> ProtonMail to ProtonMail emails are e2ee. Emails sent outside of ProtonMail ecosystem can still be secured with a password with a link to the email hosted at

> ProtonMail to ProtonMail emails are e2ee. Emails sent outside of ProtonMail ecosystem can still be secured with a password with a link to the email hosted at ProtonMail. You can also encrypt emails with PGP with someone's public key from within ProtonMail, in this scenario you don't need to send them a password or a link. They do however have to have you in their address book with public key attached.