Revenge on the Direct Junkmail Companies

A lot of people complain about getting SPAM in their email inbox. Yes, it's a hassle, it wastes CPU cycles and as a result, electricity... but there's not a whole lot that can be done other than blacklisting and lawsuits. A few major ISP companies are promoting a system of micropayments: How this would work is for every email over 10,000 that you send in a week-- you have to pay 1/100 of a cent to your ISP, email provider, etc. For most of us-- we'd never have to pay a cent. For major spammers that send out tens of millions of emails daily... this adds up fast.
Sounds like a brilliant and novel idea: Make SPAM not financially worthwhile to the SPAMmer. But how would this system translate to traditional paper-junkmail? Paper junkmail is in many ways worse because of the physical environmental costs of producing the paper, printing, running the machines to design and distribute, etc. So how do you combat direct-junkmail? Mail them a brick... at their expense.