MS Account Blocked due to OAuth Emails

OAuth authenticates the mail submission; it does not exempt automated messages from account-protection or sending controls. The few messages you describe do not establish a documented trigger threshold: Microsoft says consumer Outlook limits can vary with account usage history.

While alerts are paused, collect the TrueNAS submission times and SMTP responses, then compare them with the Microsoft account’s Recent activity entries. Review unfamiliar activity carefully and confirm recognised activity only when it is yours. Give Support that correlation rather than repeatedly testing until another block occurs.

The email screenshot also cannot establish authenticity by itself. A displayed sender or a Microsoft-looking link is insufficient; open the account’s Security page independently and check for the corresponding warning. Provide the complete message headers privately to Support if needed. There is no supported guarantee that a particular alert frequency will never trigger protection, and the forum cannot whitelist your application or account.