Network Working Group                                       Jutta Degener
Internet Draft                                             Sendmail, Inc.
Expires: October 2003                                          April 2003


                      
Sieve -- "copy" extension
                  
<draft-degener-sieve-copy-00.txt>


Status of this memo

   This document is an Internet-Draft and is subject to all
   provisions of Section 10 of RFC2026.

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Abstract

   This document defines a new keyword parameter, ":copy", to
   be used with the sieve "fileinto" and "redirect" actions.
   The new parameter prevents cancellation of the implicit keep.


. Introduction

   Some users have the notion of forwarding a copy of a message
   for safekeeping to another e-mail address, or of saving a copy
   in a folder -- in addition to the regular message delivery,
   which shouldn't be affected by the copy.

   If saving an extra copy is all the user wanted to do,

        fileinto "unfiltered";
        keep;

   would do the job.  But the explicit "keep" is a poor substitute
   for the implicit keep when more processing follows:

        fileinto "unfiltered";
        keep;

        if header "Subject" "MAKE MONEY FAST!!!"
        {
                discard;
        }

   In this example, the "discard" is ineffective against the
   explicit "keep"; the discarded message still ends up in
   the user's inbox.

   It is possibly to generate sieve code that perfectly
   expresses a user's wishes, but such code quickly grows
   unwieldy because it needs to keep track of the state
   the implicit keep would have had without the fileinto
   or redirect command.

   This extension tries to make life easier for user interface
   designers and script writers by allowing them to express
   the "copy" semantics directly.


. Conventions used.

   Conventions for notations are as in [SIEVE] section 1.1, including
   use of [KEYWORDS] and "Syntax:" label for the definition of action
   and tagged arguments syntax.

   The capability string associated with extension defined in this
   document is "copy".


. ":copy" extension to the "fileinto" and "redirect" command.

   Syntax:
        "fileinto" [:copy] <folder: string>
        "redirect" [:copy] <folder: string>

   If the optional :copy keyword is specified with "fileinto"
   or "redirect", the tagged command does not cancel the
   implicit keep.  Instead, it merely files or redirects a
   copy in addition to whatever else is happening to the
   message.


. Security Considerations

   The "copy" extension makes it easier to eavesdrop on a user's
   message stream without the user noticing.


. Acknowledgments

   Thanks to Eric Allman, Will Lee, and Rand Wacker for
   corrections and comments.


. Author's Address

   Jutta Degener
   Sendmail, Inc.
   6425 Christie Ave, 4th Floor
   Emeryville, CA 94608

   Email: jutta@sendmail.com


. Discussion

   This section will be removed when this document leaves the
   Internet-Draft stage.

   This draft is intended as an extension to the Sieve mail filtering
   language.  Sieve extensions are 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/>.



Appendices

Appendix A.  References

   [KEYWORDS]   Bradner, S., "Key words for use in RFCs to Indicate
                Requirement Levels", RFC 2119, March 1997.

   [SIEVE]      Showalter, T.,  "Sieve: A Mail Filtering Language", RFC 3028,
                January 2001.


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