Ever since they announced caching of all images, I am starting to notice that almost every email I receive in my Gmail account has broken images.<p>Getting out of the email and back in seems to be solve the problem most of the time.<p>I fired up Firebug and noticed that Google's proxy server is returning a 404 on the images the first time the email is loaded but, after a few more calls to the same URL, the image is returned.<p>Does anyone know the cause? And if there is a fix? We send out a monthly newsletter and getting lots of reports from our users about not being able to see images.