Microsoft, Disney and the GAP are not giving away stuff for free. There is no way for anyone to count the number of copies of an email in circulation on the internet, nor to count the number of times something has been forwarded. Email systems are like blind, deaf mute postal workers, who process mail my feel. Furthermore, they are all forbidden to try and communicate with each other, and even if they didn't, they all dislike each other anyway. Tracking a message through such a system would be practically impossible.