Step 1: Purchase replacement post, check town regulations and remove old post
The replacement mailbox post should have weather-resistant properties; pressurized pine and cedar are two good options. Check with your town for requirements on post height and distance from the road. Use a tape measure to ensure accurate placement and dimensions of the new post. Remove the old post by wiggling it back and forth to loosen it, and then pull it out of the ground. If the old post is fixed in cement, use a spade and shovel to dig it out.
Check for town regulations on height and placement of the new post.
Step 2: Prepare the post hole
Use a spade, long-handle shovel or post hole digger to widen the existing hole to about twice as wide as the old post. Hole depth should be deep enough to place the new post at regulation height plus four additional inches for a bed of gravel. Fill the bottom of the hole with four inches of crushed stone to allow for drainage. Wet the sides of the hole and the crushed stone to prevent the cement from cracking.
Use a post hole digger to widen the existing hole.
Step 3: Set the new post and pour cement
Set the replacement post in the hole. Use a level to ensure that the new post is level and plumb. Follow the instructions with the cement to mix it in a bucket until it is the consistency of pancake batter. Pour the cement evenly around the post and stir the cement with a stick to release any trapped pockets of air. Check once more to ensure a level and plumb post.
Stir the cement with a stick or a spade to release trapped air.
Step 4: Clamp the post and let cement set
Use two lengths of wood to clamp the post in place. Allow the cement to dry for 24 hours. Remove the clamp.
Clamp two pieces of wood to the post.
Step 5: Plant grass and install mailbox
Fill the rest of the hole with dirt. Lightly sprinkle the area with grass seed. Work the seed into the soil and set it in place with your foot. Lightly water the new seed, and leave the area undisturbed for 24 hours. When the cement has hardened completely, install the mailbox.
Sprinkle grass seed on the soil.