postfwd binary package in Ubuntu Bionic s390x

 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 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).

Source package