Data transmission device, data transmission method, data transmission program, data reception device, data reception method, data reception program, and communication system

摘要

In the present invention, after an image mail is transmitted to a receiving-end machine (S1, S2), when a reception error occurs, an image format of image data in the image mail is altered, and the image mail including this image data (retransmission image mail) is retransmitted to the receiving-end machine (S3 through S13). That is, it is attempted to avoid the occurrence of the communication error due to the image format, by altering the image format of the image data and retransmitting the same. With this arrangement, it is possible to avoid successive occurrence of the communication errors, even if the transmission data is retransmitted. Thus, as compared to the arrangements in which retransmission is not carried out at all or identical transmission data is retransmitted, the present arrangement can improve the efficiency of data transmission.