Does not run on anything other than x64. Otherwise it's perfect.

Who is running a mail server on their phone?

Probably no one, but plenty of people run services on SBCs

If you want to host email on your raspberry at home, your main issue is usually that your IP will be in a known „dial-up“ IP range, that is blocked by all major email providers. And most home internet providers block port 25 too. And you need a fixed IP, it’s a nightmare if your mail server‘s ip ever changes.

This is also a problem for ARM servers. Oracle's free tier is quite generous, especially if you use their free ARM offering (4 * 1 core with 6GB of RAM, no time limit on the free offering), but you can't run Mailcow on it.

This has been flagged on Github and the dev's response was "well, don't run anything important on a free server" and that was basically the end of that. I was pretty disappointed with that, but on the other hand there's nothing that prevents you from building the images yourself on ARM.

There's this - https://quay.io/organization/mailcowarm64

Haven't tried it

Equally happy! Would recommend!

Also a happy Mailcow user.

Only complaint would be to allow for multiple webauthn/fido2 keys per account. You can add a TOTP key to 3 yubikeys, but it's an additional hassle.