What is a good way to tell if a direct response package has been opened?
We are sending little gifts to some of our 'high roller' customers. How can we tell if a package has been opened? That way we can send the right follow up based on if it has been opened or not. We are using the USPS certified mail option to make sure the package is signed for but we also want to know, of the ones received, how many were opened and by who? Any simple, inexpensive solutions for this?