So that the electronic mail handling machinery could work effectively, a new postcode system needed to be designed. Different types of postcodes were already in use a few Australian states and cities, but the new system was designed to be used Australia wide and to simplify the sorting process. Coding operators on the new machinery keyed in the postcode which sorted the letters electronically, and then dispatched the mail to the delivery offices. 

On July 1, 1967 Australia's new postcode system was rolled out. Four digit numbers were allocated to every mail delivery area across Australia. The first number was based on radio call signs, then geographic progression from the major city. A postcode booklet was sent to every household and business address in Australia, listing nearly 5,000 postcodes.