A transmission side terminal 10 is provided with a transmission and reception unit 20 for transmitting and receiving an e-mail and an e-mail composing unit 32 for composing an e-mail including a special character for inquiry having associated therewith an information reply request, which is to obtain information on a destination mobile terminal of the e-mail to be transmitted. A reception side terminal 10 is provided with the transmission and reception unit 20, a determination unit 34 for determining whether a received e-mail includes a special character for inquiry, and a reply e-mail composing unit 32, when it is determined that the received e-mail includes the special character for inquiry, for composing a reply e-mail including a special character for reply with which reply information in accordance with the information reply request is associated.