I decided to self-host my mail a few weeks ago and ran through all of the big names I'd heard - Mailcow, mailinabox, Stalwart, and Dovecot+Postfix; honestly I didn't like any of them. Stalwart is very corpo, hard to configure (reading the docs[0] confused the shit out of me), and feels vibe-coded. Mailcow and miab push a huge stack onto you in a way that feels hard to modify yourself, e.g. expecting you to allocate ~2GB ram(?) to running ClamAV, and I never managed to get Dovecot+Postfix working properly.
In the end I paved over my Linux VM with OpenBSD and used Dovecot+OpenSMTPD which I found dead simple and so far faultless. I have nothing but kind words for it.
That's fair. It is perfectly reasonable to want customizability if control is what you are after. I remember the days fondly where I was running postfix and dovecot on bare metal.
Nowadays my interests have skewed towards being able to have groupware features without much maintenance so groupware in a box suits my needs just fine. The learning curve to doing serious customization with a large FOSS groupware project might be a bit longer but that is offset by other factors.
Yeah I definitely get less done on OpenBSD, but I have more fun doing it, and fortunately in my position where that works for me. If I were providing a service to others instead of just myself I'd have to rethink my stack.