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 I guess in theory you could find a service that will shut down before complying (ala 2013 Lavabit), but I can't imagine there are many of them at any given time because, well, they'll shut down (by design) on a frequent basis. Not sure if better or worse than the headache of running it yourself. @evacide