Postfix Greylisting Policy Server
This package is based on the package 'postgrey' from project 'server:mail'.
Postgrey is a Postfix policy server implementing greylisting.
When a request for delivery of a mail is received by Postfix
via SMTP, the triplet CLIENT_IP / SENDER / RECIPIENT is built.
If it is the first time that this triplet is seen, or if the
triplet was first seen less than 5 minutes, then the mail gets
rejected with a temporary error. Hopefully spammers or viruses
will not try again later, as it is however required per RFC.
The following features compared with greylist.pl from Postfix 2.1.1
Safe database, automatic maintenance, whitelists, lookup by subnet,
auto-whitelisting of clients, only Berkeley DB and no large mysql
nor postgresql DB needed.