A mobile terminal includes a display and a controller. The display outputs a first input window configured to receive a first message. When input data is received into at least one message field of the first input window, the controller determines whether or not the input data conforms to a format of the first input window corresponding to the first message. The controller also outputs a notification after the input is determined not to conform to the format corresponding to the first input window corresponding to the first message. The display outputs a second input window to receive a second message. The second input window has at least one message field different from the message fields in the first input window.