Description:

Thunderbird is one of the most widely used desktop email clients in the open-source ecosystem. Presently, Proton Mail can only be accessed through the Bridge, and Proton Calendar cannot be used at all. This causes several limitations:

• The Bridge must always be running in the background;
• There is no native calendar support in Thunderbird;
• Reliability and performance depend on a proxy layer instead of direct protocols;

Meanwhile, Mozilla has just merged K-9 into Thunderbird as their official Android app and is developing Thundermail—a new service platform that will offer online mail, documents, spreadsheets, slides, and more. If Proton keeps relying solely on the Bridge, Thunderbird could evolve from a strong integration partner into a direct competitor.

What is needed:

• Native IMAP/SMTP support for Proton Mail in Thunderbird (using secure encrypted protocols);
• Native CalDAV support for Proton Calendar;

This would provide:

• A first-class experience without running a separate Bridge process;
• Proper calendar integration for daily use;
• A strong position before Thundermail matures into a full office suite;
• Something Google and Microsoft still do not offer: privacy-first desktop integration;

Linux support matters:

A large portion of privacy-focused users run Linux. Full support for major distributions, especially Arch Linux (where bleeding-edge versions of Thunderbird are common), would significantly improve adoption and reliability.

Why this is important:

Proton has the opportunity to become the only privacy-centric provider that integrates seamlessly with a mainstream open-source desktop client. Implementing native protocols now would prevent loss of ground later and make Proton the obvious choice for users who prefer desktop applications.

Cheers!