Ask HN: Alternative to Proton Mail?

So I wanted to get away from GMail because I don't want to depend on a service that could just go away at any moment. Now I need to get away from Proton because they can't keep the air conditioners in Franfurt running.

What are the alternatives people are trying? I would like to have:

a. A service that can run for a week without going down for hours at a time.

b. Custom domains. Ideally I would like all messages to a particular domain routed to my in-home server with an online web-mail interface for the last couple of months.

c. Don't barf on PGP or S/MIME.

d. IMAP or POP. If I can't just get simple message routing to/from my local server, I'll take IMAP (preferably) and POP (if I have to.)

e. A service that can run for a week without going down for hours at a time.

I guess I get what I deserve. The "S" in "ProtonMail" is for "Service Level Agreement."