Do not, seriously. You probably read this because you’re wondering wether to sign up for an account.
Why not?
Proton isnt actually as private as you think it is.
But its end-to-end encrypted!
Its only encrypted when you send mail to other proton users, the second you send mail to @gmail.com or @outlook.com mail its as good as “unencrypted” mail.
But its open source!
The front end is FOSS, but the back end, which stores and manages your mail, is not.