Exchange Online Inbox Rule Suppressing Security Notification Emails

Ankit Mehta@Secvyn

•updated Jun 29, 2026•0•0•1

Detects the creation or modification of inbox rules in Exchange/Office 365 that both apply an email suppression action (move to folder, delete, or mark as read) and filter for security-themed keywords (e.g., 'phish', 'MFA', 'SOC'). This behavior is commonly used by adversaries to hide security alerts, multi-factor authentication (MFA) prompts, or phishing incident notifications from a compromised user's mailbox.