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 Mail cash, I guess? Not really into crypto.
@eldersea @evacide if you want to remain as anonymous as possible, you'd use the free tier and don't populate a recovery email. They had to give that to French police by way of court order, which helped the police identify the suspect.