I agree it’s a good habit to write a short summary before a long email essay. However, it’s easy to do this by hand, so what would be the specific benefit of this Gmail lab feature? Commenter Mike, you say you would use this lab, what’s your motivation for that?
More often than not, I’ll delete an email if it is one gigantic block of text, even if it is on an interesting topic. Big chunks of content work for some industries, but make sure you mix up the content types (video links, images, charts) and calls to action (buttons, graphics) in your emails to keep it interesting and give your audience’s eyes a break. No one likes an “email essay.”
Email Essay Review - SCC Writing Center