I’ve also continued to experiment with ProtonMail. I haven’t had any real problems with either the web interface or the mobile app, so that’s good. I looked into their IMAP plans a bit more too. It looks like their plan for that is to have a “bridge” program that can run on your PC, which will encrypt/decrypt emails on the fly and interface with your desktop email program (Outlook or whatever). That’s good, I guess, but it would mean that you still wouldn’t be able to use IMAP on iOS, if I understand it correctly. I guess there’s no easy solution to that, given the way that their service is set up.