Ah very cool. Tangentially related: I've been helping a client get some affiliate marketing set up, and the email-based affiliates require CAN-SPAM compliance. Basically, this requires a generic unsubscribe link where people can put in their email address to be added to a "suppression file" blacklist, which the affiliates can then download. It's intended to act as a shared blacklist when you're working with multiple affiliates, but I'm wondering what's to stop someone from just harvesting suppression files?