A transmission management system includes a memory that stores destination information indicating destination candidates of a request source terminal, a receiver that receives a destination registration request designating one or more destination terminals as the destination candidates, processing circuitry that, when approval of the destination registration request can be omitted, registers one or more request destination terminals in the destination information as the destination candidates, and a transmitter that, when the approval of the destination registration request cannot be omitted, transmits the approval request to the one or more request destination terminals. The receiver receives a response to the approval request from the one or more request destination terminals. The processing circuitry registers the request destination terminal in the destination information of the request source terminal as a destination candidate.