Lots of people self-host their email, it works fine. The worst problem I've encountered is graylisting delays. Sometimes Gmail will throw a fit, but that's true

Lots of people self-host their email, it works fine. The worst problem I've encountered is graylisting delays. Sometimes Gmail will throw a fit, but that's true whether you're originating from @icloud.com or from @yourtinydomain.com. A couple years ago I did some superficial analysis on the domains of the registration emails our customers were giving us. I don't remember the details, but IIRC only about 80% of them were connected to one of the big providers (google, apple, qq, microsoft, yahoo(!), etc).