Sieve Email Filtering -- Subaddress Extension
obsoleted by
- rfc-5233 — Sieve Email Filtering: Subaddress Extension
Extracted elements (10)
The mechanisms used to define and/or query the separator character used by the mail system are explicitly out of scope for this document, acknowledging that different mail systems use different separator conventions (e.g., '+', '#').
The envelope 'to' address is the preferred address to examine for subaddress information when sorting messages by recipient, especially when mailing lists, aliases, and virtual domains are involved, since the envelope may be the only source of detail information for the specific recipient.
Implementations MUST ensure that the separator character matches that used and/or allowed by the encompassing mail system to avoid unexpected results.
Implementations SHOULD allow the separator character to be configurable so that the extension may be used with a variety of mail systems.
The ADDRESS-PART syntax element from [SIEVE] is augmented to include ':user' and ':detail': ADDRESS-PART =/ ':user' / ':detail'.
The ':detail' argument specifies the sub-part of the local-part to the right of the separator character (e.g., 'sieve' in 'ken+[email protected]'). If no separator exists the test evaluates to false; if nothing lies to the right of the separator, ':detail' ':is' the null key ('').
The 'subaddress' extension adds optional tagged arguments ':user' and ':detail' to Sieve address-handling commands, allowing comparison against sub-parts of the local-part of an email address separated by a special separator character (typically '+').
The ':user' argument specifies the sub-part of the local-part to the left of the separator character (e.g., 'ken' in 'ken+[email protected]'). If no separator exists, ':user' specifies the entire local-part, equivalent to ':localpart'.
This document registers the Sieve extension capability named 'subaddress' (keyword: subaddress, arguments: N/A) in the IANA list of Sieve extensions at http://www.iana.org/assignments/sieve-extensions.
Security considerations are inherited from [SIEVE] (RFC 3028). The subaddress extension is believed not to introduce any additional security concerns beyond those already present in the base Sieve specification.