Office 365 Small Business admins can troubleshoot mail flowproblems by using the Exchange Online message trace tool in the Exchange admincenter. The tool helps admins track specific messages sent in the past sevendays. After you run a message trace, if you can’t diagnose the problemyourself, you can use the detailed information from the tool to post a questionto 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
Set up the 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.
Note Data is retained by the service for seven days.
6. Click Search to run the message trace. To change your search criteria, click Clear.