Installing a High-Security Locking Mailbox on a Sloped Mailbox Location

Bellingham Mailbox •

Sometimes the challenging part of a mailbox installation isn't the mailbox itself, it's the location.

For this project, the homeowner had been wanting to upgrade to a high-security locking mailbox for quite some time. After finding Bellingham Mailbox online, they reached out to have a new mailbox professionally installed.

The existing mailbox had an interesting history. At some point, it had been struck by a vehicle and knocked over. The person responsible replaced the mailbox afterward, but rather than properly securing the new post in concrete, it had simply been buried directly in the ground.

While that approach got the mailbox standing again, it wasn't designed for long-term durability.

Understanding the Mailbox Location

One detail that may not be obvious from the photos is that the mailbox location sits below the elevation of the road on a sloped embankment.

When installing a mailbox on uneven terrain, post depth and final mailbox height become especially important.

USPS installation requirements specify that the bottom of the mailbox or point of mail entry be positioned 41" to 45" inches above the road surface.

The measurement is taken from the road surface, not necessarily from the ground directly below the mailbox.

On sloped sites, it's possible to install a mailbox that looks correct from the yard but sits too low or too high relative to the roadway.

Why Post Burial Depth Matters

Many mailbox installation problems begin below the surface.

The standard heavy-duty steel mailbox post used for this installation is 43" inches long. Under normal site conditions, that's sufficient for most installations.

However, because this mailbox location sat below road grade, a deeper burial depth was needed while still maintaining proper mailbox height.

To accomplish that, I lengthened the post by welding a reinforced rebar extension to the bottom of the post. This allowed for approximately 24" to 30" inches of burial depth while maintaining USPS-compliant mailbox height above the roadway.

Deeper burial depth helps:

  • Improve stability
  • Reduce future leaning
  • Better resist soil movement
  • Increase long-term durability

For homeowners installing their own mailbox, it's also worth noting that Mail Boss offers bolt-on post extension kits that can achieve a similar result without requiring welding equipment.

Installing the New Mailbox Post

Once the post was properly configured for the site, I installed it in concrete and carefully checked the alignment to ensure it was plumb.

Taking the time to properly align a mailbox post during installation pays off later. A mailbox that starts perfectly straight is much more likely to remain straight for years to come.

After the concrete was in place and the post was secured, the installation was ready for the new mailbox.

Installing the Locking Mailbox

To complete the project, I mounted a Mail Boss Mail Manager Pro high-security locking mailbox.

The homeowner's goal was simple: create a more secure mail delivery location that would better protect mail and small packages while also providing a sturdier installation than what existed previously.

Compared to the original mailbox setup, the new installation offered:

  • A heavy-duty reinforced steel mailbox post
  • Concrete-supported foundation
  • Improved stability
  • Locking mail security
  • Better long-term durability

The Finished Result

What started as:

  • A mailbox previously damaged by a vehicle
  • A post buried directly in dirt
  • An installation on a challenging sloped location

became:

  • A reinforced steel mailbox installation
  • Proper post burial depth
  • USPS-compliant mailbox height
  • A Mail Boss Mail Manager Pro locking mailbox
  • A sturdier and more secure long-term solution

Projects like this are a good reminder that mailbox installations are about more than simply setting a post in the ground. Site conditions, mailbox height, and foundation depth all play an important role in creating an installation that will remain secure and functional for years to come.

Learn More About the Products Used

Want to learn more about the products used in this installation?

Watch our YouTube product reviews and installation videos here:
Mail Boss Mail Manager Pro
Heavy-duty Steel Post

The Mail Boss Mail Manager Pro, heavy-duty steel mailbox post, and Mail Boss post extension products are also available through our online store:
Mail Boss Mail Manager Pro
Mail Boss Heavy-duty Steel Post
Mail Boss Post Extension