> ProtonMail only works if you send messages to another ProtonMail user.
Your wording is not entirely accurate.
ProtonMail works perfectly well with external PGP. You can import third-party keys and IIRC it also supports WKD.
So its not "only another ProtonMail user".
IN ADDITION .... you can also send an encrypted, password protected message to a non-Proton Mail email address. The recipient can read it in the browser: https://proton.me/support/password-protected-emails
Your wording is not entirely accurate.
ProtonMail works perfectly well with external PGP. You can import third-party keys and IIRC it also supports WKD.
So its not "only another ProtonMail user".
IN ADDITION .... you can also send an encrypted, password protected message to a non-Proton Mail email address. The recipient can read it in the browser: https://proton.me/support/password-protected-emails