The issue is a 'no-brainer' for truly fraudulent 'customers'.
BUT, you better have a lawyer explain your legal exposure, should any of your facts be wrong or should you cause any actionable damages by sending the letter.
eg. You send the letter to the wrong person (if they can spoof IP's, addresses, especially for stolen CCs are even easier to fake).
eg. The customer's spouse (not related to the transaction) gets the letter and has a heart attack or stroke, or uses it in a divorce settlement resulting in huge losses.
eg. The letter gets discovered at work and a substantial job/contract is lost - worth much more than 1000 times your membership fee.
I believe that cheaters should be held accountable, but let's not get sloppy and wreckless in the heat of the moment.
It's always easy to jump on the 'posse bandwagon' and unfortunately, it usually takes an innocent victim to sober everyone up into a more considered approach.
Frankly, for those of you (and I'm not suggesting anyone in particular) who lack the ethics and respect for your visitors, by trying to cheat/bypass their popup blocker settings, and whine you get cheated back, STFU!
-Dino