I am a very happy customer of mailbox.org ( https://mailbox.org/en/ https://mailbox.org/en/ ) It's not so obvious but they also support using your own domain.

I am a very happy customer of mailbox.org ( https://mailbox.org/en/ https://mailbox.org/en/ ) It's not so obvious but they also support using your own domain. Good but not super fast support and for me the most important thing, they support active sync so you get push on mobiles.