An address list management apparatus stores, for each user of an MFP (Multi Function Peripheral), a different address list that lists address information pieces for transmission of image data by the MFP. Upon being instructed by a logged-in user to transmit image data, the MFP transmits, to the address list management apparatus, a request for the address list that specifies the user. Upon receiving the request, the address list management apparatus transmits, to the MFP, a sending list pertaining to the user. The sending list is created by deleting secret information from address information pieces in the address list, and modifying such address information pieces so that image data is transmitted to the address list management apparatus. The address list management apparatus refers to the address list, and transfers the image data to the specified address.