milter-greylist - Milter for greylisting, the next step in the spam control war
Greylisting is a new method of blocking significant amounts of spam at
the mailserver level, but without resorting to heavyweight statistical
analysis or other heuristical (and error-prone) approaches. Consequently,
implementations are fairly lightweight, and may even decrease network
traffic and processor load on your mailserver.
This package provides a greylist filter for sendmail's milter API.