Non-accepted domain report in the Security & Compliance Center

Important

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The Non-accepted domain report in the Mail flow dashboard in the Security & Compliance Center displays information about messages from your on-premises email organization where the sender's domain isn't configured as an accepted domain in your Microsoft 365 organization.

Microsoft 365 might throttle these messages if we have data to prove that the intent of these messages is malicious. Therefore, it's important for you to understand what's happening and to fix the issue.

Non-accepted domain widget in the Mail flow dashboard in the Security & Compliance Center

Report view for the Non-accepted domain report

Clicking the chart on the Non-accepted domain widget will take you to the Non-accepted domain report.

By default, the activity for all affected connectors is shown. If you click Show data for, you can select a specific connector from the dropdown.

If you hover over a data point (day) in the chart, you'll see the total number of messages for the connector.

Report view in the Non-accepted domain report

Details table view for the Non-accepted domain report

If you click View details table in a report view, the following information is shown:

  • Date
  • Inbound connector name
  • Sender domain
  • Message count
  • Sample messages: The message IDs of a sample of affected messages.

If you click Filters in a details table view, you can specify a date range with Start date and End date.

To email the report for a specific date range to one or more recipients, click Request download.

When you select a row in the table, a flyout appears with the following information:

  • Date
  • Inbound connector name
  • Sender domain
  • Message count
  • Sample messages: You can click View sample messages to see the message trace results for a sample of the affected messages.

Details flyout after selecting a row in Details table view in the Non-accepted domain report

To go back to the reports view, click View report.

For information about other insights in the Mail flow dashboard, see Mail flow insights in the Security & Compliance Center.