Office 365 Small Business admins can troubleshoot mail flow
problems by using the Exchange Online message trace tool in the Exchange admin
center. The tool helps admins track specific messages sent in the past seven
days. After you run a message trace, if you can’t diagnose the problem
yourself, you can use the detailed information from the tool to post a question
to the Office 365 Community or to submit a service request.

 

Run a message trace

The message trace tool is located in the Exchange admin center
(EAC), which is connected to the Office 365 portal.

 

Access the EAC

  1. In the Office 365 portal, at the top of the page, select Admin and choose Exchange.

 

 

 

 

 

  1. In Outlook Web App, go to the address bar in your browser and replace the URL to the right of https://outlook.office365.com/ with ECP.
  2. For example, if your Outlook Web App URL is https://podxxx.outlook.com/owa/..., change it to https://podxxx.outlook.com/ECP, and hit ENTER. That will take you to the Exchange admin center.
  3. Bookmark the EAC in your browser for future access.

 

Set up the message trace

  1. In the EAC, go to Mail flow > Message trace.

 

 

 

5. Fill out the following fields, as needed. None of these fields is required. If you click Search without entering anything, you’ll get all message trace data for the default time period, which is the last 48 hours.

 

  • Sender   Narrow the search to specific senders by adding users to the Sender field.
  • Click Add users, select one or more senders from your organization, and then click Add. To add external users who aren’t on the list, in the Check names box, type their email addresses and click Check names. When you are done, click OK.
  • Recipient   Narrow the search to specific recipients by adding users to the Recipient field.
  • Click Add users, select one or more recipients from your organization, and then click Add. To add external users who aren’t on the list, in the Check names box, type their email addresses and click Check names. When you are done, click OK.
  • Message was sent or received   Select the time interval during which a message was sent or received. Choose among:
  • Last 24 hours
  • Last 48 hours   This is the default value.
  • Last 7 days   For messages sent or received within the last seven days, starting at 12:00 A.M. on the day you run the message trace.
  • Custom   Select the time zone and the time interval you want.

 

 Note    Data is retained by the service for seven days.

 

  • Delivery status   You can search by the specific status of a message or messages. Leave this field blank to cover all statuses. Otherwise, choose among:
  • Delivered   The message or messages were successfully delivered to the intended destination.
  • Failed   The message or messages weren’t delivered. Either delivery was attempted and failed, or delivery was prevented by the filtering service. For example, the filtering service may have determined that a message contained malware.
  • Pending   Delivery of the message or messages is still being attempted or re-attempted.
  • Expanded   The message or messages were sent to a distribution group and was expanded so the members of the group can be viewed individually.
  • Unknown   Delivery status is unknown and no details are available.
  • Message ID   The Internet message ID (also known as the client ID) found in the header of the message with the Message-ID: token. Its format varies depending on the sending mail system. The following is an example: <08f1e0f6806a47b4ac103961109ae6ef@server.domain>. If you know the message ID, it may help in troubleshooting.

 

6. Click Search to run the message trace. To change your search criteria, click Clear.