Postfix Greylisting Policy Server
This package is based on the package 'postgrey' from project 'home:wberrier'.
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.