Replacing a Mailbox lock is simple even if you’ve never done it before and/or can’t get into it. Let’s review the process with images to guide us.

Recently I moved into an older home and found the mailbox key had issues opening the lock. After a few weeks, the mailbox key refused to open it. Great! No matter what I tried (graphite powder and spray included), after a few days of not getting my mail, I knew it was time to replace the lock.

Although we frequently focus on Technology, I love handy DIY tricks, so I thought I’d share this little adventure I had a few days ago. I started the adventure by calling my local post office, and that was a waste of time. They suggested a local locksmith and hung up on me. Yelp pointed me at a local locksmith who quoted me $250 for an onsite replacement plus an additional $150 an hour after 30 minutes.

So yeah, you can guess the path we’re going to take on this one. Time to get medieval on the mailbox lock!

Thankfully I have a cordless drill, so I grabbed a bit that fit nicely into the keyhole of the lock. The primary goal here is not damaging the housing holding the lock, so don’t use a lot of pressure when drilling into the lock. Just drill straight and apply consistent pressure.

Note: If you’re not the adventurer / handy type or don’t have a drill, wait for your mail carrier. They will have access to the back of the mailbox, and you can perform the steps below from inside the box. It’s not nearly as fun, but that is another option.

Once you drill through the entire lock mechanism, the mailbox door should open easily.

Slide the lock bar and metal clip holding the lock mechanism against the door. In some cases, the lock nut may still be attached to the lock. Use a wrench to take off the nut (although, in my case, the drill took care of that for me).

Without the clip holding the lock in place, popup the entire mechanism and bring it to a local locksmith. In my case, although my original lock was 15-years-old, he had an exact match that cost me just $12. However, if you cannot find a local locksmith (or don’t have time), grab a replacement mailbox lock from Amazon. The National Mailbox Lock C9100 should do the trick for clockwise rotation or the C9200 for counterclockwise.

Note: If you’re an HOA or Apartment complex and need more than one lock, here’s a link for the C9100 lock or C9200 in bulk.

Once you have the new lock, slide it into the lock housing the reattach it in a locked configuration (lock bar out).

Screw on the nut, and you’re done!

The new mailbox lock I purchased was a bit sticky. I solved this with a little Graphite Powder. Amazon has it listed for ~$5; however, I found it at a local HW store for under $2 the next day.

In all, the entire job took no longer than 5 minutes (not counting the trip to the locksmith). Not bad, considering the quote from the locksmith $250. I’ve always enjoyed DIY projects, especially the ones with a drill involved. It’s an excellent bonding opportunity for my son and me and a good way to show with a little work; almost any job is possible with a little time and patience.

Since publishing the DIY mailbox lock fix, several readers have expressed concern about the legal aspects of fixing your mailbox lock yourself. Although I can’t give legal advice , I did find a page on USPS.com regarding mailbox maintenance. Along with a guide on how to install a new mailbox, it also guides maintenance.

Mailboxes take a beating from the weather, so we recommend an annual mailbox checkup to avoid damage to your mail or difficulty identifying your address.

Based on this information directly from the United States Postal Service, it’s clear that the responsibility for maintenance and care of the mailbox falls on the property owner/manager.

I like it. We dont have those mailboxes but just started wireing our whole house with CAT6 including HDMI over CAT6 and its clear that technology and DIY often go hand in hand. In my case followed by a spot of first aid.

Sadly this is not an option for me. The mail person actually threatened to call the police and have me arrested when I tried to follow the “wait for mailman” part. Despite having an ID which listed the exact residence which matched the box I required to be opened. The postal office itself told me if I opened it by any means other than my assigned key that mail would no longer be sent to me, and I would have to start picking it up via the postal office branch. Then told me they could have one made for me in “as little as two weeks” and they would hold my mail for me at the local branch, and I could start going to pick it up all the way out there. Every day. And it would only cost me 150 dollars. Entirely bullshit. The postal service is taking their near federal mandated monopoly on daily mail service to a nice half assed level.

This is so illegal do not stick a drill into your mailbox! If anyone were to report you doing that you’d be a felon.

I called my post office and they told me I could replace it myself. Are you sure?

Good luck getting the post office to come out and help you with relocking mailboxes. You are subject entirely to the vagaries of the local post office. Drill them out and replace them yourself once you’ve failed to get the post office to help. If they do help you, you are one of the lucky ones.

USPS told me to check with HOA first, and if it’s not their responsibility, to check with USPS to find out if it’s their responsibility or mine. So I bought a lock and I replaced it. Each lock comes with five different latches and one them matched my old lock

Great to hear Samir — Great to hear you got it fixed and replaced. Thnx for the update.

