In previous versions of Microsoft Outlook (the classic app), you could view the HTML code of an email by opening the email, right-clicking on it, and selecting “View source” from the context menu.

In Chrome, go to chrome://extensions/, enable Developer mode using the toggle in the top-right, then click the “Load unpacked ...

It's been a while since I've dealt with strictly client side web stuff-- How in the name of all that is holy do I just include another HTML file (containing only a ...