1. A data processing apparatus, comprising: a storage unit including a plurality of storage areas, each being assigned identification information identifying the storage area, and each being configured to store one or more images; a first selection unit configured to select a plurality of images from among images stored in at least one storage area selected from among the plurality of storage areas of said storage unit in response to an operation on an operation unit; a transmission unit configured to transmit the plurality of images selected by said first selection unit; a designation unit configured to designate a number of thumbnails to be presented on each page of a thumbnail list to be generated as an image transmission history in response to an operation on the operation unit; a thumbnail generation unit configured to generate thumbnails of the plurality of images selected by said first selection unit, and also configured to extract thumbnails from the plurality of images selected by said first selection unit when said transmission unit transmits the plurality of images; a thumbnail list generation unit configured to generate a thumbnail list that consists of thumbnails of the plurality of selected images using the thumbnails generated or extracted by said thumbnail generation unit in accordance with the number of thumbnails designated by said designation unit, sizes of the thumbnails presented on the thumbnail list being automatically adjusted based on the number of thumbnails designated by said designation unit, the thumbnail list being provided for each transmitted image with (a) transmission time information and destination information for the transmitted image and (b) the identification information for the storage area storing the transmitted image; and a print unit configured to print the thumbnail list generated by said thumbnail list generation unit so as to allow the user to check the plurality of images transmitted by said transmission unit, wherein said thumbnail list generation unit generates the thumbnail list and said print unit prints the thumbnail list in response to a transmission of the plurality of selected images by said transmission unit.