RFC 3598 (rfc3598) - Page 2 of 6

Sieve Email Filtering -- Subaddress Extension

RFC 3598                 Sieve Email Filtering            September 2003


1.  Introduction

   Subaddressing is the practice of appending some "detail" information
   to the local-part of an [IMAIL] address to indicate that the message
   should be delivered to the mailbox specified by the "detail"
   information.  The "detail" information is prefixed with a special
   "separator character" (typically "+") which forms the boundary
   between the "user" (original local-part) and the "detail" sub-parts
   of the address, much like the "@" character forms the boundary
   between the local-part and domain.

   Typical uses of subaddressing might be:

   -  A message addressed to "ken+" is delivered into a
      mailbox called "sieve" belonging to the user "ken".

   -  A message addressed to "5551212#" is delivered to
      the voice mailbox number "123" at phone number "5551212".

   This document describes an extension to the Sieve language defined by
   [SIEVE] for comparing against the "user" and "detail" sub-parts of an
   address.

   Conventions for notations are as in [SIEVE] section 1.1, including
   use of [KEYWORDS].

2.  Capability Identifier

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

3.  Subaddress Comparisons

   Commands that act exclusively on addresses may take the optional
   tagged arguments ":user"  and ":detail" to specify what sub-part of
   the local-part of the address will be acted upon.

   NOTE: In most cases, the envelope "to" address is the preferred
   address to examine for subaddress information when the desire is to
   sort messages based on how they were addressed so as to get to a
   specific recipient.  The envelope address is, after all, the reason a
   given message is being processed by a given sieve script for a given
   user.  This is particularly true when mailing lists, aliases, and
   "virtual domains" are involved since the envelope may be the only
   source of detail information for the specific recipient.






Murchison                   Standards Track