• Millions of Thunderbird desktop users can soon expect to see an official Thunderbird app for Android.
  • The Thunderbird team is also planning to offer Firefox Sync as an option to sync accounts between K-9 Mail and Thunderbird.

Open-source email application, Thunderbird, is coming to Android with the help of the K-9 Mail Android email app project. K-9 Mail is joining Thunderbird to become the Thunderbird Android email app. This is a part of the Thunderbird revival.

The Thunderbird app is incredibly lightweight compared to modern, Electron-based email clients. It is also highly customizable, backed by an enthusiastic community and has a solid 19-year track record for user privacy – features quite desirable in 2022, which is why Thunderbird has grabbed Mozilla’s attention.

A new business plan, some recent updates and a considerable influx of cash hold the potential to make Thunderbird’s desktop client respectable again. But Thunderbird needs to make its mobile debut to fast-track this plan of action.

To achieve this, Mozilla has obtained the rights to K-9 Mail, an open-source email client that aligns with Thunderbird’s mission. Mozilla has opted not to build a Thunderbird app from scratch. Instead, it will transform K-9 Mail into Thunderbird for Android. It will offer most features that are admired, such as message filters, customization, account auto-configuration, and syncing with the desktop client.

Mozilla plans to slowly update K-9 Mail with Christian Ketterer, who currently maintains the app. Once it has some essential features, such as desktop syncing, K-9 Mail will be renamed “Thunderbird for Android.” The rebranding is expected to happen sometime in 2023.

It is not yet known how the K-9 Mail app will be updated in terms of features and the UI. Mozilla hopes to bring Thunderbird to iOS, though it’s focusing on Android first.

The Thunderbird-K-9 Mail collaboration

According to the Thunderbird team, Ryan Lee Sipes, Thunderbird product manager and Christian Ketterer started to talk about a possible collaboration for a Thunderbird email app in 2018. After four years, in 2022, Sipes and Ketterer have decided that the best path for the collaboration would be for K-9 to join Thunderbird rather than Thunderbird building its app from scratch.

According to Thunderbird, “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 can 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.”

This implies that K-9 will adopt the Thunderbird name and branding. But as a first step, K-9 Mail must integrate with Thunderbird’s feature set and graphical interface.

Thunderbird team wrote in a blog post, “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 is also planning to offer Firefox Sync as an option to sync accounts between K-9 Mail and Thunderbird. This will be implemented sometime in the summer of 2023. The project also explores what Thunderbird features to bring to the Android app, such as support for feeds, calendars, tasks and chat.