Ingo, the "Email Filter Rules Manager", started as a frontend for the Sieve
filter language, and is now a generic and complete filter rule frontend that
currently is able to create Sieve, procmail, maildrop, and IMAP filter rules.
The IMAP filter driver translates the filter rules on demand to IMAP commands,
executed via PHP's IMAP extension and has replaced IMP's internal filtering
code. It is now the default filtering agent in IMP H3 (4.x).