Junk email distributors are much more vulnerable at the receiving end than at the sending end, research finds.
A given spam campaign may use thousands of mail relay agents to deliver its millions of messages, but it may use only a single server to handle requests from recipients who respond. A single takedown of a scam server -- or a spammer redirect -- can curtail the earning potential of an entire spam campaign...
http://www.darkreading.com/document.asp?doc_id=131093&WT.svl=news1_2
Urs
Sadly, if a spammer doesn't make money from his spam, all that generally happens is that he increases his spread. If he didn't get any (valid) hits from a million emails, maybe two million will do!