If you pay Proton Mail for a service, they may hand over the payment data in response to a court order: https://www.404media.co/proton-mail-helped-fbi-unmask-anonymous-stop-cop-city-protestor/
Proton Mail Helped FBI Unmask Anonymous ‘Stop Cop City’ Protester

A court record reviewed by 404 Media shows privacy-focused email provider Proton Mail handed over payment data related to a Stop Cop City email account to the Swiss government, which handed it to the FBI.

404 Media
May I assume @Tutanota would be bound to do the same thing?
@ohmu @Tutanota Yes. No corporation is immune to legal compulsion.