I'm happy with Zoho Mail [1]. Even their free tier comes with a custom domain and 5 GB mailbox.
After evaluating the alternatives, I'm still with them (both Google and Microsoft were too expensive or didn't support what I expected), I only wish they'd been more upfront with their issues. They did write a blog post later, and I think they've learned:
https://www.zoho.com/service-updates/blog/zoho-customer-supp...