Abstract: A retrofittable mailbox light system is provided including mailbox and a housing having a releasable coupling mechanism mounted on the housing for allowing the housing to be mounted to an inner surface of the mailbox such that a front face of the housing remains flush with the open front of the mailbox. A lamp is mounted to the housing for illuminating the interior space of the mailbox only upon the receipt of power. A battery is positioned within an interior space of the housing. Also included is a momentary switch mounted to the housing and further connected between the lamp and the battery. The switch is adapted for supplying the lamp with power only upon the release thereof when the lid of the mailbox is opened.