M365 Direct Send internal spoof — From-domain == To-domain + Outlook relay + SPF/DKIM/DMARC fail (Varonis 2025)
m365-direct-send-internal-spoof
What this tier means
High-confidence threat indicator — phishing, impersonation, BEC, or scam pattern. Strong contributor to the trash decision.
How Gorganizer detects this
Email appears to come from inside the recipient's own tenant (From-domain matches recipient domain OR sender address literally equals recipient address) and was routed via tenantname.mail.protection.outlook.com, but Authentication-Results shows SPF/DKIM/DMARC fail. Attackers abuse Microsoft 365 Direct Send smart-host to deliver spoofed-internal phishing that bypasses most anti-impersonation logic because the email is technically relayed through a "trusted" Microsoft endpoint. Varonis documented an active campaign impacting 70+ organizations since May 2025 (PowerShell-delivered PDF+QR credential phishing).
False-positive guard
Every signal in Gorganizer feeds a multi-module score — never a sole verdict. This is a threat-tier signal — it adds a strong contribution to the trash score. The full pipeline still requires convergence across multiple modules + a margin over the safety floor before deletion happens, and Gmail's trash (30-day recovery) is always used — never permanent delete.
About the scoring engine
Gorganizer's scoring engine emits 2,143+ signals across six modules — headers, sender, subject, body, attachments, and structural metadata. Every email is scored by every module independently; the final verdict requires multiple modules to agree and the trash score to beat the safety floor by a margin.
Sacred safety guards — never delete starred emails, replies, calendar invites, receipts/invoices, or attachments — apply unconditionally regardless of any signal.
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