A method of modifying the output of an output device is provided. A first code, associated with a first recipient party, is received and used to generate, within the output device, a second code, the second code containing encoded data identifying the first recipient party and instructions for activating an additional functionality of the output device. The additional functionality is activated in accordance with the instructions contained in the second code. The output of the output device is modified according to data encoded in the second code, to encode a third code in the output of the output device, the third code including an ID code associated with the first recipient party.