Hey folks,
my sincere apologies for the confusion this has caused. I’ll start out with saying this indeed wasn’t intentional. We have recently set up some build automation that was supposed to change a symlink to point to the correct metadata, but it didn’t. Therefore when f-droid built K-9 Mail, it took the metadata from the wrong directory, and the listing was updated with the wrong content.
Despite f-droid saying an update from K-9 Mail to Thunderbird is available, you still have K-9 Mail installed (com.fsck.k9), and you will have received a K-9 Mail build as it is intended to be. Note however that K-9 Mail and Thunderbird are on the same code base, so you won’t see a major difference in functionality or looks at the moment. There are a few common complaints you might point out that are covered in various github issues that we’ll be working on smoothing out shortly.
We did an emergency build yesterday to trigger an f-droid update, and the f-droid team graciously restarted the build cycle for us. Once the cycle is through (max 2-3 days), K-9 Mail will be restored to its original listing.
In terms of future maintenance, it isn’t reasonable to say we’d maintain K-9 Mail for ever and ever, but before we make any erratic changes we’d like to see how Thunderbird evolves. For the time being, no matter if you prefer the looks of Thunderbird or K-9 Mail, you’ll be able to follow releases in either app.
The apps are built on the same code base, and there are a few features enabled in Thunderbird that don’t make sense in the context of K-9 Mail. If you’d like to have a voice in direction I’d encourage you to install Thunderbird Beta and stay in touch via the relevant channels linked in our README.