Tools for LARTing large nets of compromised boxen?

One of our customers is (has been) under concerted attempt at a DDoS attack against their web server off and on for a while. I've lists of IPs, lots of them, many hundreds. I'd like to know if anyone has a tool that will take and match these lists of IPs into abuse contacts and fire off a LART to the appropriate RP for the IP, but only one per full set, IE if RP-A has IP A.B.C.D and A.B.C.C he should get one mail clue-batting him for both IPs. Any help? TIA! -- "Genius might be described as a supreme capacity for getting its possessors into trouble of all kinds." -- Samuel Butler