A message from John Doe invites me to obtain lots and lots of cash, (numbers with many zeros given) by joining a chain. However, to benefit from this money chain I must have a PayPal account, the details of which will have to be divulged etc. etc. etc.
Dear John Doe,
Sorry I cannot answer in any further detail just now. I am having a vigorous communication with a Prince in a certain African state. However, you should be aware that your mail has been reported as the scam that it is, and sent the way of all scams.
May your troubles multiply.