it wasn’t too obvious to me how to view message headers in outlook 2010 so i did some googling and came across this blog:
http://absoblogginlutely.net/2010/04/view-headers-or-source-in-outlook-2010/

in short, you can customize the ribbon and add the message options button to it to access the header information. also someone pointed out in the comments that you can go to file->properties of a message as well. note: these options only exist when you’ve double-clicked a message to open it.