 This means that mail for these places is not fully sorted until it gets to Geelong.Some postcodes cover large populations (e.g., postcode 4350 serving some 100,000 people in Toowoomba and the surrounding area), while other postcodes have much smaller populations, even in urban areas.Australian postcodes range from 0200 for the Australian National University (now 2601) to 9944 for Cannonvale, Queensland.