Systems, methods, and software that enable a remote host computer in receipt of a client transmission to reject subsequent redundant or duplicate transmissions from the client. The invention provides systems, methods, and software for attaching unique identifiers to transmissions sent to a client by a host computer. Upon sending the transmission with the attached unique identifier to the client, the host computer stores the unique identifier. The invention further provides methods, systems, and software for attaching the same unique identifier received by the client from the host computer to the particular client transmission that is responsive to the particular host computer transmission. Comparison of the unique identifier attached to the client transmission with stored unique identifiers allows the host computer to reject redundant transmissions.