Returning E-mail On An Addon Domain [moved]

Returning E-mail On An Addon Domain

I registered a recently expired domain name and added it to my site as an addon domain. One problem is I'm getting a lot of spam from that domain and I have no reason to use it at all. So how can I tell cPanel that every time I receive an e-mail for that domain to trash it or hopefully trash it and send something back to whoever sent it to the first place saying the e-mail address is not valid?