Multinational Species Conservation Funds Semipostal Stamp Reauthorization Act of 2019 This bill directs the U.S. Postal Service (USPS) to sell each copy of the Multinational Species Conservation Fund Semipostal Stamp and notify Congress when all copies have been sold. If the USPS destroys one or more such stamps before this bill's enactment, it shall print and sell the same number of such stamps.