An electronic musical apparatus M1 transmits apparatus ID information and a common mail page access signal to a server computer SC. The server computer SC receives the signal and apparatus ID information. On the basis of the apparatus ID information, the server computer SC searches a user database 206a to identify the mail box of the user of the electronic musical apparatus M1. The server computer SC also searches an e-mail database 206b to retrieve an e-mail message stored in the identified mail box. The retrieved e-mail message is adjusted in accordance with display capabilities of a display unit 13 of the electronic musical apparatus M1. The server computer SC then transmits the retrieved e-mail message to the electronic musical apparatus M1. The user of the electronic musical apparatus M1 is allowed to easily read e-mail messages on the display unit 13.