While you still are not clear on a couple of issues here, I recieve forwarded emails from people all the time. If you doubt it, run a virus check on it. Did you ask if the person in question forwarded it or re-sent an already forwarded email?
Someone claimed they sent me an important email, but it never arrived (even after days of repeated requests).
They sent me a "forwarded" copy of the email, but I cannot tell if it is a forgery.
Is there any way to unfold whether it is an authentic forward or whether they just mocked it up?