Patent ID: 8102553

Claim:
A data communication system comprising an image processing apparatus and a data communication device, wherein said image processing apparatus comprises: a multicast transmission section for making an e-mail including identification information for identifying a multicast transmission and for executing a multicast transmission including a transmission of the e-mail and a transmission of information included in the e-mail under a communication protocol; and a history information generating section for generating history information showing the identification information and receivers of the multicast transmission identified by the identification information in connection with each other, wherein said data communication device is connected to said image processing apparatus via a network so as to be communicable with said image processing apparatus, said data communication device comprising: a first receiving section for receiving the e-mail sent by the multicast transmission; a first extracting section for extracting the identification information from the e-mail; a mail generating section for making a reply e-mail including the identification information; and a sending section for sending the reply e-mail to the image processing apparatus, wherein said image processing apparatus further comprises: a second receiving section for receiving the reply e-mail; a second extracting section for extracting the identification information from the reply e-mail; and a designating section for designating receivers of a reply multicast transmission based on the identification information and the history information, and wherein the multicast transmission section executes a reply multicast transmission to the receivers designated by the designating section.