Spam help

I have recently been getting spam at my cox email account. It has just started a couple of days ago and it pisses me off because I have been very carefully not to give this account out to anyone. My family and plug only. Now I have heard I can use Kmail to bounce the mail back so they will stop spamming me. Will this work and what else can I or should I do?
TIA
Frank

p.s. in the C.C. block I see that they are only spamming people with cox.net accounts