This only works for inline images because Google caches them, and then you get the images from Google’s cache. It has nothing to do with external links. If Goo

This only works for inline images because Google caches them, and then you get the images from Google’s cache. It has nothing to do with external links. If Google redirects you to a website, you’re still going to the website. Unless Google internally follows all the links in emails it won’t do anything to help spam. Not to mention all tracked links I’ve ever seen track primarily based on the URL itself. Additionally, Google adding a redirection step won’t save anything, except show via HTTP Referer that you were linked to this page by Google. If you clicked the link from a desktop IMAP client you’d have no referer, so this is a net loss for privacy, not a gain.