[fevangelou]

I'd say Mail-in-a-Box, along with Modoboa and iRedMail, are perhaps the only serious open source email server setups right now, that are not based on Docker. Commercial ones do exist in the form of cPanel and Plesk (if you need some sort of support), although the underlying software is pretty much the same.

The only downside with MiaB is it is unnecessary complicated to update (both the software AND the server OS). This shouldn't be too hard to address in the future...

References:

https://modoboa.org/en/

https://www.iredmail.org/

[jboynyc]

There's also simple-nixos-mailserver: https://gitlab.com/simple-nixos-mailserver/nixos-mailserver

[oriettaxx]

iredmail (free version) is useless, so expect to pay

I use Ispconfig

they are both ordinary stuff, very very old style

(these all should be in docker swarm nowadays)

Ah, a great modern tool in front of ispconfig is proxmox mail gateway

[nanna]

Free iredmail makes updating extremely labourious. You have to manually update every package to each version step by step. It's a nightmare which is why the paid for version exists. I'm not opposed to paying but beware what you get yourself into.