They often appeal to our altruistic side by alluding to people in trouble. Three cents for every person that receives this letter turns out to be a lot of money considering how many people will get this letter and how many people they, in turn, pass it on to. This message contains many of the classic elements of a hoax. These writers know and use the pressure points that misguide us. Because the message seems to be beneficent, recipients tend to be receptive to these pleas.
Children tend to elicit a more sympathetic response.
In this case, the reference to the American Cancer Society adds more credence. The element that differentiates malicious chain letters from other hoaxes is that they target some e-mail address as a central collector of the chain. Unlike postal mail, where you usually are requested to pass the message up or down a specified number of levels, e-mail makes it easy to include a carbon copy to additional parties. In the case of the chain messages, there usually is a reference to a particular address that should be included in any further transmission. This is the target.