How do I view source in Outlook 2010?
Open the email on the Message Ribbon and go to Move > Actions > Other Actions > View Source
It invokes Notepad and shows the full html source.
Double click on the mail, this will open it in a new window.
After that, then click on File > Properties. You will be able to see the header information from there.
For the "view source", right clicking on mails that have a source will by default open it in notepad.
For mails that aren't formatted (in HTML etc), the "view source" option will be greyed out.