Follow-up question: Should someone interested in self-hosting do it from a literal PC in your basement, configured as a server? Or is self-hosting on AWS / DreamHost / whatever good enough? I ask because I like self-hosting a lot, especially when market solutions don’t really do what I need them to. But security, man, that worries me. I can’t tell you what a three-way handshake truly is, or what a signed certificate…
For those who feel unable top securely self host I'd suggest looking into smaller providers of hosted E-Mail solutions. A large number of federated services is better than everyone being on Google Workspace or MS360.