FYI: KC Lemson On Viewing Internet Headers of Mail Messages...

This post by KC Lemson provides some good sample code to view the internet headers of mail messages in Outlook but also illustrates the huge advantage the Outlook 2007 object model provides with the PropertyAccessor object.  Notice the differences between the Outlook 2007 code which is done completely through OOM compared to the Outlook 2003 code which requires the use of CDO 1.21 to access properties on the message.