There are some decent packages out there like MailCow, Mailu, there's another one for Docker, but it escapes me. I've tried, and failed. From what I understand, it takes a level of dedication.

Tbh was quite painless for me! Had a few hiccups but it was educational to troubleshoot them, and once it's up and running, I haven't had to touch it for the most part. Had to update my Dovecot configs when they changed the config syntax but that's all I can think of. And will probably see about switching from spamassassin to rspamd because I swear spamassassin has so many false positives no matter how many false positives I feed to it to train it. But it's really not so bad, and I would recommend it as a decent learning opportunity for folks who like tinkering with computers.