Abstract: A system automatically changes the user data such as e-mail address registered in reception designation lists used in a reception designation service according to notification of user data change. Reception designation service lists are provided for storing user data of each of users of a reception designation service. A first server has a capability of sending a notification of user data change according to a request from a terminal device of a user, the notification containing a change from a former user data to a new one. A second server has a capability of receiving the notification and changing the former user data to the new one in a corresponding one of the lists to the terminal device according to the notification. When the corresponding one of the lists is set to be changeable, the second server changes automatically the former user data to the new one in the corresponding one of the lists.