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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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  1. 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

    312 people found this answer helpful.
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  1. 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!

    131 people found this answer helpful.
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  1. Anonymous
    2022-12-28T16:56:31+00:00

    Thanks for the answer. We do not use Basic Authentication, we use OAuth2. The problem has start during vacations so I do not think any admin made any change in the configuration. To be sure I send a question and I'm waiting for reply.

    4 people found this answer helpful.
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  2. Anonymous
    2022-12-28T20:09:07+00:00

    I have same problem with Windows 10 workstation using Thunderbird and try to load IMAP messages (oauth2). POP3 does not work at all, cannot even login. SMTP works fine. Same account works on Mac thunderbird fine. Web Outlook works also fine.

    1 person found this answer helpful.
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  3. Anonymous
    2022-12-28T19:07:33+00:00

    No Basic used here. NTLM, Oauth2, etc.. are being used and stopped working 2 days ago.

    1 person found this answer helpful.
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