Exitfiles... tell us more

I have heard of using exitfiles to trace a spammer back to their true 
address.

I've been unable to find any references for this in order to begin
creation of procmail recipes.... essentilly at this point I'm clueless.


Any hints?
-- 
John L. Wilkerson Jr.               jwilkers(_at_)netcom(_dot_)com
                          http://members.tripod.com/~jwilkers/index.html

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