Fix possible mail loop insight in the Security & Compliance Center
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- Exchange Online Protection
- Microsoft Defender for Office 365 plan 1 and plan 2
- Microsoft 365 Defender
Mail loops are bad because:
- They waste system resources.
- They consume your organization's mail volume quota.
- They send confusing non-delivery reports (also known as NDRs or bounce messages) to the original message senders.
This insight appears only after the condition is detected (if you don't have any mail loops, you won't see the insight).
When you click View details on the widget, a flyout appears with more information:
- Number of messages: You can click View sample messages to see the message trace results for a sample of the messages that were affected by the loop.
- Domain type" For example, Authoritative or Non-authoritative.
- MX record: The host (Mail server) and Priority values of the MX record for the domain.
- Loop reason and How to fix: We'll identify the most common mail loop scenarios and provide recommended actions to fix the loop.
For information about other insights in the Mail flow dashboard, see Mail flow insights in the Security & Compliance Center.
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