Is this honestly the first email forwarded to you that was factually incorrect? It is part of the mixed blessing of instantaneous communication. Everyone, including those who do not take the time to check the validity of the information, has a "forward" button, and an address list. IMO, email would be far better without those two little innovations.
The majority of these things get sent around so much that they show up on the radar of a site like
www.snopes.com . The best method to dealing with an email like this is to delete it, and let the person who sent it know that you do not need to receive such emails in the future. If you are one of those people who simply cannot keep your pointer off the "forward" button, at least check the validity before you forward.