Abstract: A gravity operation flag indicator device for a mailbox is provided which includes a simple latching mechanism operable responsive to opening and closing of the door of the mailbox. The device includes a flag indicator which is pivotably mounted in a side wall of the mailbox and has affixed thereto a latching arm which is disposed inside of the mailbox. The latching arm is mounted adjacent to the mailbox door and is of such dimensions that when the latching arm extends horizontally, the end thereof will be engaged by the door when the door is closed and thus the flag indicator will be held in a horizontal position. When the door is opened by the mailman, the latching arm is automatically released from engagement with the door and the flag indicator falls by its own weight to a vertical position to indicate that the mail has been delivered.