I’ve made an update to the popular “Exchange Proxy Address (EmailAddresses) Report” script. If you’re into in that sort of thing, check it out:
https://mikecrowley.wordpress.com/2012/04/16/exchange-proxy-address-alias-report
Sample output to screen
Sample output shown in Excel
Mike Crowley's Whiteboard 
Here is a similar script for the GrantSendOnBehalfTo attribute: http://social.technet.microsoft.com/Forums/exchange/en-US/740000fb-710d-4db1-9207-d265c5bfd07e