I can second using AWS SES, which I've built on for inbound (pretty solid) and outbound (still a work in progress) email for about a dozen domains now. My needs are very-much automation focused, so perhaps not main-stream but more developer oriented. This kind of solution keeps the data in your hands, is _very_ inexpensive to run, has some respect for privacy and compliance like GDPR, and is essentially maintenance free.

[1] https://github.com/mlhpdx/email-delivery [2] https://github.com/mlhpdx/email-origin