An image processing apparatus capable of transmitting image data to an external device includes a display unit for displaying a list of information indicating transmission destinations to transmit the image data, a selection unit for selecting information in the list, a determination unit for determining whether the selected information satisfies a particular condition, and a transmission unit for transmitting, when the selected information does not satisfy the particular condition, the image data to the transmission destination indicated by the selected information, and transmitting, when the selected information satisfies the particular condition, information indicating that the image data has not been transmitted to the transmission destination indicated by the selected information. The transmission unit transmits, in response to reception from the external device received the information indicating that the image data has not been transmitted of a request to transmit untransmitted image data, the untransmitted image data to the external device.