It seems Gmail was already caching the images in emails (before today's change to display them by default). Read Mailchimp's post (December 6th): "Image cachi

It seems Gmail was already caching the images in emails (before today's change to display them by default). Read Mailchimp's post (December 6th): "Image caching still lowers our ability to track repeat opens, but turning those images on means we’ll be more accurate when tracking unique opens. At least, theoretically it should work that way" http://blog.mailchimp.com/how-gmails-image-caching-affects-open-tracking http://blog.mailchimp.com/how-gmails-image-caching-affects-o...