A mail sending and receiving unit provided to a terminal for person in charge receives inquiry mails to which uniquely identifiable receipt numbers are added, and reply mails sent in response to the inquiry mails. An e-mail storage unit stores the incoming e-mails received by the mail sending and receiving unit, and the receipt numbers added to the incoming e-mails. The mail sending and receiving unit sends reply e-mails which are created in response to the incoming e-mails stored in the e-mail storage unit, and to which the receipt numbers of the corresponding incoming e-mails are added. A management screen generation unit displays the inquiry mails stored in the e-mail storage unit, and the reply mails, as being associated with each other by use of the receipt numbers of the respective inquiry mails.