[calvinmorrison]

By the time you check if the image is 1x1, you've already downloaded it.

The alternative expensive solution is to download EVERY image a user receives and store it indefinitely. That way the trackers aren't any more useful than "was the email received".

In short, I'd love a better solution to " load all images " vs " load no images " but that's where I ended up talking to our frontend engineer at Fastmail. Obviously he had thought about the problem a lot more then me (I do operations not any frontend) and there's no easy solution.