I've been self-hosting (using a server at home) using MailInABox ( https://mailinabox.email ) for around 5 years.

I've been very happy with it. I have a perfectly normal email service, over which I have full control. MailInABox handles all the necessary DKIM etc. I had minor hassles, when I first started, with sending to google and microsoft, but these were reasonably easily managed by following microsoft's advice. (And I have a good ISP.)

The only hassle is that, because MailInABox uses greylisting, initial account-validation emails are sometimes delayed. But because I have control of the service, I can whitelist anything important :)