To back up facsimile reception data without depending on a storage capacity of the facsimile machine.

Upon receiving facsimile reception data (image data) from another facsimile machine, a facsimile machine encodes the received data into a text data format of an electronic mail. The encoded image data are backed up to a mail server 140. The backed-up mail data are transferred from the mail server 140 to the facsimile machine. If the image data size is large, the image data are divided into a plurality of mail data on the basis of a predetermined dividing size, and backed up to the mail server 140. The plurality of backed-up mail data are transferred from the mail server 140 to the facsimile machine, and decoded on the basis of an encoding method and the image data are each composited.