Definition of corner card

colloquial term for the promotional graphics and copy, as well as the return address, on an outer envelope; also called teaser copy. Many consider the corner card to be the most important element of a direct-mail piece because it entices the recipient to open and read the package. The copywriter should be careful not to use misleading corner card copy that doesn't truthfully represent the contents of the envelope. Widely used corner cards include "Valuable coupons inside" and "Dated Material."