When data which cannot be processed is attached to an E mail routed to a terminal, an alternate URL for specifying the attached data is issued. A browser portion accesses a Web server utilizing the alternate URL. A data converter acquires from a mail server an E mail specified by mail acquiring information constituting a part of the alternate URL. That is, the data converter receives the E mail routed to the terminal in place of the terminal. The data converter specifies the attached data which cannot be processed on the basis of an attaching number in the alternate URL, to convert the attached data into data in a format which can be processed by the terminal. The converted data is transmitted to the terminal through the Web server. The browser portion displays on a display portion the data having the format which can be processed and refers a user to the data. Even if a terminal on the transmission side attaches to the E mail data, generated by application software, which cannot be correctly displayed by a terminal on the receiving side, therefore, the terminal on the receiving side can receive from the data converter data in a format which can be displayed and display the received data.