Open source email app K-9 will soon become Thunderbird’s Android client

Something to look forward to: Mozilla’s Thunderbird has long been one of the best email clients for those that value open-source software and privacy, but it’s only been available to desktop users. Fortunately, that’s about to change. Soon, Thunderbird will be coming to Android devices thanks to a merger (of sorts) between Mozilla’s client and the K-9 Mail app.

If you’re wondering what K-9 Mail is, it’s another open source email client, much like Thunderbird. Though it doesn’t tout privacy as one of its key features, it boasts several others — support for Push IMAP, white and dark themes, message flagging, and the ability to set up ‘multiple identities’ for email accounts, to name a few.

As for why Thunderbird is absorbing K-9 Mail now — seemingly out of the blue — it turns out that these plans were set in motion years ago. Way back in 2018, in fact. At the time, Thunderbird Product Manager Ryan Lee Sipes met with K-9 project maintainer Christian Ketterer to discuss a collaboration between K-9 and Thunderbird. Those talks eventually evolved into a more robust discussion about how the two separate projects might join forces to create an “awesome, seamless email experience across platforms.”

For Ketterer and Sipes, that doesn’t mean developing an entirely new mobile client jointly — but instead simply making Thunderbird their collective focus.

As such, at some point in the hopefully not-too-distant future, K-9 will turn into Thunderbird’s Android client. The branding will change, and both the aesthetic and featureset will be altered to match Thunderbird’s desktop counterpart.

It will take a lot of hard work from the Thunderbird team and K-9’s contributors to reach that point, of course. However, now that Ketterer has joined the Thunderbird crew full-time, the transition should be a bit smoother. At any rate, we can’t wait to see Thunderbird make the leap to Android, and we hope it happens sooner rather than later.