Abstract: The invention related to a postcard or information carrier, comprising one or more peripheral sides capable of being folded onto a first side and joined, forming a receiving space for a data carrier, wherein the one or more peripheral sides cannot be opened unintentionally and the data carrier cannot be lost. The invention also provides a method of generating a customer database, comprising mailing or delivering a postcard to an addressee, wherein the postcard includes a reply postcard that requires information to be furnished by the addressee, and having a data carrier that includes information of interest to the addressee, receiving the reply postcard from the addressee, converting the information into computer-readable format to generate a customer database based on the information furnished by the addressee, and using the customer database to generate a mailing list to solicit or send further information or products to the addressee.