postfix-postfwd

Postfix firewall policy daemon

The program uses the postfix policy delegation protocol to control access to the mail system before a message has been accepted (please visit http://www.postfix.org/SMTPD_POLICY_README.html for more information). It allows you to choose an action (e.g. reject, dunno) for a combination of several smtp parameters (like sender and recipient address, size or the client's TLS fingerprint).