So I have been going around in circles for the last 20 minutes trying to edit the default email address policy in exchange 2010 and when I use the EMC to do that it fails with some "Conditional Attributes" message!! such a pain.. so anyhow I think I might have found out how to edit the dam policy but its through the EMS not EMC and the command I run is
get-emailaddresspolicy default* | set-emailaddresspolicy -enabledemailaddresstemplates SMTP:%email@example.com,smtp:%firstname.lastname@example.org
Update-emailaddresspolicy -Identity default*
Hope this helps and let me know if you manage to find alternate ways to achieve this shit!