A communication apparatus according to the present invention includes: upper limit setting unit, adapted to set a transmission upper limit which defines an upper limit of data size of mail data to be transmitted in a single e-mail; image data acquiring unit, adapted to acquire image data to be attached to the e-mail; transmission upper limit updating unit, adapted to update the transmission upper limit by subtracting a predetermined margin from the transmission upper limit; data dividing unit, adapted to divide the image data acquired by said image data acquiring means into pieces of image data corresponding to the transmission upper limit updated by the transmission upper limit updating means; divided mail data generating unit, adapted to generate divided mail data containing each of the pieces of image data divided by said data dividing means; and transmission unit, adapted to repeatedly transmit the divided mail data so as to transmit the e-mail to which the image data is attached.