Disallowed file types SHALL be determined and enforced.

Why This Matters

Without explicitly blocking dangerous file types (such as executables, scripts, or compressed archives), attackers can easily bypass email security by attaching malicious files that slip through default filtering. Enforcing a disallowed file types policy reduces the risk of malware delivery, ransomware infections, and data breaches originating from email attachments.

What Aether365 Checks

This check verifies that your organization has configured and enforced a policy to block specific file types in Exchange Online email transport rules or anti-malware settings. It appears in the Aether365 dashboard under microsoft-365 checks with severity Medium.