Thunderbird IMAP responded: User is authenticated but not connected

Anonymous
2022-12-27T12:29:12+00:00

Since yesterday, my Thunderbird client cannot connect to the outlook.office365.com IMAP server and other users at my university are also having this problem. I have deleted the stored token and redone the connection procedure but it does not work. I get two error messages:

The current operation on 'inbox' did not succeed. The mail server for account ... (IMAP) responded: User is authenticated but not connected.

Server outlook.office365.com has disconnected. The server may have gone down or there may be a network problem.

This does not work on any platform: Windows, Linux or Macos. Via the browser, we can access the emails but it is a workaround because it does not support openPGP. We need Thunderbird

Outlook | Web | Outlook.com | Account management, security, and privacy

Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

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Anonymous
2022-12-28T22:03:29+00:00

Hi Glenn,

Which version of Thunderbird are you using.

I have 102.6.1 which is the latest one. Can you try updating it if its not and then check.

Also under Thunderbird --> Click on the gear icon on the bottom left bar --> General --> Config Editor --> Show All

Type network.dns.dis in the search field

Select the very first option and click on the toggle arrow on the right, make it true

Close and reopen Thunderbird.. See if this helps

Let me know how it goes

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Anonymous
2022-12-28T21:34:14+00:00

Yes, it is worked for me too!

I just disabled ipv6 netwotking in thunderbird advanced configuration editor (network.dns.disableIPv6 = true)

and it is works again like a charm!

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  1. Anonymous
    2023-01-30T14:21:20+00:00

    Hello TAN,

    It is unlikely that you are seeing this issue because of the bug that Microsoft had in their IPv6 endpoint because they already fixed that and the problem has not recurred for us. There are other errors which show up with this same message. You can see some possibilities here: https://stackoverflow.com/a/55190289 . Particularly note that it is common to see this when formatting credentials incorrectly when attempting to access a shared mailbox.

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  2. Anonymous
    2023-02-22T09:13:49+00:00

    I'm having the same issue today and disabling IPv6 didn't work.

    Outlook.com is having issues with third-party apps on and off for the last few months now.

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  3. Anonymous
    2023-04-03T01:54:30+00:00

    Check this detailed article on Thunderbird IMAP responded: User is authenticated but not connectedwhich explains reasons, fixes & all possible workaround in detail

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