How is spam getting into you list?  Are you using appropriate anit-spam
controls?  Do you have policy (WELCOME file) with "teeth?"

The lists that I cooperate have:

* SUBSCRIPTION= OPEN,CONFIRM

and

* SEND= PRIVATE or * SEND= EDITOR and EDITOR= my_RFC822_addr,(listname)

This goes a l_o_n_g way in my spam_diet.  Customers are happy,
administration is happy, therefore, I'm happy (and I don't have to edit
archives either).

/Pete