Abstract: A signal device is mounted on the inside of the door of a curbside mailbox. Opening and then closing the door closes a switch (mechanical switch, gravity actuated, a mercury switch or a photo diode) to emit a radio signal. A receiver in the residence, when actuated by the radio signal, notifies the occupant by an audible and/or visual signal.

Abstract: A signal to indicate deposit of mail in a box remote from a residence employs an optical reflective detector which senses presence of mail in the box. The transmission may be r. f. if the box is relatively isolated from other boxes. In apartments, condominiums, and the like where multiple boxes are centrally located, transmission may be by special wiring or by imposing a coded signal on house electrical wiring. Means is provided for the detector distinguishing between outgoing mail deposited in the box and new incoming mail.