Outlook 2007

Open the E-mail you wish to obtain the message headers from in Outlook 2007.
The top left hand corner of the page should have a selection between two tabs; "Message" and "Add-ins". Be sure to have the message tab selected.
Select the "Options" buttion near the top right-hand corner (listed next to Junk E-mail and Find buttons)
The header information will be contained in a box near the bottom of the Message Options page entitled "Internet headers". Copy all of the data in this box for your complete message header information for that message.