The current thread got me interested too.
If anyone is interested, I found the following that might help.
Steve Atkins' blcheck
http://www.samspade.org/w/blcheck/
The page has this.
"A freely distributable procmail helper utility for blacklist checking"
Edward S. Marshall's rblcheck
http://rblcheck.sourceforge.net/
Chip Rosenthal's blq
http://www.unicom.com/sw/blq/
Nick Craig-Wood's Filter
http://perlmonks.thepen.com/74023.html
I'll check those, and maybe be able to report back what are the results.
Hope this helps someone interested,
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