A mailing list is created including destination addresses for mailpieces to be submitted to a carrier service for delivery. A unique mailpiece identifier associated with mailpieces on the mailing list is generated by the carrier or other trusted third party. The unique mailpiece identifier is printed on the mailpiece with which it is associated. The mailpieces with the printed unique identifier are submitted to the carrier service. The carrier service obtains the printed unique identifier from the mailpiece. The obtained unique identifier from each said mailpiece is utilized to verify that data associated with the mailpiece has been processed by the carrier or trusted third party. When the unique number has been obtained from the mailpieces, the carrier service, if desired, may note this fact in the carrier records to prevent reuse of the unique identifier.