Here are some guidelines and resources to help you sort fact from fiction. It wastes time, resources, and bandwidth. The more people you send these to, the worse the damage. These sorts of messages, which tend to be sent repeatedly to large numbers of people, use up computer resources and can clog campus and commercial email servers. If you don't have first-hand knowledge that a story is in fact true, don't pass it along.
Virus hoaxes can be the most damaging.
If you receive a virus warning and you are urged to pass it along, check it out first, and then, if you think it really is something that others should know about, include the URL from an authoritative source, like Symantec or McAfee.