1. An image forming apparatus capable of delivering image data, the image forming apparatus comprising: an image forming unit configured to read an image to generate image data; a workflow selection unit configured to receive selection of workflows each obtained by optionally combining input processing, image-conversion processing and output processing plug-ins for processing the generated image data; a storage unit configured to store data identification information for identifying desired electronic data; a data selection unit configured to receive selection of the desired electronic data; an electronic data acquisition unit configured to acquire the selected electronic data based on the corresponding data identification information; and a delivery processing unit configured to carry out delivery processing on the acquired electronic data and the generated image data based on a selected one of the workflows.