COMMUNICATION SYSTEM, COMMUNICATION APPARATUS, COMMUNICATION SERVER, COMMUNICATION METHOD, INFORMATION STORAGE MEDIUM, AND PROGRAM

In a communication system (1), a communication server (20) determines whether to allow or disallow each of communication apparatuses (10) to send message data and send the communication apparatuses (10) a notice indicating the determination result. A communication apparatus (10) that is allowed to send accepts an input of message data from a user and sends the message data to the communication server (20), and the other communication apparatuses (10) that are disallowed do not accept the message data. When all the communication apparatuses (10) are allowed to send message data, the communication server (20) receives message data from all of them and sends the message data thereto. When some of the communication apparatuses (10) are allowed to send message data, the communication apparatus (20) receives message data only from the allowed communication apparatuses (10) and send the message data to all the communication apparatuses (10).