A few weeks ago you might have read that the Thunderbird project is working on a mobile email client. Some of you have mentioned that it might have been a better strategy to support one of the existing open source email clients on Android rather than creating a new one. As you may have guessed from the title of this post, the Thunderbird project came to the same conclusion.

I’m very excited to announce that K-9 Mail is now part of the Thunderbird family 🎉

The conversation about how Thunderbird on desktop and K-9 Mail on Android could better work together had been going on since 2018. Our visions for an improved mobile app were more or less identical. Both projects share the same core values: privacy, open standards, and an open development process. And so it was a very easy decision to work together.

The roadmap for the near future includes improved account setup using Thunderbird account auto-configuration, improved folder management, support for message filters, and synchronization between the mobile app and Thunderbird on the desktop.

Once a certain level of functionality is reached, K-9 Mail will transform into Thunderbird on Android, and will be renamed accordingly.

Changes for existing K-9 Mail users

As a user of K-9 Mail, there’s nothing you have to do right now. Just continue to use the app and enjoy it getting better over time.

If you want to help shape the app, please continue to provide bug reports, feature requests, and general feedback. For discussions about the future of the app we’ve created the Thunderbird Android Planning Topicbox group.

Changes for the project

Thunderbird is now the legal home of K-9 Mail. Consequently, all donations previously going to K-9 now go to the Thunderbird project. In turn Thunderbird will ensure the app is developed further. As a first step Thunderbird hired the current K-9 Mail maintainer, cketti (coincidentally, also the author of this blog post 👋). Hopefully, more will follow soon.

In the coming weeks and months we’ll move some things around. The source code repository will be moved to the Thunderbird organization on GitHub. The app on Google Play will be moved to a different publisher account. The forum might be combined with the one Thunderbird is using for the desktop app.

Looking forward

I’ve been contributing to K-9 Mail for 12 years, and I’m more excited about the future of the app than I’ve ever been before. I hope you all are excited as well.


If you have questions or comments, please let us know in this forum thread.