We too have already been offered these lists. You can be assured that this is a SPAM email. Please ignore them and do not respond to them.
A typical wording reads:
“Dear Exhibitor,
Are you interested in acquiring the “Scuba Digital” Post Attendees list? Let me know your thoughts, so that I can send more info on this like cost, counts, and samples.
Regards,
Varying names
Marketing Executive”