@Jain @icedquinn @Mr_NutterButter They complied with non-Swiss court orders in the past. Just look at their transparency report from 2018.
https://web.archive.org/web/20181020170954/https://protonmail.com/blog/transparency-report/
If you look at their new transparency report, they don't even offer descriptions anymore, and they comply more than they resist, so who knows what it truly going on.
ProtonMail has other flaws. For one, if you want to end-to-end encrypt your emails using PGP/GPG, you can't provide your own keys. ProtonMail generates them server side using your password. The only person who should have access to your private keys is you.
Mr_NutterButter is right that no email service is truly private as you can never know what they are truly doing unless you have physical access to the server, but I wouldn't trust ProtonMail just because of these two flaws.
My recommendation would be to use fedora.email which is run by @sjw (registrations are currently disabled but maybe you can PM him if you want an account) or posteo.de, which is a paid service (1 EUR/month and accepts cash-by-mail like Mullvad VPN) and allows third-party mail clients and using your own GPG keys.