If you got the Email through an ISP, then you can forard it with full headers to the abuse line, as in abuse@MyIsp.net
Some ISPs ignore them, and mine tries to take action on every one.
They can sometimes get in touch with the real sender's ISP and as them to warn the user that they have been had.
step one is ask your ISP. If you are your own ISP, well, smile...
As you probably know, the Form: is likely not from whom it came.