If one drills into their own mailbox, that they purchased themselves, and is free standing or on the owner’s property, you’re fine. The contents of the mailbox belongs to the owner who installed the mailbox. As for those who live in condo/apts. or have mailboxes which are attached to each other,, where there is an HO association, the law may be different and that may cause general concerns. As for the PO, in many cases, they are worthless, though there are some stars here and there. If the local PO would have let us insert a garage slot, as we wanted in the first place, we wouldn’t even need a key! But, our home was new construction and the PO didn’t want their carriers to “waste” their time, having to walk up the driveway to the garage door, when they could just hop out of their golf carts and shove the mail into the box. At the time, our mailman would have gladly walked the mail to our garage, but any sub or new carrier …who knows? The days or common sense and decency are long gone!

I suppose it could vary from state to state but from what I’ve read.. once a mailbox is put into use by the post office, it is federal property. If you tamper with federal property, you could potentially be charged with a felony. The post office told me they would have to put my mail on hold for up to two weeks until they could replace the lock and keys. Seems risky to me to replace it yourself!

Wow, that’s crazy. Here at my place the post office told me to call a locksmith because they don’t have anything to do with the mailbox. I wonder if that’s just a lazy post office or???

Reminds me — when a friend bought a house recently, it came with no mailbox. We called the post office and they said we needed to go to Home Depot and buy a post and a mailbox and set it all up. Later, he calls me because he lost his key. Again, the post office said — not our problem so…. I used my handy tip above and we were in and out in 2 minutes (he didn’t own a drill or else I would have just told him to do it himself…).

Since the Post office is federal, I’m going to guess it’s all dependant on the local postmaster?

Are any lawers reading this? Input?

I just lost my mailbox key and called my property manager to find out how to replace it. She told me that the mailbox was “my own personal property” and that I should call a locksmith to replace the lock or find the maintenance manager of the building and he could do it for me. As I understand it, the MAIL is the only federal property. The box that it’s housed in isn’t. If you had a mailbox hanging on the side of your house and wanted to replace it, you could.

This is completely different if the mailbox is owned and maintained by the USPS. If that was the case, the mailbox would have an eagle on it.

Good points Manny. Thnx for the contribution.

It all depends on who “owns” the mailbox. Apartment “cluster” boxes are private property and must be maintained by the apartment, etc. Curbside “neighbohood” cluster boxes installed prior to 2003 are USPS property and are maintained by the USPS. Curbside neighbohood cluster boxes installed since 2003 are privately funded by the developer, and maintenance is the responsibility of the developer, HOA or residents.

From your photos it appears you have an older style “Neighborhood Distribution and Collection Box Unit” (NDCBU), which if memory serves were all installed prior to 2003. As such it is USPS property and unlawful to change the lock. The newer/current version is “Cluster Box Unit” (CBU), which are privately funded and maintained.

I suspect at this point it’s so convoluted that it’s difficult for even USPS employees to know if it’s lawful for you to change the lock of your mailbox. And much appears to be dependent on who you speak with at the post office – some postmasters are more lenient than others, some enforce the rules much more strictly.

any idea in how to get the main lock on a mail box repaired. I need a key from the postal service to unlock it. Thanks

Uh, only the USPS can do that. If the “main lock” were not working, the carrier could not deliver the mail at all. I highly suspect that isn’t the case here?

I just went to my post office in California and they told me I could replace my lock myself since the only way the mailman enters is from the back of the unit. I think that may be the difference between the ones prior to 2003. If the post office replaced it was $85 and I got one from locksmith for $17. You just need to know if opens clockwise or counterclockwise.

Perhaps your cluster box is owned by the post office itself? If so, they supply the keys and the rules. A homeowners assn. or apartment owner that owns the cluster box can have their own rules.

I live in CT. Can I do this on my own?

If you have a drill and a new lock — Yes.

However I can’t give you any legal advice. But that being said, if a locksmith is allowed to do it, not sure why a home owner can’t….

I’ve done a lot of searching over the past hour and honestly, it appears to be all across the map in regards to the legality of fixing your own mailbox. Some articles I’ve read say you can have the post office do it, others say you need to have your apartment complex or HOA take care of it and others say you can do it yourself or hire a licensed locksmith.

With these things in mind, my logic tells me if the HOE or Apartment ownership can fix a lock, then I the owner can fix it… Granted, I’m no attorney however after reading the article on USPS.com, I feel confident that it’s not illegal to fix my mailbox and maintain my mailbox as needed:

https://www.usps.com/manage/mailboxes.htm

If you review that web page, it has a section under Maintenance which includes things you should fix/replace as needed. With that in mind, my conscience is in the clear. :)

I hope this all helps anyone out there with this question.

It all depends on whether or not your mailbox is property of the post office (should have an eagle sticker or property sign). I had the same issue at my condo and they had me call a locksmith.

Awesome. And here I thought you were just a geeky Technology dude.

