ProtonMail, which claims to be a "secure e-mail service from Switzerland," supplies user data to security authorities. User data also goes to law enforcement agencies in the USA, as a current case shows.

The proceedings concern threats against, among others, the well-known immunologist Anthony Fauci. In a series of emails, the sender threatened, among other things, to kill Fauci and his family.

As the U.S. Department of Justice writes, the defendant used "an email account from a provider of secure, encrypted email services based in Switzerland."

According to the corresponding affidavit, this email service was ProtonMail. The relevant emails end accordingly with "Sent with ProtonMail Secure Email".

On the basis of data from ProtonMail, which was sent to the USA by way of legal assistance, it emerged that the defendant had used several user accounts at ProtonMail.

According to his own statements, the accused had switched to ProtonMail because he believed he was protected by Swiss data protection law and end-to-end encryption. Nevertheless, the sender could be identified in the interaction of data from ProtonMail as well as other online services.

https://steigerlegal.ch/2021/08/02/protonmail-daten-usa/

https://www.justice.gov/usao-md/press-release/file/1416926/download