Communication apparatus and method having electronic mail communication function, and program

There are provided a communication apparatus and method that enables the retransmission of an electronic mail if an error occurs in the transmission of the electronic mail due to its excessive data size, by reducing the data capacity of the electronic mail without taking time and labor, and a program for implementing the method. In a digital copying machine as the communication apparatus, when an electronic mail that notifies an error relating to an electronic mail transmitted with image data attached is received, the error notification electronic mail is analyzed. If an error that is attributable to the data capacity of the electronic mail is detected from the analysis result, the image data attached to the electronic mail for which the error notice has been received is acquired and the capacity of the image data is reduced by lowering its resolution. The electronic mail to which the image data thus reduced in capacity is attached is retransmitted.