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 My reading and understanding of this, is that the Swiss govt order came from an MLAT request from the FBI, and not a US court warrant. Thus, the issue, to me, is how US law enforcement essentially uses MLAT to bypass what in the US could be withheld without an appropriate judicial review. Maybe I’m projecting a misunderstanding, but when I had to respond to such requests, in the ISP I ran, we would, generally, only comply with a legal warrant or order authorized by a court.
@steff A lot of people use Proton Mail because they think its location in Switzerland gives their data greater legal protections than it might have in the US or the EU. In some cases, this may be true, but as you can see in this example, these protections are not absolute.
@evacide Exactly. There’s an odd assumption that simply offshoring services increases privacy or anonymity when the reality is that it may leave one more exposed to the global panopticon. Certainly, I think there are other questions here about how Proton’s operational policies are not optimized to protect anonymity; yet, I feel it’s important to understand that maintaining security and privacy goes far beyond simply choosing a ‘secure provider’, but requires ongoing diligence to mitigate your operational and legal risks.