The following description is from the CIAC web site:
Chain letters and most hoax messages all have a similar pattern. From the
older printed letters to the newer electronic kind, they all have three
First, there is a hook, to catch your interest and get you to read the
rest of the letter. Hooks used to be "Make Money Fast" or
"Get Rich" or similar statements related to making money for
little or no work. Electronic chain letters also use the "free
money" type of hooks, but have added hooks like "Danger!" and
"Virus Alert" or "A Little Girl Is Dying". These tie
into our fear for the survival of our computers or into our sympathy for
some poor unfortunate person.
When you are hooked, you read on to the threat. Most threats used to warn
you about the terrible things that will happen if you do not maintain the
chain. However, others play on greed or sympathy to get you to pass the
letter on. The threat often contains official or technical sounding language
to get you to believe it is real.
Finally, the request. Some older chain letters ask you to mail a dollar
to the top ten names on the letter and then pass it on. The electronic ones
simply admonish you to "Distribute this letter to as many people as
possible." They never mention clogging the Internet or the fact that
the message is a fake, they only want you to pass it on to others.