Adding outlook.de account fails with "User is authenticated but not connected"

[VanniViolett]

Checklist

• I have used the search function to see if someone else has already submitted the same bug report.
• I will describe the problem with as much detail as possible.

App

Thunderbird for Android

App version

v11.0 + v12.0 b7

Where did you get the app from?

Other

Android version

13 Stock rom

Device model

Samsung Galaxy S20FE

Steps to reproduce

1. Add New account
2. Entering Email adress "...@outlook.de"
3. Manual entering IMAP Server config for outlook.office365.com with OAuth 2.0
4. Accept authofication for Firebird over Microsoft Authentificater
5. Accept that a new App added to Outlook Account via Microsoft Authentificator
6. Firebird shows a Server error "User is authenticated but not connected"

Expected behavior

Adding authentificated Email account

Actual behavior

can't adding authentificated account because of a failure the Server sends

Logs

Enabled logging

k9mail-logs.txt

[krzysdz]

This is a known problem with Outlook when connecting over IPv6.

https://learn.microsoft.com/en-us/answers/questions/4586042/thunderbird-imap-responded-user-is-authenticated-b?forum=outlook_com-all&referrer=answers
https://support.mozilla.org/en-US/questions/1400644

[throwaway242685]

i'm having the same problem, what do I do?

[Kartatz]

same

[tcecyk]

(to link threads, came up here first: #7270)

the open question is if k9mail can fail more gracefully and fallback to / retry on ipv4

[dnet890]

it is not just outlook de. But, outlook.com is affected too

[sBERSAN]

Why it is not yet fixed? I have same problem.

[siffegh]

The solution to that problem is usually this:

• go to https://www.outlook.com > sign in to your email account

• go to Settings > Forwarding and IMAP > enable 'Let Devices & Apps use IMAP'

But it didn't work here.

[deminimis]

Same problem still here, I tried on both Thunderbird for Android and Windows, both manual and auto-settings.

Edit: there was a sign-in button on Outlook for forwarding before it would show a toggle for allowing IMAP or POP. After signing in from the settings and then toggling that on, it worked.

[rafaeltonholo]

Hi everyone,

This is a common Outlook issue caused by the POP3/IMAP forwarding not being enabled. Please read and follow all the instructions in Microsoft's documentation: Microsoft's documentation

As mentioned by @deminimis, sometimes Microsoft requests you to re-authenticate before enabling this setting. If you don't, the change won't be applied.

I will close this issue since it isn't on our end.

Thanks for understanding.

[rafaeltonholo]

Please note that Outlook is not saving the "POP and IMAP" changes, even after signing in again. I recently created a new account, and when attempting to enable IMAP usage and clicking "Save," the user interface indicates that the setting has been applied. However, upon refreshing the mail, the setting reverts to its previous state.

Screen capture of the issue:

Screen.Recording.2026-06-29.at.10.06.31.AM.mp4

If you are experiencing the same problem, I recommend reporting it to Microsoft so they can be made aware and work on a fix.