In an e-mail operation system, an e-mail operation requirement having as a destination a first mail address used by a target terminal when communication with a first communication network is performed is received by a first e-mail control device included in the first communication network. In a first e-mail operation system configured to include the first e-mail control device and a SCP, the telephone number of the target terminal that is in association with the first mail address is specified. The e-mail operation requirement is transmitted to a second communication network using this telephone number. In a second e-mail operation device, an e-mail operation instruction is provided to the target terminal by using the telephone number that is required to be operated. Thus, the e-mail operation instruction is provided to the target terminal through the second communication network different from the first communication network.