Qmail Support Forum

admin · Site Admin Joined: 21 Jun 2005 Posts: 209

TMDA is an open source software application designed to significantly reduce the amount of spam (Internet junk-mail) you receive. TMDA strives to be more effective, yet less time-consuming than traditional spam filters. TMDA can also be used as a general purpose local mail delivery agent to filter, sort, deliver and dispose of incoming mail.

challenge/response: allows unknown senders which aren't on the whitelist or blacklist the chance to confirm that their message is legitimate (non-spam).

http://tmda.sourceforge.net/