Package postfwd

https://postfwd.org/

Postfwd is written in Perl to combine complex Postfix restrictions in a
ruleset similar to those of the most firewalls. The program uses the
Postfix policy delegation protocol to control access to the mail system
before a message has been accepted. It allows 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).

Version: 2.03