Home Postcodes by state WA 6336 Postcode 6336 6336 is the postcode for 6 localities in WA: Cowalellup, Mills Lake, Mindarabin, Needilup, Ongerup and Toompup. Localities with postcode 6336CowalellupWAMills LakeWAMindarabinWANeedilupWAOngerupWAToompupWA Postcode 6336 State or territory Western Australia (WA) Localities 6 Council area Gnowangerup; Jerramungup Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6335 · Postcode 6337