It does, but only when sending messages to another Proton Mail user.
Email is inherently insecure by design.
If people want secure encrypted messages, email is not the solution.
That's interesting and I'll keep it in mind. As you say, I never really think of email of being that safe, but I liked ProtonMail seemed a bit safer along with it not being provided by a big company. I've been happy with it so far anyway.