Home Postcodes by state NSW 2557 Postcode 2557 2557 is the postcode for 3 localities in NSW: Catherine Field, Gregory Hills and Rossmore. Localities with postcode 2557Catherine FieldNSWGregory HillsNSWRossmoreNSW Postcode 2557 State or territory New South Wales (NSW) Localities 3 Council area Camden; Mainly Liverpool, partly Camden Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 2556 · Postcode 2558