This is very cool.  Official documentation which helps Universities that use Exchange Labs (Outlook Live) and Exchange on-premises share SMTP namespace. 

 

E.g. If you want students on Outlook Live and fac/staff on Exchange on-prem and want to share SMTP namespace (hickey.edu) this documentation shows you how to accomplish it.

  

Shared Address Space

http://help.outlook.com/en-us/140/cc967280.aspx

 

Configure a Shared Address Space

http://help.outlook.com/en-us/140/dd264651.aspx