You could add Message Options to the Quick Access Toolbar (QAT) and when you have a message selected, click Message Options in the QAT and you can see the ‘Internet Headers’.
I’m not sure if this will show what you want, but give it a try.



To add to the QAT, right click the QAT > Customise the Quick Access Toolbar > Choose commands from > All Commands > Scroll down to ‘Message Options > Add > OK.