Rekeying a mailbox lock is an essential skill for homeowners, renters, landlords, and property managers. Whether you’ve lost your keys, moved into a new home, or want to improve the security of your mailbox, learning how to rekey a mailbox lock helps ensure privacy and protect your mail from unauthorized access. Although the process may sound technical, rekeying is surprisingly simple when you understand the steps and have the right tools.
This guide explains everything you need to know, including when rekeying is necessary, what tools you need, how to remove the old lock, how to install a new one, and common issues to avoid. To find high-quality replacement locks that match your mailbox model, explore our curated selection here: Mailbox Lock Collection.
Why Rekey a Mailbox Lock?
Rekeying your mailbox lock enhances security and ensures that only authorized people can access your mail. Here are the most common situations where rekeying is recommended:
You moved into a new home
Previous residents may still have a key. Rekeying ensures exclusive control.
You lost your mailbox keys
A lost key is a potential vulnerability, especially if your address is easy to identify.
Your mailbox was tampered with
If there are signs of forced entry or lock damage, rekeying restores safety.
You manage rental properties
Changing locks between tenants helps maintain privacy and security for new residents.
You want a more secure locking system
Upgrading to a newer or stronger mailbox lock can prevent break-ins and improve durability.
Tools You Need to Rekey a Mailbox Lock
Most mailbox locks are simple cam locks, which require only a few basic tools to replace or rekey:
-
Flathead screwdriver
-
Phillips screwdriver
-
Needle-nose pliers
-
Mailbox lock replacement kit
-
Lubricant (optional)
Some metal mailboxes may require additional tools like a hex wrench, but in most cases, rekeying is straightforward.
Understanding How Mailbox Locks Work
Before you start, it's helpful to understand the basic structure of a mailbox lock. Most modern mailboxes use:
-
A cam lock – a small cylinder with a rotating cam on the back
-
A retaining clip – holds the lock in place
-
A set of keys – usually 2 or more
-
A locking arm – rotates when the key turns
Since these locks are not high-security systems, they are designed to be easily replaced. Rekeying often means replacing the internal lock mechanism rather than modifying the key itself.
How to Remove an Old Mailbox Lock
Rekeying begins by removing the old lock. Follow these steps carefully to avoid damaging your mailbox.
1. Open the mailbox
Use the old key if available. If the key is lost, you may need to pick the lock or call a locksmith. If the mailbox is yours on private property, drilling is an option—but only as a last resort.
2. Locate the retaining clip
Inside the mailbox, you will find a small metal clip holding the lock in place. Use pliers to pinch and slide it off.
3. Remove the locking arm
Unscrew or unclip the small metal arm attached to the back of the lock cylinder.
4. Pull out the old lock
Once the clip and arm are removed, the lock slides out easily from the front.
How to Install the New Mailbox Lock
Once the old lock is removed, installing the new one is simple.
1. Insert the new lock cylinder
Slide the new mailbox lock into the opening, ensuring it fits snugly.
2. Attach the locking arm
Most lock kits provide multiple arm types. Choose the one that matches your mailbox and secure it with the included screw or clip.
3. Secure the retaining clip
Slide the retaining clip back onto the lock from the inside. It should snap firmly into place.
4. Test the lock
Insert the key and turn it to ensure the cam rotates smoothly and the door opens/closes properly.
5. Lubricate (optional)
Apply a small amount of graphite or lock-safe lubricant for smoother operation and longer lock life.
Rekeying vs Replacing: What’s the Difference?
Many people confuse rekeying with replacing. Here’s the difference:
Rekeying
Modifying a lock so it works with a new key.
For mailbox cam locks, this usually involves replacing the internal cylinder.
Replacing
Removing the entire lock and installing a new one.
This is often easier for standard mailboxes and achieves the same result in terms of security.
In practice, rekeying a mailbox lock often means replacing it, which is fast, inexpensive, and more efficient than altering the old mechanism.
Common Problems and How to Fix Them
The key doesn’t turn
This usually means the cam arm is installed upside down. Remove it and reattach correctly.
The mailbox door won’t close
The cam arm may be too long or misaligned. Choose a shorter arm from the kit.
The lock wiggles or feels loose
The retaining clip may not be fully snapped into place. Slide it in again until it locks firmly.
The key is hard to insert or remove
Add a small amount of graphite powder. Avoid oil-based lubricants, which attract dirt.
The new key still doesn’t work
Make sure the lock cylinder is fully inserted and not angled.
How to Choose the Right Replacement Lock
Selecting the right lock is essential for proper functionality. When choosing a mailbox lock, check:
-
Mailbox type (wall-mounted, post-mounted, cluster box)
-
Lock cylinder size
-
Cam arm length and shape
-
Whether the lock is USPS-approved
-
Material durability (brass, steel, zinc alloy)
To help you find compatible and durable models easily, browse our dedicated page: Mailbox Lock Collection
Safety Tips When Rekeying a Mailbox Lock
-
Only rekey your own mailbox or one you have legal authority over
-
Do not drill locks belonging to USPS or community cluster mailboxes
-
Wear gloves when handling metal parts
-
Ensure the mailbox is empty before working
-
Test the lock multiple times before finishing
FAQ – Frequently Asked Questions
Can I rekey a mailbox lock myself?
Yes. Most residential mailbox locks are simple cam locks that can be replaced with basic tools.
How long does it take to rekey a mailbox lock?
Typically 10–20 minutes, depending on your mailbox and experience.
Do I need to contact USPS to change my mailbox lock?
Not for private residential mailboxes. For cluster mailboxes, USPS handles the lock replacement.
What if my mailbox key is lost and I can’t open it?
You may need to pick the lock, call a locksmith, or carefully drill it out if it’s a private mailbox.
Can I use any cam lock for my mailbox?
No. You must choose the correct size and cam shape for proper operation.
Is rekeying the same as replacing the lock?
For mailboxes, the terms are often used interchangeably because replacing the lock is the standard method.