Abstract: A mailbox is provided with a lockable letter-mail compartment within in the form of a rectangular box having at least four sides and a hinged door with a key operated mechanism for locking it in the closed position, secured to the floor, side or roof of a mailbox for use in motorized delivery routes, or in the form of a shelf secured between side walls of the mailbox and a hinged door with a lock. The compartment has a slot for receiving letter mail without opening the door of the compartment. The slot is preferably in the locked door of the compartment. The height of the lockable compartment is sufficient to permit mail to be extracted through the hinged door, but of a height significantly less than the height of the mailbox to permit mail other than letters to be placed in the mailbox outside of the compartment.