I am using Thunderbird 158.0 (64-bit) on Windows 11 and cannot connect a newly created Outlook.com email account.
The account works correctly through Outlook.com webmail,… (read more)
I am using Thunderbird 158.0 (64-bit) on Windows 11 and cannot connect a newly created Outlook.com email account.
The account works correctly through Outlook.com webmail, but Thunderbird consistently reports:
"Authentication error — Unable to log in at server. Probably wrong configuration, username or password."
I have spent considerable time troubleshooting this problem and have already completed the following checks:
Confirmed that IMAP access is enabled in Outlook.com.
Verified incoming IMAP settings:
Server: outlook.office365.com
Port: 993
Security: SSL/TLS
Authentication: OAuth2
Verified outgoing SMTP settings:
Server: smtp-mail.outlook.com
Port: 587
Security: STARTTLS
Authentication: OAuth2
Confirmed both usernames are my full new Outlook.com email address.
Confirmed that Microsoft lists "Mozilla Thunderbird" as an authorised application, with permission to read, write and send email.
Tested network connectivity using Windows PowerShell. Test-NetConnection outlook.office365.com -Port 993 returned TcpTestSucceeded : True.
Created a completely new Thunderbird profile containing only this Outlook.com account. The same authentication error occurred.
Tested Thunderbird Troubleshoot Mode without success.
Confirmed cookies are enabled and Windows is not using a manually configured proxy.
Removed saved OAuth2 credentials and retried authentication, without success.
Tested both external-browser and internal-browser OAuth2 authentication using mailnews.oauth.useExternalBrowser. Neither worked, and I restored the original value of true.
During an earlier attempt, the Microsoft authentication process displayed the error 127.0.0.1 refused to connect.
Microsoft's authorised applications page confirms Thunderbird has the necessary permissions, but Thunderbird still cannot authenticate. I have not successfully been prompted to enter my new Outlook.com account password through Thunderbird.
My existing Hotmail account works in Thunderbird.
Could this be a known Thunderbird 158 OAuth2 problem affecting newly created Outlook.com accounts?
As the usual configuration, password, permissions and network checks have already been completed, I would appreciate advice on identifying the underlying authentication failure rather than repeating those steps.
Thank you for your assistance.