In reply to ben b:
Fact: Companies need customers. One way of getting them is to send
unsolicited offers. If people didn't then respond to these offers and
become customers, companies would not send unsolicited offers. Ergo you,
by this method, are probably benefitting from it via increased volumes of
buisiness done by firms that YOU are a customer of!
Returning the unwantred mail in the pre-paid envelopes simply increases a
firm's costs and we all lose.
Best thing to do is simply accept that "junk" mail is a necessary evil
and recycle it.