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
    2022-12-30T09:33:58+00:00

    Just had contact with Microsoft and it seems they are now aware that this is a major issue.

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  2. Anonymous
    2022-12-29T18:11:11+00:00

    Yes, this is precisely why this issue is in Microsoft’s court and requires Microsoft to take action. Users should not need to be aware of IPv6 and IPv4. Putting out a broken service on IPv6 is more harmful to the efforts to transition away from IPv4 than keeping a service IPv4-only.

    You do have one option: you can create multiple profiles in Thunderbird. It is annoying and prevents you from copying between folders which are on servers with different IPv6 requirements.

    You also have another option (which I have not tried). You might be able to add an IPv4-only entry to your hosts file for outlook.office365.com. This should prevent Thunderbird from trying to access the IPv6 endpoint. You will need to remember to remove this once Microsoft fixes this issue or to update it whenever Microsoft updates their DNS records. In a similar vein, if you control your local network infrastructure, you might be able to use something like dnsmasq to do this for all your local devices. It might even have an option to proxy DNS results but filter out IPv6 results for specific hosts (I mean, such an option would be useful here and this is the sort of thing I expect that tool to provide, though maybe it is global only, etc., but I have not checked its documentation).

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  3. Anonymous
    2022-12-27T15:07:32+00:00

    Our clients are seeing the same behavior. It was working fine and they can send over SMTP but logging in simply says "authenticated" but no new emails show in the inbox. Webmail works fine but thunderbird isn't working correctly regardless of authentication method (Oauth, NTLM, Etc..).

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