[actualwitch]

Yes, if op wants encrypted mail there aren't many other options around, and I think there was some standard that allows proton <-> tutanota e2ee communication, but I don't remember its name.

[fckthisguy]

Proton's encryption is just PGP, so it works with any other provider out of the box.

I prefer that over proprietary solutions.

I think you can get tutanota to interop with Proton if you use Proton's relay.