PLEASE play nice with protonmail..
Don't make a laughing stock of tuta and proton
Just find a way to work together.
add a silly 'intermediate' level of security so that at least SOME layer of security is added when mailing to proton addresses.
It is just silly and thick headded to force insecure communication between otherwise secure platforms.
YES we get it tuta also encrypts the header. GREAT!
Now be one step more advanced and just play nice with proton.
Just place a big ass:
WARNING header is NOT encrypted when sending mail to proton.