Short answer
A mailbox post almost always fails at the ground line. Look at the broken wood: light and solid means something hit it, and a hit post can often be reset or replaced in one visit. Dark, soft and crumbly means rot, and the rest of the buried wood is going the same way, so the post gets replaced. The mailbox itself usually survives either way and goes back on the new post.
Tell a hit post from a rotted post in five minutes
- Push the post near the top with one hand. Watch the ground, not the box.
- Note what moves. A post that pivots in the soil is loose in the ground. A post that flexes above the soil is cracked.
- Look at the break face if the post is snapped. Light, splintered wood means impact. Dark, damp, crumbly wood means rot.
- Push a screwdriver into the wood at the ground line. If it sinks in more than a quarter inch with light pressure, that wood is rotted.
- Dig 3 inches of soil away from the base and repeat the screwdriver test below grade. Rot starts below the surface and works up.
- Grab the mailbox and the bracket on their own. Check whether the box, the arm, or the fasteners are damaged separately from the post.
If the wood is solid everywhere and the post only pivots in the soil, the hole has opened up and the post can be reset. If the screwdriver sinks in anywhere at or below the ground line, the post is done and needs replacing.
Repair or replace
| Situation | What to do |
|---|---|
| Post wobbles, wood is solid at and below the ground line | Reset it. Dig the hole out, plumb the post, and tamp the backfill in 4-inch layers. |
| Snapped at ground level, break face light and solid | Replace the post. The buried stub has to come out, so there is no shortcut to resetting it. |
| Wood is dark, soft or crumbly at the ground line | Replace the post. Rot below grade never stops, and a patch above it fails in a season. |
| Post solid, decorative arm or bracket broken | Replace the bracket. Match the bolt pattern to the existing box. |
| Post solid, mailbox dented or the door hangs open | Replace the box only. Standard boxes bolt to the same platform. |
| Post set in a large concrete collar and leaning | Replace the post and break the concrete out. Set the new post in tamped soil or gravel. |
| Post leans again within a year of being reset | Replace it. Repeat leaning means the wood below grade has lost strength. |
What it costs
Runhome contractor estimates for this job, including the trip and assessment.
| Option | Range |
|---|---|
| Stabilize a leaning post and repair the support | $170 to $465 |
| Replace a snapped post and remount the existing mailbox | $230 to $575 |
Can I do it myself?
Yes, for most posts. A 4x4 replacement is a two-hour job with a post hole digger, a level and a bag of gravel. Call 811 first and wait for the locate, because cable, gas and irrigation lines run close to the curb and the utility marks them free. Set the post no more than 24 inches deep and skip the heavy concrete collar. Federal roadside rules want a mailbox post to give way when a car hits it, and a deep concrete block does the opposite. Mount the bottom of the box 41 to 45 inches above the road surface, with the face 6 to 8 inches back from the curb.
Hire someone if the old post is set in concrete, if the box sits on a brick or masonry column, or if the post is inside a road right of way where the county sets the rules. A leaning post beside a live traffic lane is also a hire.
What a contractor will ask you
Have these ready and you skip the back-and-forth.
- A photo of the whole mailbox and post taken from a few steps back, so the mounting and the ground are both in frame.
- How it failed. Snapped off at the ground line, pulled out of the ground with the base intact, or still standing but leaning.
- What the break looks like now. Mostly solid and light-colored, or dark, crumbly and soft.
- Whether the post wobbles when you push near the top.
- The age of the setup, even roughly.
- Whether the ground there stays wet and soft or is usually dry and firm.
- When the impact happened, if something hit it.
- What the post and box are made of. A 4x4 wood post with a rural box is a different job from a decorative metal assembly.
Last reviewed .