You should always include the postcode on an envelope to make sure your letter is sent to the right place. Every town and suburb has a postcode – some towns have the same name, but they have different postcodes. Or sometimes some smaller towns or suburbs have different names but the same postcode.

Write the postcode numbers inside the orange squares in the Post Office Preferred envelopes. If you're typing the address, you don’t need to use these squares, but the postcode should be on the last line of the address, next to the suburb and state.

You can collect a Postcode book from your local post office. Postcodes are also available at the back of the White Pages telephone directory and from the home page of the Australia Post website.