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