An addition symbol to add two destinations selected from a list of destinations including a group name representing mail addresses of multiple members, and a subtraction symbol to subtract a mail address of an arbitrary member from a group destination are predefined in electronic mail software, so that when an electronic mail message is transmitted to multiple destinations from a communication terminal, the addition symbol or the subtraction symbol is placed between one destination and the other destination in a destination field in a window for composing an electronic mail message to add a destination address to or delete a personal address of a group member from a group name.