Oulook calendar invites issue in Mac Mail

[gryphon]

Hi,
I have someone who uses Outlook 2010. When he sends meeting invites, I get an .ics attachment but not the email message.

He goes to his calendar, creates an entry and adds me as an invitee. He types a message and sends. I get an email from him with nothing but an .ics attachment. If I double click the attachment, it adds to my iCal and then I can double click the event on my calendar and see the email message in the notes.

Why won't his email message appear in body of the email he sends me?
It works as expected when he sends to another Outlook user.

I'm on Mountain Lion if that could make a difference, but I figure it's something in settings on his end?

I've tried hacking registry to set his Outlook back to OL2007 method of including the Where and When in the body of the email. But I still get no message on my mac (works to a Windows Outlook user).

I've tried with his Outlook option checked AND unchecked in Calendar options to send .ics files.

I'm stumped and would appreciate any help.

thanks!