optimal? first reply has it and subsequent don't. that sounds more optimal.
Ideally, only the first person to send an email should have a graphic in their signature, if at all. Anyone replying to an email, whether the first or 92nd time, should not.
It comes down to how many of the anti-spam systems work. In addition to obtaining RBL and similar scores, the content is scanned for things like multiple URLs or graphics, as well as the size (dimensions and byte-count) of the images. These generally add low weights to the spam score, but enough of them can push it over the edge and prevent delivery.
Glenn
_________________________
Actually I
am a Rocket Scientist!
