Get the beta version
You can download a beta version of the app via these channels:
We publish all of our releases there. Beta versions are marked with a “Pre-release” label.
You should be able to join the beta program using the Google Play Store app. Look out for the “Join the beta” section in K-9 Mail’s detail page.
Unlike stable versions, beta versions on F-Droid are not marked with a “Suggested” label. You have to manually select such a version to install it. To get update notification for non-suggested versions you need to check ‘Settings > Expert mode > Unstable updates’ in the F-Droid app.
To report bugs found in the beta version use K-9 Mail’s issue tracker on GitHub. Please make sure the bug hasn’t been reported before by searching existing issues, also one that have already been closed.