I’m not sure why I have trouble remembering this, but I always seem to. I think it’s because very version of outlook has changed how to do this. So, just to remind myself (and everyone else), here are the steps to find the mail headers.
First, DoubleClick the message itself.
Then, go to File/Properties Menu
Click on Properties and at the bottom, you’ll see the headers you are looking for.
Hope this helps!