These messages, and messages like it, are almost invariably hoaxes. They generate a lot of unnecessary worry and a great deal of unnecessary email. If not, be skeptical. They usually mean the opposite of what they say. If the message seems geared more to persuade than to inform, be suspicious.
Hoaxers are out to push emotional buttons.
If the message purports to give you extremely important information that you've never heard of before or seen elsewhere in legitimate sources, be suspicious. Read carefully and think critically about what the message says, looking for logical inconsistencies, violations of common sense and obviously false claims. Check for references to outside sources. Hoaxes will not typically name any, nor link to Web sites with corroborating information. Be especially wary of health-related rumors.