In an email with 5 images only one of them is replaced by a box with a small icon of a page in the center instead of an image and I cannot figure out why this image is being blocked/not appearing. When I right-click on the image and select "Inspect Element" I get Adblock Plus references that say "Failed to load resource: the server responded with a status of 404 (Not Found)" and "Failed to load resource: the server responded with a status of 403 (Forbidden)". Is it possible that the image is no longer available from the sender of the email? Thanks for any help you may offer.
Sound like the actual image was not in the email, but a link to the image was. When you tried to retrieve the image, the server it di not respond.