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
@evacide so the only real solution is to run your own mail server, because corporations will always do this if pressured?
@caitp @evacide it is not a solution because you have to pay someone to deploy your own server, such as the internet provider, or the VPS provider. The solution could be to pay corporations without a tracked method, if available.