OUt of the box exchange 2007 or exchange 2010 do not have any great builtin statistical plugins, if you want to get any stats such as how much eamil is sent internally then im afraid its powershell time. Follow the step by step guide below if you would like to see how many emails are sent internally and other stats from your microsoft exchange 2007 or 2010 server.
This is a simple PowerShell Command that creates a text file for your inpection.
1) First drop into powershell and run the following command
Change “domain” to your domain name