> It’s a closed system (no IMAP).

That's a huge bummer :(

Does Hey support custom domains? IMAP and custom domain support would make Hey very appealing as a Fastmail replacement after Australia shot its tech industry in the foot with new surveillance regulation.

Edit: Looks like custom domain support is planned but not yet available: https://hey.com/faqs/

Edit edit: timdorr beat me to it :D