The case for boring mail servers
Reasonable people disagree about running your own mail. This is the best version of the argument I’ve read for doing it anyway:
The interesting parts of a mail server are solved. What’s left is the boring part — keys that rotate, backups that restore, a dashboard someone actually looks at — and the boring part is the whole job. If you don’t want the boring part, you don’t want a mail server; you want an inbox. That’s fine. But be honest about which one you’re paying for.
I’d add: pick the software with the fewest moving parts you don’t understand. For me that turned out to be Stalwart.