

You can run your own mail servers no problem. Takes about 15 minutes to get going at its simplest level. Now, there’s a whole bunch of problems you’ll run into as soon as you open it to the internet, but that’s a separate topic.
If you just want to use a custom domain: register any domain, find a mail host that supports custom domains (most do with a paid subscription), and setup your DNS records to point to wherever that service is. Now you have mail coming to “[email protected]”
















Y’all, it’s Git.
If you’re so paranoid that literally no PaaS is doing it for you, AND you don’t care about the extra features for community interaction, just push to literally any other machines to keep copies.
If you need the public facing features, and you claim they are all terrible, make your own, or STFU already, my God. It’s all UI on top of git. All those extra features ARE the product.