Proton Mail[a] is a Swiss[7] end-to-end encrypted email service co-founded in 2013 by Andy Yen.

[20] It was met with enough response that after three days they needed to temporarily suspend beta signups to expand server capacity.

PayPal stated that the account was frozen due to doubts of the legality of encryption, statements that opponents said were unfounded.

[26][27] On August 14, 2015, Proton Mail released major version 2.0, which included a rewritten codebase for its web interface.

With a new interface for the web client, version 3.0 also included the public launch of Proton Mail's iOS and Android beta applications.

[34] In September 2018, one of the suspected Proton Mail attackers was arrested by British law enforcement and charged in connection with a series of other high-profile cyberattacks against schools and airlines.

"[40] In April 2022 ProtonMail acquired SimpleLogin, a company based in Paris, France that provides email aliasing addresses.

In September 2015, Proton Mail added native support to their web interface and mobile app for PGP.

The recipient receives a link to the Proton Mail website on which they can enter the password and read the decrypted message.

[57] Proton Mail maintains data centers in three countries: Switzerland (one in Lausanne and another in Attinghausen in the former K7 military bunker under 1,000 meters (3,300 ft) of granite), Germany and Norway.

[58] Each data center uses load balancing across web, mail, and SQL servers, redundant power supply, hard drives with full disk encryption, and exclusive use of Linux and other open-source software.

In December 2014, Proton Mail joined the RIPE NCC in an effort to have more direct control over the surrounding Internet infrastructure.

[65] For this reason, the company strongly suggests that users who need to hide their identity from the Swiss government use their Tor hidden service/onion site.

[67] As a reason for the block, it cited Proton Mail's refusal to give up information relating to accounts that allegedly sent out spam with terror threats.

[73] Around August 2021, Proton complied with a court order in a case involving death threats made against immunologist Anthony Fauci.

[74] Around September 2021, Proton began logging the IP address of a French climate activist, after receiving a court order.

The conflict arose from Australia's legislation mandating companies to provide law enforcement access to encrypted communications.

Yen argued that complying would compromise the fundamental privacy and security guarantees Proton Mail offers its users.