Thunderbird IMAP responded: User is authenticated but not connected

Question

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

Answer 1

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

Answer 2

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!

Answer 3

Hello Juan, happy to help you today dear :)

This error means that the authentication process for your account was succesfull, but for some reason the mail server is not giving Client access to the account data, so it cannot synchronize your messages into the app.

it needs to be resolved from the side of the mail server that actually contains all your data. Reach out to your admin in your organization or provider of the email account so they can fix the issue.

If this is happening with an email account that is set up using an Alias and not the Primary email address, try setting up the account anew using the primary email address to see if that resolves the problem.

Hope this helps! have a great day

Alyssa

Answer 4

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..).

Answer 5

I confirm SMTP with OAuth2 works but not IMAP with OAuth2