does anyone have a good suggestion for running a mail server on my nixos box?
The one thing I’ll never recommend anyone selfhost is email. It’s just plain not worth it.
You can do literally everything right and still get cucked by spam filters because you’re not a recognized email provider.
It’s not Nix-specific, but I use Mailcow-dockerized and it is completely hassle-free, been using it for 4 or 5 years now without a bobble (though I’ve run my own mailserver for 30 years).
I would agree that a static IP is necessary, but I don’t have one and I get by, even without a PTR record. That’s probably due to a fairly small ISP with not many spammers having found it.
Make sure you set up your DKIM and DMARC right from the start and pay heed to the reports. But I’ve never had to fight to get off a blacklist, even with new domains I’ve added to it.
Self hosting email is a difficult business.
The main issue is that you must have a static IP and that IP needs to have a good mail reputation or you will be blacklisted in a few days.
Said so, Today there are pretty good selfhostable email stacks like stalwart
My solution, which has been running for over two decades, is bare metal with postfix, dovecot, opendkim, opendmarl, spamassassin and a few more poeces which are all absolutely mandatory. Plus a nice webmail and a few more optional pieces.
But on gentoo, not on nix
I run Postfix, Dovecot and rspamd on my server. The configuration is here: https://git.dblsaiko.net/systems/tree/configurations/polaris
There’s also the Simple NixOS Mailserver project which is an abstraction on top of these and has a few more things. I’ve never used it myself though.
Of course, you also have to set up all the standard email setup like DKIM, DMARC, SPF and so on here.
