As i go through this article, i found StopForwarding.Us may help me. Simply provide your friend’s name and email address, and it will send an email to your friend and ask them to stop forwarding meaningless emails. Your freind will not know who is the person that complain about his/her action and most probably they will though someone is spying on their computer!

Your friend will receive an anonymous email which ask them to stop spamming/forwarding emails and he will recognize his errors in sending those meaningless emails. This is the email that he will receive.
P.S:I personally think that it would be better if let us to include our name or email. So that our friend can only exclude our name in their “mailing list” while let the others interested people still able to read their mails..:)