Exchange Server 2013 delivery reports is a message tracking tool that allows you to search for emails that were sent and receive by users in and outside of your organization.
Exchange Server 2013 simplified the process of searching and allows you to track messages for up to 14 days after they were sent and received.
To access the Delivery Reports open EAC -> Mail Flow -> Delivery Report
Fill in the details of the search and click on Search
Note that delivery report only track messages sent by Outlook or Outlook web app, email sent via POP and IMAP clients are not tracked.