Mail loop insight

A mail loop is bad because it wastes system resources, consumes your organization's mail volume quota, and sends confusing non-delivery reports (also known as NDRs or bounce messages) to the original senders. This insight reports when a mail loop is found in your organization, the email domains that are involved in the loop, and the number of messages from the previous day that were in the loop.

A mail loop insight in the mail flow dashboard in the Office 365 Security & Compliance Center

You can click View details to see the details in a flyout pane. We also identify the most common loop scenarios and provide the recommended actions (if available) to fix the loop.

Flyout pane after clicking View details in a mal loop insight in the mail flow dashboard