I can't see that you'll really lose that much business.
First, how many people on their "mailing list" (and who says that "CoRE" even *has* enough industry savvy to know who would be "high value" contacts and who isn't?) would really be likely buyers of your report in the first place.
Second, unless you've already done business with those companies in the past, odds are that most of the "mass mailings" will end up being looked at by some sysadmin flunky getting the "to no-one in particular" emails, who will either consider the mailing to be some sort of con-game spam and delete it, or at best figure it's worth exactly what the company has paid for it, i.e. nothing -- unsolicited emails seldom contain anything of real value.
Finally, any company who receives it who might actually be in the market for your reports is at least moderately likely to pay you for a legitimate copy if they like what they got illegitimately, or if nothing else will want to contact you to see what other similar products you offer.
So I wouldn't worry *too* much about lost sales, unless these jackasses managed to get a copy of your actual customer list, which I highly doubt.
They seem to have a good list from I could gather. Copies went to the industry's leading VC, a major technology analyst at Merril Lynch, GE's Lab and a few start-ups that I know. Yes, these types of people buy research. The note they sent out looks like it was us giving the report away which makes it very damaging. Maybe someone with half a brain would at least ask what the hell we were doing giving the report away but some people might just say, Thanks for the free stuff.
I accept that we got boned on this one but I am damn sure not going to roll over either.