When trying to enumerate your Exchange Organization you may receive an error message "Unable to connect to an Exchange Server"
The "Run-As" account within the task properties dialog is actually what is used for connecting to an Exchange server. To be able to connect to an Exchange server, the "Run-As" account within the Task properties dialog must have administrative privileges on the Exchange Server you are trying to connect to. To verify this, right-click on the Tasks node in the MessageStats console and click on "Properties". One of the tabs is titled "Task Credentials". This is where the administrative user should be entered.