Check the Rules First

In Australia, Australia Post has placement guidelines for letterboxes: the box should be positioned so mail can be delivered without the carrier leaving their vehicle — typically within 2–3m of the property boundary, at a height of 900–1200mm from the ground for a kerbside box. Check with your council for any specific local requirements.

Method 1: Post-Mounted Letterbox

  • Post-mounted letterbox
  • Timber post (90x90mm or 100x100mm, treated pine) or metal post
  • Post-hole digger or shovel
  • Rapid-set concrete (1–2 bags)
  • Level
  • Screws and drill
  1. 1

    Mark and dig the hole

    Mark the post location. Dig a hole at least 600mm deep (deeper in sandy or loose soil). The diameter should be about 3 times the post width — roughly 250–300mm for a 90mm post. Call Dial Before You Dig (1100 in Australia) before any digging to check for underground services.

  2. 2

    Set the post in the hole

    Place the post in the hole. Check it is perfectly vertical using a level on two adjacent sides. Have a helper hold it while you pack with concrete or brace it temporarily with timber stakes.

  3. 3

    Pour rapid-set concrete and brace

    Mix rapid-set concrete as directed and pour around the post. Tamp to remove air pockets. Form a slight mound above ground level so water drains away from the post base. Brace the post in position and let cure — rapid-set takes 20–60 minutes to set initially but allow 24 hours before loading the post.

  4. 4

    Attach the letterbox to the post

    Once the concrete has cured, attach the letterbox to the post using the hardware provided or with appropriate screws. Check it is level and at the correct height. Add a house number.

Method 2: Wall-Mounted Letterbox

Hold the box against the wall at the desired height and mark the mounting hole positions. Drill through brick or rendered masonry with a masonry bit. Insert wall anchors. Screw the box securely to the wall. Check it is level before tightening fully.

Post protectionPaint or seal the bottom 150mm of a timber post (the section in the ground) with a bitumen-based sealer before setting — this dramatically extends the life of the post by preventing moisture absorption and rot.

Frequently Asked Questions

Minimum 600mm deep for a standard mailbox post. In areas with strong winds or loose sandy soil, go deeper — 750–900mm provides better stability. A general rule is that one third to one quarter of the total post length should be underground. For a 1.5m above-ground post, set 500–600mm in the ground.
Australia Post guidelines specify letterboxes should be accessible from the delivery vehicle (kerbside) or at the front of the property, with the opening facing the delivery path. Height should be 900–1200mm from the ground. Some councils have regulations on placement and appearance — check with your local council before installing a large or distinctive letterbox.