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7.5″ wide Medium Locking Mailbox Insert

Original price was: $109.00.Current price is: $99.00.

7.5″ wide locking mailbox insert creates a locking compartment inside a standard common 8″ wide mailbox.  These are not vaults, but they do protect mail from a casual thief and it offers an excellent visual deterrent. Once a mail thief sees your lockbox, hopefully they move on to an easier victim.

Your mailbox opening MUST BE AT LEAST 7.75″ WIDE (left to right) otherwise this is NOT the correct item for you.

Move down for more info.  Click the TABS for info regarding USPS approvals and installation options.

In stock



Standard Installation
Column Installation
USPS Approvals

We sell different size locking mailbox inserts.  This page is for the 7.5″ wide size unit that is sold to customers with a mailbox that has an opening that is at least 7.5″ wide (left to right).

  • Locking mailbox inserts add a locking compartment to an ordinary standard medium size mailbox.
  • Sturdy construction with 14 gauge steel doors and 16 gauge steel bodies with stainless steel hinges.
  • Four high security keys included.
  • Mail gets pushed through slot.
  • Slot bent inward to restrict a hand from reaching in to easily steal your mail.

These are not vaults, but they do protect mail from a casual thief and it will offer an excellent visual deterrent. Once a mail thief sees your lockbox, hopefully they move on to an easier victim.


Measures approx 7.5″ wide x 5.75″ tall x 18.75 ” deep
Mail Delivery Slot size: 7.25″ wide x 1.5″ tall

Your mailbox opening MUST BE AT LEAST 7.75″ WIDE (left to right) otherwise this is NOT the correct item for you.

Shipping to the 50 States:

AK & HI deliveries…. add $20.00/lockbox


The video below provides a lot of extra information about locking mailbox inserts.

Standard Installation

Our locking mailbox inserts are fairly easy to install.  They get bolted to the mailbox floor.  We include the stainless steel mounting bolt with a matching lock nut.  Our locknut looks like a regular nut, except it has a vinyl threaded core.  Once the bolt and nut are tightened together, the vinyl threads make it impossible for someone to simply back-off the nut.  The vinyl grabs the threads of the bolt so tightly, any attempt to back-off the nut will result in the bolt/nut just spinning and spinning.  The only way to back-off the nut would be if you have a key to open the locking insert door, and hold the bolt head from turning.

Once you’ve placed the locking insert inside the mailbox and confirmed they fit well together, you’ll need to drill a 3/8″ hole in the mailbox floor to coincide with the hole in the locking insert hinge assembly.  Be sure that the insert is centered perfectly to avoid any possibility of the locking mailbox insert door from scraping against the side wall of the mailbox opening.  You can always fine-tune the mounting hole location using a “rat-tail” file.  Your goal is the have the locking insert mounted perfectly in the center of the mailbox opening.

Once the hole in the mailbox floor is completed, simply bolt the locking insert in place using the aforementioned bolt/locknut.  Tighten just until snug.  No need to clamp down and over-tighten.

And…  that’s it.  Your incoming mail has just become more secured.

Column Installation

We provide a bolt/locknut for attaching the locking insert to the mailbox floor. If the mailbox floor has about 1.5″ protruding out from the front of the brick, you can use the bolt/locknut we provide.

If not, then there is a brick in the way directly under the front/bottom of the mailbox and that will require a higher level of installation. This type of attachment would involve drilling a hole down into the brick that is just under the front of the mailbox floor using the hole in the locking insert hinge as a guide. Once the hole is drilled down into that brick, you will most likely insert a “molly” plug into that hole… and use the matching screw to fasten the locking insert in place.

You would need to pick up locally the hardware needed to make the attachment into that brick, and if you bring the locking insert into the hardware store, they would have a better idea of exactly what hardware would be best for you.

USPS Approvals

Only the actual mailbox itself gets USPS approval. A locking insert is an accessory to a mailbox and they do not receive specific approval.

Whether a locking insert can be used or not is entirely up to your local Post Office. In almost all cases, since mailbox lockboxes have been around for so many years, even the smallest lockbox is “OK” with the local USPS…. simply because mail-theft is not only a homeowner problem, it’s also a problem for the USPS.

Most local postmasters allow locking inserts simply because it cuts down on the mail theft problems they need to deal with…. but… problems can occur when local USPS people (whether it be the postmaster or the letter carrier himself) object to the use of a locking insert.  In that event, they’ll stop your mail until the locking insert is removed… and although it’s a rare situation, the USPS absolutely has the authority the demand the locking insert be removed.  In the 20+ years we’ve been selling locking mailbox inserts, we’ve heard of USPS objects only a few times, and most of those situations were the result of an already bad relationship between the home owner and the letter carrier.  It happens.

If you have mail theft concerns, I would ask your letter carrier for permission to use the locking insert. Chances are there are other locking inserts in your neighborhood. You can also speak with someone at your local post office and if they say yes… then you will not have any unexpected problem.

It is very important to explain that only letters go through the slot into the locking insert. Junk mail and larger items get placed in the unsecured area on top of the locking insert.

Feel free to call if you have any other questions or concerns.

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