A system includes an external apparatus, a server having an authentication function, and an image processing apparatus that communicate with each other via a network. The system performs user authentication in the server, for a user using the system, acquires apparatus information of the external apparatus from a printing request received from the external apparatus, verifies the apparatus information in the server, and executes printing in the image processing apparatus, based on the printing request from an external apparatus corresponding to the successfully verified apparatus information, in a case where the user authentication and the verification for the external apparatus are successful.