We use google email log search to trace/view messages sent and received by users. the information found in this area are precious to anyone looking to resolve a mail delivery problem.
How to locate it
1- login to your Google Admin console https://admin.google.com
2- From the Google Admin home page click on Reports
3- then make sure you select Email log Search
4- Fill in the fields or at least the Sender and/or Recipient addresses, then click on SEARCH. The results will be displayed and click on the corresponding Date of the message you are tracing
5- More detail related to the message clicked will be displayed in a new window. the detailed information will show what happened to the message from their you can move on to the next step.
in this case the message BOUNCED and the reason for that is because the server has rejected it with this error Relay access denied