Just pushed my current status to

  https://github.com/darklajid/ansible-communication

Careful though: This isn't deployed outside of test machines yet. I'm still working on the proper backup/restore scenarios, consider a couple improvements etc. - the readme outlines what I would like to do next.

Plus: While I self-host my mails for a while (without an automated setup of sorts, the one off snowflake sort of thing, so quite different from this here), I don't claim to be an expert here. Check what I did, take it as a template, don't use it without a basic understanding.

If there are some postfix/dovecot gurus out here and would like to point out obvious flaws in my setup - go ahead!