mate you've placed on it a return address and/or a phone no. as per directions.
Australia don't care for zip codes but with a postcode she'll be right.

Australia post has a rather hit or miss approach to mail. What with the Post offices being independantly run, the postmen working for Austpost and the parcel delivery persons being subcontractors.

As long as the post code was correct, and the street name and number. The machines don't even look at the place name when they are sorting!

as long as the ZIP code is right the parcel shouldn't get lost...in the case the ZIP code is wrong it will probably get lost

Postcode will get it to the correct post office. Parcels are sorted by numbers, not names. Lots of people make spelling errors and the mail still gets there.