You could run multiple mx records if you wanted, prob don't need to tho. You'll need to make sure you have proper dns ptr record for it. I'd recommend postfix. The time consuming stuff is giving users access w imap and etc, managing users, mail formats.
Discussion
I ran my own server - it was a disaster. Deliverability to corporate emails would often get blocked. And then that block flag would get propagated to the black list of many other corporate admins.
I would never try doing this again if deliverability is important 😜