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

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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
    2022-12-29T18:17:29+00:00

    What this guy says! Please Microsoft respond.

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  2. Anonymous
    2022-12-29T16:46:09+00:00

    This is awsome feedback gentlemen! I spent over 8 hours going through various articles and blogs trying different setting changes in Thunderbird and on O365, and nothing worked UNTIL this recommended solution.

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  3. Anonymous
    2022-12-29T15:49:29+00:00

    Yes, this fix worked for me as well. I am using a University account. Seems to be common problem with other users.

    Follow-up: I have helped out about 5 of my fellow professors who had the same problem. A comment from one of my colleagues, "who else but professors (i) are using email on December 26 (revising/submitting marks so that students can register for courses in January) (ii) are using Thunderbird."

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