A server network includes a central server and a plurality of store servers. Each of the store servers is connected to one or more receipt printers. The central server selects one or more store servers to which image data of an image to be added to a receipt are distributed, and transmits the image data along with condition data to the selected store servers, which are then distributed to receipt printers. Receipt printers that received the image data print one or more receipts with the additional image upon the conditions being met, and transmit content data of each printed receipt to the corresponding store server. Each of the selected store servers generates a receipt issue log based on the content data, and transmits receipt issue logs that accumulated therein to the central server. The central server calculates an amount of exposure of the additional image based on receipt issue logs.