The other day, there was a panic post in a forum about a computer virus that was supposed to destroy your hard disk if you opened an attachment marked invitation. The poster begged us to tell as many people as we could. Now they were passing on the message with the best of intentions, hoping to preserve our computers from a perceived threat, but what they hadn't done was check to see if this was a real or imaginary virus. What I did, which is what I always do now, when I encounter something on the internet that I'm uncertain as to it's veracity, is to check www.snopes.com . This is a website which lists all urban legends, and tells you whether they're true, false, uncertain, partially true, exaggerated, or false but based on a true incident.
When I checked the invitation virus, I found it was a hoax, and I duly informed the forum, thus preventing a cascade of e-mails through cyperspace.
The problem with these cascades, is that when they're posted to an office in an organisation with it's own intranet (I'm thinking of the one I'm familiar with which is the Lothian NHS Intranet), the person in the office then e-mails their contacts, who then e-mail their contacts...and soon the intranet is jammed. This happened most recently with the e-mail about Bill Gates giving $250 to anyone who passes on the e-mail. If you ever get that one, delete it! It's a hoax!
Remember, if it sounds too good to be true, it's a ringer!