How to tell which transport rule was applied to an email message?

How to Determine the Transport Rule Applied to an Email Message

Identifying the transport rule that has been applied to a specific email message is crucial for troubleshooting mail flow issues and ensuring proper message handling. Using the Message trace tool in the Exchange Admin Center (EAC) provides an efficient way to pinpoint the responsible rule.

Steps:

1. Locate the Message Trace Tool:

   • Navigate to the Exchange Admin Center (EAC): https://admin.exchange.microsoft.com
   • Click on "Mail flow" in the left-hand navigation pane.
   • Select "Message trace" from the "Tools" menu.

2. Search for the Email Message:

   • Enter the recipient email address or the subject line of the message in the "Search" field.
   • Click "Search."

3. Identify the Applied Rule:

   • In the search results, locate the email message of interest.
   • In the "Details" section, scroll down to the "Message processing history" table.
   • Look for a row with "Applied Rule." This will display the name of the transport rule that was applied.

4. Obtain the Unique GUID:

   • Additionally, the "Applied Rule" row also includes a unique Globally Unique Identifier (GUID). This GUID corresponds to the specific transport rule that processed the message.

Using the GUID:

The GUID can be used to further investigate the transport rule:

• Open the EAC.
• Navigate to "Mail flow" > "Rules."
• In the list of transport rules, locate the rule that matches the GUID.
• Double-click on the rule to view its properties and configuration details.

By following these steps, you can accurately identify the transport rule that has been applied to an email message, enabling you to troubleshoot any issues or make necessary adjustments to the rule's behavior.