Without knowing more details about your inbound/outbound email router configuration, I could point you to some literature for setting up the email router for:
Exchange 2010
Exchange Online
Important
things to know about configuration, and
troubleshooting the email router.
What happens when you open the email in question (outside of UR7 read only forms optimization) - do you see a yellow info bar at the top of the email?
I hope this helps. If my response answered your question, please mark the response as an answer and also vote as helpful. Michael Mayo