milter-greylist

Easy-to-use greylist milter for sendmail and postfix

This is a port of Emmanuel Dreyfus' milter-greylist. Grey listing is a wonderful spam filtering technique, which uses a behavior trick: spammers never resend a message when they get a temporary error, whereas real MTA do. The idea is to refuse any mail on first attempt, and accept it after some time has elapsed. milter-greylist is a stand-alone milter written in C that implement grey listing.