story
When you’re communicating with email addresses outside of ProtonMail, their servers will see your emails. Your emails might then be encrypted “at rest”, but they’ve passed through their servers unencrypted anyway.
To workaround it, for sending to email addresses without a ProtonMail account, AFAIK they also give the possibility to send a link to a ProtonMail interface for decryption.
And also web interfaces are inherently insecure for E2E encryption, which ProtonMail encourages.
This is not how email is supposed to work.
Speaking of email ProtonMail also doesn’t work via standard IMAP and SMTP. You need an adapter to use classic mail clients and that only works on the desktop.
In other words ProtonMail is anti-standards.
And for me standards are more important than promises of privacy that an email service can’t really meet.
Unless you’re doing PGP or similar, independent of the email service being used, then email is incompatible with encryption.