Home Postcodes by state WA 6252 Postcode 6252 6252 is the postcode for Mullalyup, WA. Localities with postcode 6252MullalyupWA Postcode 6252 State or territory Western Australia (WA) Localities 1 Council area Donnybrook-Balingup Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6251 · Postcode 6253