How to switch between Dark and Light Mode specifically for emails in Mail on macOS Mojave

Apple’s Mail app in macOS Mojave brings its own Dark Mode that can be set separately of the rest of the system. While Mail’s Dark Mode makes reading text-only emails difficult, the good news is that you can set your Mac to Dark Mode, but leave Mail in Light Mode for maximum legibility. In this step-by-step tutorial, you’re going to learn how to alternate your Mail app between Light and Dark mode at will.