> You can run your own mail server and name server on top. The network of mail is very much federated.

While I do completely agree with that in theory (and I also love mail) I think it does not stand the reality test because of email deliveravility which tends to be a nightmare.

How do you solve this? Do you use a third party SMTP?

I ran multiple mail servers for years until about 10 years ago (moved out of the industry). The deliverability problem, as far as I know, hasn't really changed that much in the last decade. The key was to configure DKIM, SPF, only use secure protocols and monitor the various black/block-lists to make sure you aren't on them for very long. In my experience, if you end up on a few bad lists, and don't react quickly, the reputation of your domain goes down rapidly and it's harder to get off said lists.

You also want some spam filtering, which, these days, is apparently much more powerful with local LLMs. I used to just use various bayesian classification tools, but I've heard that the current state of affairs is better. Having said that, when you've trained the tool, it does a pretty good job.

It's not "plug-and-play", but it's not that hard. Once you've got it up and running the maintenance load goes to almost zero.