EPA is great tool to understand the current users profile and it’s fairly simple to run this tool and generate the result.

This tool cannot be used for Exchange 2010 as it uses WebDev to pull the data and Exchange 2010 does not support WebDev

Here is the PowerShell script from Rob Campbell which can get the similar stats from exchange 2010 servers as well. This will scan through all the transport servers’ logs from the previous day, and generate stats for each user, by primary smtp address, for

Total Messages and Bytes Sent
Unique Messages and Bytes Sent
Total Messages and Bytes Received
for both Internal and External emails.

http://gallery.technet.microsoft.com/scriptcenter/bb94b422-eb9e-4c53-a454-f7da6ddfb5d6#content