Glimpse of Nish's world

I know for sure that every one of you have recieved atleast dozen of emails offering some microsoft give-awayas..or an inviations for helping to releasing properties in Nigeria, or some form of chain letters..some times they seems genuine and you wanted to send someone you know, finally causing even your legitimate email also going in to spam folder.
How do you know for sure that an email is a hoax or not..Here is a good site about hoaxes. http://hoaxbusters.ciac.org/