network Working Group T. Showalter

Internet Draft: Sieve: Vacation Extension Mirapoint

Document: draft-showalter-sieve-vacation-04.txt August 8, 2000

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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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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.

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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

<ftp://ftp.ietf.org/internet-drafts/draft-showalter-sieve-10.txt>

(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 <ietf-mta-filters@imc.org>. Subscription

requests can be sent to <ietf-mta-filters-request@imc.org> (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 <http://www.imc.org/ietf-mta-filters/>.

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

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(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 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

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 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.

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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

unavailable.

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 ["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.";

}

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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

E-Mail: tjs@mirapoint.com

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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

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.

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