New release: K-9 Mail 5.807

Changes in 5.807:

  • POP3: Changed the way the list of supported authentication methods is retrieved from the server

This fixes the problem when accessing GMX,, and IONOS accounts via POP3.

We’re doing a staged rollout on Google Play. So it might be a few days before the new version becomes available to you. It usually takes a couple of days for new releases to show up on F-Droid. The official APK can be downloaded here: K-9 Mail 5.807.

Please note that K-9 Mail is looking for funding. Currently 1,136 patrons are funding the project. You can join them by donating here.

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I’m very sorry, but I’m on 5.807 and the problem with GMX is not fixed for me, I’m still getting “-ERR too many errors” for SSL/TLS. I would try the usual Android routine of uninstall / delete cache / reinstall, but I suppose this would wipe my database, which I would prefer to avoid. Any ideas?

Works fine for me. Please double check that you’re using 5.807 (under Settings → About → Version).

If you’re still seeing an error, please record a debug log. See LoggingErrors · k9mail/k-9 Wiki · GitHub

Since this update I can no longer send to with the previously working settings of STARTTLS and port 587 and “require sign in”.
The error is “Unable to open connection to SMTP server”.

On the assumption this would be a reported and known problem, I’ve held off making any changes, or even logging in to the forum.
I’m wondering if other users of this really useful app have seen the same problem.

In the meantime, I may revert to the previous release, which always worked reliably sending and receiving.

It looks like no longer points to an SMTP server. The current server settings can be found here: POP, IMAP, and SMTP settings for

  • SMTP server name:
  • SMTP port: 587
  • SMTP encryption method: STARTTLS

Thanks for the quick reply.
Odd that sending to used to work until immediately before the K-9 5.807 update.
But I’ve changed the outgoing server to and the setting now tests out OK.

Many thanks!

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On doing a bit of Google searching - it seems this was quite a widespread problem, puzzling lots of people, caused by the retiral of the SMTP service.
Coincidentally at the same time as I installed the K-9 5.807 update !

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