Comment by MYEUHD
> Email can be secure, it’s just that the big US players can’t or won’t agree to proton like privacy.
Protonmail is not standards compilant. You can't login to your protonmail account from Thunderbird or k9 mail. Yes, they have an IMAP bridge, but it's proprietary / requires a paid account. Thus you're locked in to the official protonmail clients
Have you seen this thing?
https://github.com/ProtonMail/proton-bridge
I'm not too familiar with it, but we're building Marco (https://marcoapp.io) and a customer just showed it to me recently.