Abstract: A system for alerting mail distributors to a potential message (such as that all the current mail has been forwarded) when attempting to deliver mail to a mail receptacle. A device is provided which may be entirely located within such mail receptacle, which device permits the positioning of both alerting means and message means in a position demanding attention by such mail distributor. Alerting is accomplished by an enhanced sort of "miniature stop sign" and messaging is provided by a slotted holder for holding a replaceable message viewable through a transparent face of the message holder. Appropriate positioning of the alerting system within the mail receptacle is accomplished by a pair of spring-loaded extendible rods which may be retracted by the user to place the whole alerting system within the mail receptacle and then releasing the rods for compression contact with the inner walls of the mail receptacle.