Open source Thunderbird email is coming to Android

Thunderbird, the open source email application, is coming to Android thanks to the K-9 Mail Android email app project, which is joining Thunderbird to become the Thunderbird Android email app. 

Two years ago Mozilla Foundation moved Thunderbird to its subsidiary MZLA Technologies Corporation in a similar ownership structure to Firefox under the foundation’s subsidiary, Mozilla Corporation. The new subsidiary allowed the Thunderbird project to plot its own path with new features like OpenPGP end-to-end encryption and a long-awaited mobile app. 

According to the Thunderbird team, talks between Thunderbird product manager Ryan Lee Sipes and K-9’s lead maintainer Christian Ketterer over a possible collaboration for a Thunderbird email app started in 2018. 

Fast forward to 2022, the two have decided the best path forward is for K-9 to simply join Thunderbird rather than Thunderbird building its own app from scratch. 

“Many Thunderbird users have asked for a Thunderbird experience on mobile, which we intend to provide by helping make K-9 amazing (and turning it into Thunderbird on Android). K-9 will supplement the Thunderbird experience and enhance where and how users are able to have a great email experience. Our commitment to desktop Thunderbird is unchanged, most of our team is committed to making that a best-in-class email client and it will remain that way,” Thunderbird said.

This means K-9 will take on the Thunderbird name and branding. But first, K-9 Mail will need to be aligned with Thunderbird’s feature set and visual appearance.      

“To accomplish that, we’ll devote finances and development time to continually improving K-9 Mail. We’ll be adding brand new features and introducing quality-of-life enhancements,” the Thunderbird team said in a blogpost.

K-9 isn’t a hugely popular email app on Google Play but has had 5 million downloads from the Google Play Store. 

The roadmap for K-9 Mail currently includes: creating account setup using Thunderbird account auto-configuration; improved folder management; support for message filters, and syncing between desktop and mobile Thunderbird.

While Thunderbird acknowledges there’s been demand for a Thunderbird app on iOS, the project only says in an FAQ that it is currently “evaluating” that option. 

The team says it remains committed to desktop Thunderbird and that K-9 Mail will be “brought in-line with Thunderbird from a feature perspective, and we will ensure that syncing between Thunderbird and K-9/Thunderbird on Android is seamless.”

The Thunderbird team also plans to offer Firefox Sync as as an option to sync accounts between Thunderbird and K-9 Mail. This should be implemented in summer 2023. 

The project is also exploring what Thunderbird features to bring to the Android app, such as support for calendars, tasks, feeds and chat.