Beta: K-9 Mail 5.910

Changes in this version:

  • POP3: Changed the way the list of supported authentication methods is retrieved from the server
  • IMAP: Removed setting to enable remote search (it’s now enabled by default; still requires an additional button press)
  • Changed the default color for registered contacts to provide good contrast with both light and dark themes
  • Fixed search by sender name
  • Ignore spaces at the end of the username inserted by some software keyboards when using auto-completion

Read the post “How do I become a beta tester?” to learn where to get the beta version.

K-9 Mail is looking for funding. Currently 1,218 patrons are funding the project. You can join them by donating here.


I am not able to install this beta version. Neither from the google play store nor from the github repository.
It just keeps saying “K-9 Mail kann nicht installiert werden” (Could not install K-9 Mail) without further information.
Phone is a moto G60s, Android 11 (1.1.2022), Kernel 4.14.186+.
Can you please give me a hint what I can do next?
Thanks and best regards.

Did you get the one you currently have installed from fdroid, or some other repository like that? You can’t install releases with differing signing keys on top of each other. The official github and google store releases use the same key, so releases from those two sources work together, but others don’t (and the android error is vague).


thanks for answering. I installed the active version from fdroid, that’s true. So I need to uninstall the old version. Is there any solution to backup the emails?
Thanks and best regards.

I would assume that Fdroid also provides the latest Beta versions? At least 5.909 seems to be mentioned in their web page.