Outlook.com account fails with "User is authenticated but not connected" while another Outlook.com account works
Thunderbird version: 153.3.1 ESR Operating system: Windows
I have two free Outlook.com accounts configured in Thunderbird.
One Outlook.com account works normally. The other Outlook.com account consistently fails.
Error message:
"User is authenticated but not connected."
What I have verified:
- OAuth2 is configured for IMAP and SMTP. - IMAP is enabled in Outlook Web settings. - Web Outlook works normally. - Outlook for Windows works normally. - Spark Mail on iPhone works normally. - Another Outlook.com account works in the same Thunderbird installation. - Betterbird shows exactly the same behavior. - The account has been recreated multiple times. - Saved passwords and OAuth tokens have been deleted. - A new Thunderbird profile was tested. - The browser used for OAuth authentication was changed and tested. - OAuth authentication completes successfully in the browser. - IPv6 was disabled (network.dns.disableIPv6=true), but the issue remained. - The failing account uses the primary Outlook.com alias, and the username matches the primary alias. - hostname, authMethod, and type settings are identical to the working Outlook.com account.
Relevant log output:
D/IMAP XOAUTH2 auth
15 NO User is authenticated but not connected.
Additional observation:
OAuth authentication succeeds, and Thunderbird proceeds to XOAUTH2 authentication. The Microsoft server then replies:
"NO User is authenticated but not connected."
Has anyone seen this behavior with a specific Outlook.com account while another Outlook.com account works correctly in the same Thunderbird installation?
All Replies (1)
Thunderbird version: 153.3.1 ESR Operating system: Windows
I have two free Outlook.com accounts configured in Thunderbird.
One Outlook.com account works normally. The other Outlook.com account consistently fails.
Error:
"User is authenticated but not connected."
What works:
- Outlook Web - Outlook for Windows - Spark Mail on iPhone - Another Outlook.com account in the same Thunderbird installation
What fails:
- Thunderbird 153.3.1 ESR - Betterbird (latest version)
What I have verified:
- OAuth2 is configured for both IMAP and SMTP. - IMAP is enabled in Outlook Web settings. - OAuth authentication completes successfully in the browser. - The account has been recreated multiple times. - Saved passwords and OAuth tokens have been deleted. - A new Thunderbird profile was tested. - Different browsers were tested for OAuth authentication. - IPv6 was disabled (network.dns.disableIPv6=true), but the problem remained. - The failing account uses the primary Outlook.com alias, and the Thunderbird username matches the primary alias. - The account has multiple aliases, but Thunderbird is configured with the primary alias. - hostname, authMethod, and type settings are identical to those of the working Outlook.com account. - POP with OAuth2 was also tested and failed with the same behavior.
Relevant log output:
D/IMAP XOAUTH2 auth
15 NO User is authenticated but not connected.
Additional observations:
- OAuth authentication succeeds. - Thunderbird proceeds to XOAUTH2 authentication. - The Microsoft server then replies:
"NO User is authenticated but not connected."
- The same account works in Outlook Web, Outlook for Windows, and Spark Mail on iPhone. - The same Thunderbird installation can access another Outlook.com account without any issues. - The same problem occurs in Betterbird.
Based on the log, it appears that authentication succeeds, but the Microsoft server refuses to connect the mailbox afterward.
Has anyone seen this behavior with a specific Outlook.com account?
Could this be related to a Thunderbird/Microsoft OAuth interoperability issue rather than an account configuration problem?
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