To provide a technique for facilitating the management of an attachment file attached to an electronic mail. A client apparatus acquires attachment position information in a text of the electronic mail and stores it associated with an identifier of the electronic mail, in receiving the electronic mail with attachment file. Upon receiving an instruction for displaying the electronic mail from the user, the client apparatus arranges a graphic representing the attachment file of the electronic mail on a child screen that displays the reduced screen of a parent screen that displays the electronic mail based on the corresponding attachment position information, and displays the child screen together with the parent screen.