I confirm that to solve this problem you have to change the Thunderbird setting network.dns.disableIPv6 from false to true.

To do this proceed as follows:* - Open Tools / Settings - In the Settings tab go to the bottom right corner on the Configuration Editor - Show all - Search for setting network.dns.disableIPv6 - Change the value which should be false to true

THANK YOU, THANK YOU, THANK YOU - I've been struggling since Dec 27 - which is apparently when you started having the problem. I tried lots and lots of different settings for ports and authorization to no avail in Thunderbird. It didn't seem to matter what the settings were in my Microsoft Outlook account, everything worked when sending an email from Thunderbird to the Outlook account. I could send from Thunderbird, but not receive anything. Also none of the folders attached to the Thunderbird account worked.

Your post solved the issue immediately.

Interestingly IPv4 and IPv6 on my computer were already disabled in WiFi and Local Connection but changing to True where you indicated did the trick.

THANKS again!!!

Seems whatever was causing this at Microsoft has resolved itself, at least for me. So if you want to use IPV6 again for you e-mails, try re-enabling it. Hypothetically IPV6 should give you better performance but it's not likely to be noticeable with just e-mails.

After some unproductive back and forth with a Microsoft technician who was adamant it couldn't be a MS issue, they now seem to at least entertain the possibility that it could be and are asking if I can generate some kind of debugging report in Thunderbird that I can send to them. Is it possible to somehow generate a report that shows Thunderbird connecting and failing to fetch the mailbox that I could forward to them? I doubt much will be done since the IPV4 workaround is working for most folks, but we can but try.

Logging tends to hide user names and passwords, but logging is about the best way forward I would guess. https://wiki.mozilla.org/MailNews:Logging I would guess an IMAP log would show the failure. Although you might find something useful in the error console (ctrl+Shift+J) as well.

Hi all,

As I mentioned earlier this this thread, I opened a support case with Microsoft Office 365.

They wrote to me on January 11 saying the problem should be resolved and asked me to re-test.

I confirm I was able to set the network.dns.disableIPv6 setting back to the default false value and Thunderbird can once again authenticate fine using OAuth over the IPv6 protocol path.

Regards, Tim

Disabling IPv6 is NOT THE FIX for this issue. I use TB with multiple GMAIL, EXCHANGE and ZOHO accounts. On all of them, including one of the exchange accounts, IMAP works fine. The other exchange account shows the error. This same account works fine in TB with POP access. It also works fine with via outlook 365 web and Windows Mail (Win 10). So, I suspect that this may have to do with the account's setup on the server side.

BTW, I did try the "disable IPv6" fix and it did not help.

EDIT: Inquired with the Exchange account's admin and received a response: THE ACCOUNT IN QUESTION HAS IMAP ACCESS DISABLED. Thus, first step should be to determine if IMAP access is enabled on the account.

I am currently experiencing the same issue as @dreyder - disabling IPV6 did not address the issue.

==================================

An installation on Windows (corporate company computer) and on Linux (personal laptop) result in the same error messages:

   "The current command did not succeed. The mail server for account owen@company.com responded: User is authenticated but not connected."

then

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

Also tried to get a POP connection working but no luck there. The SMTP connection is working fine.

==============================================

I then tried using the Microsoft testconnectivity site: https://testconnectivity.microsoft.com/result/3cc56670-d6f4-c06c-fa6c-ddeccb6e5ccd This yielded the following output: Testing IMAP for user owen@corporate.email.com on host outlook.office365.com:993:SSL. The IMAP test failed. Test Steps Attempting to resolve the host name outlook.office365.com in DNS. The host name resolved successfully. Additional Details Testing TCP port 993 on host outlook.office365.com to ensure it's listening and open. The port was opened successfully. Testing the SSL certificate to make sure it's valid. The certificate passed all validation requirements. Test Steps The IMAP service is being tested. There was an error testing the IMAP service Additional Details Protocol Log: C: 1 CAPABILITY S: * OK The Microsoft Exchange IMAP4 service is ready. [RABNADUAUABSADAANwBDAEEAMAAwADYAOAAuAG4AYQBtAHAAcgBkADAANwAuAHAAcgBvAGQALgBvAHUAdABsAG8AbwBrAC4AYwBvAG0A] S: * CAPABILITY IMAP4 IMAP4rev1 AUTH=PLAIN AUTH=XOAUTH2 SASL-IR UIDPLUS MOVE ID UNSELECT CHILDREN IDLE NAMESPACE LITERAL+ S: 1 OK CAPABILITY completed. C: 2 AUTHENTICATE XOAUTH2 ******** S: 2 OK AUTHENTICATE completed. C: 3 LIST "" * S: 3 BAD User is authenticated but not connected. Exception details: Message: The IMAP server responded with an error status "3 BAD User is authenticated but not connected.". Type: Microsoft.M365.RCA.Services.Protocols.Imap.ImapServerErrorException Stack trace:

  at Microsoft.M365.RCA.Services.Protocols.Imap.ImapCommand`1.CheckForOk(IList`1 response)
  at Microsoft.M365.RCA.Services.Protocols.Imap.ListCommand.ProcessResponse(IList`1 response)
  at Microsoft.M365.RCA.Services.Protocols.ProtocolClient.<SendCommandAsync>d__17`1.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
  at Microsoft.M365.RCA.ConnectivityTests.ImapPop.BaseProtocolTest.<PerformTestInternalAsync>d__12.MoveNext()

==============================

I was able to login to various other clients though (eM, Mail, Outlook). These all seemed to correctly intuit the settings with just my corporate email (unlike Thunderbird) and connected + downloaded through IMAP fine. Does this perhaps indicate that Thunderbird is sending wrong requests after authentication? (After scouring their GUIs thoroughly I was not able to find their IMAP settings to check alignment of server/security inputs. etc.)

The original cause of this issue was a problem with IPv6 at the MS end, I had a support request in with MS and they confirmed to me that this was the case when the issue was fixed. I suspect the error message is fairly generic and can be triggered by a range of issues, which is probably why the "disable IPv6" fix is no longer working. I'd recommend that anybody who is seeing this error and can't find an account set up issue, puts a support request in to MS, that seemed to do the trick the last time around.