To make a user of portable telephone terminal who can not see the contents of an attachment file in an E-mail, able to see the contents.

When the attachment file exists in a reception mail to a portable telephone set 10-1, an exclusive mail server 60 transfers the mail comprising the attachment file to a transfer destination mail server 80, adds the file name of the attachment file to the text contents of the mail and transmits a mail where only text sentences from which information of the attachment file is erased are corrected to the portable telephone set. In the portable telephone set, the received mail is displayed comprising an attachment file name so that the user recognizes the existence of the attachment file. When the attachment exists, the user performs access to a transfer destination mail server from the data terminal of PC 20, etc., through the portable telephone set, opens the attachment file by the application of a data terminal and can confirm the contents.