"They all find out that you opened the mail and they get an invisible tracking number, so if you go to a store ... that number is reported to them and they can build that information into a database, " Catlett said.
We continued to a backstage area where mail trucks shared space with production crews at banks of monitors tracking the party already under way, as well as Mr. Craig's progress.
Audio Ads also enables advertisers to track when and where their ads ran soon after the fact, providing them with a faster and more accurate way of tracking their spots than the usual invoices they receive via snail mail.