I understand taking footprints of images is not that easy. Spammers are now breaking up a single image and attaching several smaller images - that make up the lager image that the end user eventually sees/reads.

To an end user two emails look identical - but they're not! The image in one email will be made up of, say, 4 smaller images and the image in another email will be made up of, say 6 smaller images.

Spammers are also changing the sizes of how these images are broken up.

[I dunno if I'm explaining this very well] Basically, what I'm getting at is each email will be pretty much unique making footprint detection extremely difficult.

Lee