the most common way to get emails for marketing from convention attendees at Con Expo was the ubiquitous drawings for Yeti coolers

there were so many that I found more than booth had a neighbor who was also using the same tactic

there were even coolers similar that weren't even bought or brought to try the same way of getting those necessary emails, but without the expense. Frankly, I doubt that any are given away, they don't prove it