I use a simpler approach, I have iRedMail installed, and set it up to blacklist all recipients by default with the handy tool that came with iRedMail called wblist_admin.py..

So using the tool, first blacklist all recipients and then whitelist the one's I trust/allow..this way, I can turn off all the spam features on the mail server as I know the whitelist sources are clean..

So now, the mail server just runs Postfix, Dovecot and Nginx but I have Nginx disabled and only enable it when I want to do administrative tasks from the frontend..

NOTE: This only works on a personal self-hosted email server :>