Thunderbird is taking over a beloved open-source email app to transform it into its own mobile client

Thunderbird forays into smartphones by taking over a beloved open-source app

Thunderbird is an email client that’s older than most TikTok users and it has definitely seen brighter days. The client itself still looks straight out of 2003. So when its development team announced that the client was going to make its way to smartphones, we were intrigued to say the least. Could this be the boost Thunderbird needs to go back to its golden era? Thunderbird has just unveiled what it’s planning to do as part of its grand entrance into smartphones. It involves the K-9 Mail app and it’s excellent news for open-source as well as productivity enthusiasts.

Mozilla has obtained the trademark rights and source code of K-9 Mail, including its GitHub repo. This means that Thunderbird will essentially be built upon the tried-and-true K-9 app that many open-source evangelists are already familiar with. To make for a smooth transition, K-9 Mail’s project maintainer, Christian Ketterer (also known as cketti) is joining the Thunderbird staff. Down the road, once certain development goals have been met in terms of looks and features (like synchronization between mobile and desktop, Thunderbird account auto-configuration, and support for message filters), K-9 Mail will be rebranded as Thunderbird.


If you want to help shape the future of Thunderbird on mobile, the team encourages you to install K-9 Mail on your Android phone now. It’ll undergo a lot of changes before it actually becomes Thunderbird, and the development team is going to need help and testing over that process. Of course, with the app being fully open-source, you can check out how things are going in K-9 Mail’s GitHub repository. Firefox Sync for synchronization between desktop Thunderbird and K-9 is expected to arrive by summer 2023, so the app might look a lot more Thunderbird-like by that point.

The company says it may want build out an iOS client from scratch as it’s more difficult to pick up an existing FOSS solution there. It also doesn’t want to compromise on approach mobile with native code instead of libraries for cross-platform development.

Make sure to check out K-9 Mail in the Google Play Store, or on F-Droid. Hold off from installing it if you don’t want to deal with frequent interface changes potentially disrupting your workflow over and over, though.

As to the desktop client, Thunderbird is due for another anniversary update on June 28 which will have smoothed out most of the cruft in its large code base and give it a new look as well as an import/export tool between computers.

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