To begin, open the email message in a new window by double-clicking on it.
On this new window menu, go to View -> Options. If you do not see options, you may have to reveal it by clicking on the two down arrows at the bottom of the menu.
This will have brought up the Message Options window. The last component of this is the Internet Headers. Right-click inside the headers and choose Select All, then right-click again and choose Copy.
Close the Message Options window.
You should now be looking at the original message window. Click on forward and address the message to firstname.lastname@example.org. In the area above the copied part of the message, Paste the Internet Headers and click Send.