An object of the present invention is to provide a mail server that is capable of obtaining the information in a specific electronic mail efficiently. The mail server records an address notified by a mobile communication terminal as a recorded address, attaches automatic opening identification information to electronic mail, from among the electronic mail addressed to the mobile communication terminal, which has a transmission source address that matches the recorded address, and delivers this electronic mail repeatedly. When the mobile communication terminal receives electronic mail to which automatic opening identification information is attached, the electronic mail is opened automatically.