A Roadside Mail Box or RMB [1] is an artificial address that is created by Australia Post to deliver mail to a rural or remote location.
Without the RMB system, many intended destinations would otherwise be specifiable only by a series of directions or some other unwieldy, abstract description.
The RMB address functions similarly to a post office box in that it describes an intended addressee with a unique number, but it is different in that it aliases a real physical address rather than a container at a post office.
RMBs are usually located on the main road, and not on the farm.
The boxes themselves are often decorated as animals, birds or even daleks.