Check & filter outgoing mails in Postfix

Question

I am looking for a way to check outgoing mails with rules like :

• mails sent to a particular domain
• mails sent without subject or with a specific subject
• mails with an attachment of a certain size
• mails sent to x recipients

What I want to do when a mail is recognised by one of these rules could be to send it to a special address, to save it with smtp-sink or return a special message.

Is this possible to do this check and apply an action within postfix or a couple of scripts called by postfix ?

Answer 1

You could combine your Postfix setup with some other mail server dealing with the logic, like Lamson, a mail handling framework written/configurable in Python. See its documentation on the FSM logic, and the getting started.