Almost all junk mail distribution companies belong to the New Zealand Marketing Association. Members voluntarily adhere to the Code of Practice – Distribution of Unaddressed Mail.
The 2014 revision of the code states:
2.1 Unaddressed mail must not be delivered to letterboxes where a sign requesting”Addressed Mail Only” is displayed;
NB: Public notices from Government bodies and local authorities and election material are permissible.
2.2 Unaddressed mail – must not be delivered to letterboxes displaying a No Unaddressed Mail:, “No Junk Mail”, or”No Circulars” sign.
NB: Public notices from Government bodies and local authorities and election material are permissible, as are community newspapers or magazines, communications from local citizens groups and charities.
2.3 Unaddressed mail must not be delivered to addresses where there is no letterbox or where the letterbox is unsuitable for receiving or holding such material;
2.4 Unaddressed mail must not be delivered to letterboxes that are already full;
2.5 Other mail/material already in the letterbox must not be removed to make space for unaddressed mail;