In Thunderbird click on View at the top of the page and then click on Headers then All.
The expanded header gives you Received: from unknown (HELO YOUR34EFF17BD0) ([email protected]) by smtp3.knology.net with ESMTPA; 26 Oct 2008 23:49:44 -0000
instead of the original [email protected]
and of course 24.214.112.98 is the IP.
I haven't used Outlook in years but I think it is about the same.