An image processing apparatus that stores image data in a volatile memory, and also transmits data corresponding to the stored image data to a mail server by attaching it to an electronic mail addressed to the image processing apparatus. If it is detected, prior to an execution of an image processing such as printing, that the image data has been erased from the volatile memory due to a power failure or the like, the image processing apparatus acquires the data corresponding to the image data from the mail server and resumes the image processing job.