Curious if you looked into other mail server options? I mean Postfix (not Postgres) easily handles the load of a single user, but it is still rather hard to configure and modify.
I recently started to work with Haraka and even thought its ment for high traffic use cases i wont ever look back to Postfix (not Postgres).
Postfix is super easy, and well documented for normal use cases.
In any case you should ask the author, as they are currently active on another discussion where they linked their article in a comment: https://news.ycombinator.com/item?id=16238501#16238845
>perlgod: I've spent years tweaking my mail server setup (Postfix, Dovecot, RSPAMD, LDAP...) and did a full writeup a few months ago. I've used other guides online but found most of the rest lacking on details
And yes, damn it. Fixed