This may also work for different versions of Outlook.
- Open the desired message in a separate window by double clicking on it.
- Once the message has been opened, select File at the upper left.
- Select on Properties
- You may now view the header information in the Internet headers box. I recommend highlighting and copying all the information and pasting it to a notepad document view easier viewing.
- To copy the header: click on the text, select Ctrl+A to select all the text, Ctrl+C to copy the text, open a text document, and then select Ctrl+V to paste the copied text into the text document).