Good rule of thumb:
If it's funny, pass it on.
If it's not and it tells you to pass it on, then just don't
I've got a friend who sends me stuff to check if it's real or not, which I don't mind as it saves any hoaxes/spam being sent on.
But someone else I told had sent me a hoax about a baby suffering from cancer and emails were being tracked to fund a cure (and I gave links to pages showing it as a hoax) turned round and said I was lying and it was true and very beautiful.
I don't get email from them anymore which isn't a great loss
Anyway, must dash to pick up my lovely gf