> They cannot provide end-to-end encrypted mail because limitations in existing email protocols prevent it. All they can do is quickly wrap the contents of your

> They cannot provide end-to-end encrypted mail because limitations in existing email protocols prevent it. All they can do is quickly wrap the contents of your mail in encryption once it has arrived. Based on my understanding, that claim is for people who use ProtonMail to email other ProtonMail users. In that situation, emails are indeed end-to-end encrypted, without you having to encrypt the email content yourself, first.