FreeBSD mail server: Basic SMTP with OpenSMTPd

I run mail servers for many years now, but I was never brave enough to set up one from scratch for my daily mail. So I always fell back to pre-configured solutions like docker-mailserver, Mailcow, or in case of FreeBSD to iRedMail. My biggest pain point was the secure configuration of Postfix. When I discovered OpenSMTPd, I decided that it’s the right time now to finally build a fully-featured mail server setup from scratch including virtual users, spam filter etc.