A system and method to provide identification codes to track outbound mail and corresponding replies. Tracking is enabled where an intended recipient is not determined until after physical components of the mailpiece are assembled. A first ID code is associated with a second ID code on a return envelope. The first ID code is positioned on a front of the return envelope proximal to a return address on the return envelope. The second ID code is positioned on a back of the return envelope proximal to a recipient address region on the return envelope. The return envelope is inserted into a carrier envelope with the front of the return envelope facing the back of the carrier envelope, and the second ID code and the recipient address region being visible through a front window in the front of the carrier envelope. A recipient address is printed in the recipient address region of the reply envelope, through the front window on the carrier envelope. To allow mail piece tracking, the first and second ID codes are associated with the intended recipient of the outbound mail.