I have compiled my official mail provider recommendations. With any provider, you must always use your own domain.
Good: Down to earth. Unlimited domains, storage, etc. Full marks for philosophical, ethical, and technical merits.
Bad: Difficult to set up. UI is a bit confusing. Advertises itself in your signature in the free plan. Apparently blocks VPN and Tor users (I have reached out to them about this).
Note: Was unable to evaluate their webmail
Good: excellent PGP support and good on other security fronts as well
Bad: requires google captcha, does not handle plaintext as well as I'd like, german leaks through into the english interface sometimes, too scatterbrained
Good: Goes above and beyond in support for various standards and protocols, handles plaintext email very well. Lots of good options for account security.
Bad: rough UI
migadu is hard to set up but is the best all-around offering. If you're security concious, mailbox.org has the best PGP support and good all-around security; runbox.com has good account security options but no built-in PGP support.
Evaluated but not recommended: disroot, fastmail, posteo.de, poste.io, protonmail, tutanota, riseup, cock.li, teknik, megacorp mail (gmail, outlook, etc)
Hello! This is mas.to, a general-purpose, predominantly English-speaking instance. We're enthusiastic about Mastodon, and want to make this instance special. We've settled on a nice, short domain name, keep up-to-date with the latest Mastodon updates and features and want to make an easygoing and fun place to interact with other Mastodon users.