Thunderbird 158.1 receives emails from my new Outlook.com account but cannot send them due to an SMTP OAuth2 authentication failure, despite correct settings and Microsoft permissions.

'''Thunderbird 158.1 – Outlook.com SMTP OAuth2 authentication failure''' I am using Mozilla Thunderbird 158.1 (64-bit) on Windows 11. I recently created a new Outlook.com email account, kim.bailey69@outlook.com, alongside my existing Hotmail and ntlworld.com accounts. The problem Thunderbird successfully receives emails from my new Outlook.com account using IMAP and OAuth2, but cannot send emails from it. The error messages are: "Login to server smtp-mail.outlook.com with username kim.bailey69@outlook.com failed." "Sending of the message failed. Unable to authenticate to Outgoing server (SMTP) smtp-mail.outlook.com." SMTP configuration Server: smtp-mail.outlook.com Port: 587 Connection security: STARTTLS Authentication method: OAuth2 Username: kim.bailey69@outlook.com Troubleshooting already completed Verified all incoming and outgoing server settings. Confirmed IMAP works and messages arrive successfully. Confirmed sending from Outlook.com webmail works. Confirmed my existing Hotmail account sends successfully through Thunderbird. Tried smtp.office365.com as an alternative SMTP server, without success. Created a completely new SMTP server entry and assigned it to the Outlook.com account. The same error occurred. Deleted and recreated Thunderbird's saved Microsoft OAuth2 authentication token. Checked Microsoft's authorised applications page. Thunderbird has explicit permission to send emails, and Microsoft confirms it was used today. Checked Microsoft's recent account activity, which showed no unsuccessful sign-ins. Verified with PowerShell that TCP connections to both SMTP servers on port 587 succeed. Checked that cookies are enabled in Thunderbird. Attempted SMTP diagnostic logging using MOZ_LOG with SMTP and SMTPClient modules, but the resulting log files remained empty. When sending fails, Thunderbird immediately displays the authentication error without opening a new Microsoft sign-in window. My question Why does Thunderbird successfully authenticate to Outlook.com for incoming IMAP mail but fail SMTP OAuth2 authentication, despite Microsoft granting permission to send? Is this a known Thunderbird issue, and what specific diagnostic or corrective action would you recommend that has not already been tried? I would prefer to resolve this without deleting or recreating my existing email accounts, as they contain many years of messages.