Just in time for 10 years of Tuta/Tutanota, we are launching the most significant security upgrade of Tuta Mail with TutaCrypt. This groundbreaking post-quantum encryption protocol will secure emails with a hybrid protocol combining state-of-the-art quantum-safe algorithms with traditional algorithms (AES/ECC) making Tuta Mail the world’s first email provider that can protect emails from quantum computer attacks.
If you, a non tuta user, receive a mail from a tuta user you only get a download link. Which at least protects the content but not the metadata that someone send you an email. If a non tuta user sends a mail to a tuta user, there isn’t much tuta can do unfortunately. I’m not quite sure how you expect tuta to do magic? They do what they can.