Abstract: Control is executed in such a manner that storage and forward exchange can be performed even when a communication message comprising media information sent from a communication terminal exceeds a predetermined message length, thus improving the utilization efficiency of the system as a whole. Specifically, when a mailbox registration request message addressed to one terminal is received by a mail processing apparatus through a communication controller upon having been sent from another terminal via a network, a main controller determines whether the received message exceeds a predetermined maximum message length. If it does, then it is determined if a media classification is indicative of image information. In case of image information, it is determined by a media table whether the terminal for which the message is destined is capable of receiving the image information.