A communication apparatus communicates with an external apparatus, and executes instructions to set, as a transmission destination, at least one of first transmission destinations included in a first address book stored on the communication apparatus and second transmission destinations included in a second address book stored on the external apparatus, display detail information of the set transmission destination, and receive an instruction via a registration button to register the transmission destination in the first address book, when at least one of the second transmission destinations is set as the transmission destination and the set transmission destination is usable in the communication apparatus. According to the received instruction, the set transmission destination is registered in the first address book, and electronic data is transmitted to the set transmission destination. When the set transmission destination is unusable in the communication apparatus, registration using the registration button is not performed.