Some mailboxes are owned by the USPS, but I think most are not. So everyone should call their local postmaster and give them the address, they will tell you what to do – to either get a key through them or that you are on your own. Write down the name of the person who gave you permission to replace the lock, and be clear that you are going to replace the lock with a new one and not just re-key it.

Another safe idea besides calling the local postmaster is to just ask the USPS delivery person, they deliver mail around the same time every day all you have to do is be there when they come and ask them. Make sure you ask specifically if you can “replace the lock with a new one”.

I think that whoever tells you its okay to replace the lock on your own, write down their name in case someone does ask who gave you permission to do it. To avoid confusion, don’t drill out a lock at night and probably not right in front of the postal delivery person unless they were the one that told you to do it. Of course, always have a valid ID that matches the address in case someone were to stop you and ask you what you are doing.

I change these out weekly for my local Post Office. It costs $23 if it’s a new lock replacement (new resident). I do it for free if the customer has the old key and the lock doesn’t work anymore or the key has broken off in the lock. Some of the cluster boxes are owned by the Post Office and some by property owners. The Post Office is responsible to repair their cluster boxes and property owners are responsible for theirs. If a door is broken or bent and it’s ours. We’re required to fix it, if we don’t own it the property owner is required to fix it. Check with your local Post Office to find out who’s responsible for your cluster box. If the Post Office owns the cluster box, it’s a Federal Crime to mess with it.

I am a locksmith in here in Central California, we see these mailbox locks on an almost daily basis. Our rule of thumb is that of the group box is shiny and has a visible eagle logo on it, leave it alone. If it looks like it has been painted a few times but done maintenance guy you are good to go.

But I am not a lawyer just a locksmith that has had Police and the postmaster called on him.

I work in Fairfield County, CT. I had to replace mailbox keys for three clients. Each time, I was told by the U.S. post office to hire a locksmith as mailbox keys or mailbox were not their responsibility.

I figure if one follows the advice of the U.S. postal service, one can hardly be committing a crime. Unless, the mailbox in question is located at the post office.

The rate for a locksmith rates from $98 to $200. One locksmith gave me above advice if I wanted to save money. Price of new lock would be 17.00.

Pretty much the exact conversation I had with my local post office. ;)

I am renting a condo and we have mailboxes just like these. It took me over a month to get keys because the owners had moved into an assisted living facility and their family had no idea where they’d be. The post office said it was MY responsibility and they wouldn’t have access to it, nor would they have the key. My landlord/realtor hired a locksmith and I had a totally new lock switched out. This is VA.

Makes sense. In this case, you could have done the work yourself using the methods I documented on the article.

That said, if you have a landlord who is willing to spend the cash to fix it, even better! ;)

I lost the key to my mailbox which is only ours and in a gated subdivision. I took the day suggestion and tried drilling it out. I broke the drill bit off inside the key hole. What now???!!!

Most likely you have a tempered steel lock which is as tough as the drill bit. Did you notice that you were getting a lot of resistance?

If not, you may have had some sideways force on the drill bit. I assume you cannot get the bit out. If you can, I would.

You may be wise to call a locksmith. A locksmith may be able to pry the door open carefully or grind off the outer lock housing so the lock drops to the inside.

Yeah – probably best to listen to James on this one. If it were me…. I’d get medieval with it and use a larger drill and bit! :) :)

But that’s just me. hehehe

One thing you should make sure of is the metal used in your lock. Some post office locks are made of hardened steel as hard as your drill bit resulting in destroyed bits with little gain. Check first with a file on an edge to see if the metal is hard. Hardened steel will resist filing.

Also, make sure your lock is right. Some lock latches work 180 degrees off.

Great feedback James. Thank you for contributing to the article!

A couple sprays of WD40 did the trick!

Hiya De — Yeah, I always have a can of WD40 in my garage. Always amazed how handy it is!

One thing I don’t like about WD40 however is it really collects dust. At least in my house… That said, I always say, use what works for you!

This post will help my friend out. Thanks for the detailed instructions and photos.

You bet Daniel! Glad I could be of assistance! Honestly, it was sticker-shock when I call the locksmith. Amazed how much they try to charge for a 2 minute job.

Question: Do you have to drill it? Or is it possible to replace the lock without drilling?

By the way, when I called my post office to inquire about this, they said I had to do it myself or get a locksmith and then while I was asking my next question, the guy hung up on me! In the middle of my question! What a jerk!! And they wonder why people don’t use the post office anymore. Idiots.

The only reason to use the Drill is if you cannot get into the mailbox. If you can get into the mailbox, you can just uninstall the lock by taking off the bolt and clips (as shown in my photos).

Some mailboxes allow you get get in from both the front (your entry) and the back (mailman). So if you can’t get in from the front you could wait around for the mailman, explain the issues and perhaps he will open the back for you so you can uninstall the old lock and get the new one installed.

Hope that answers your question. Being that you’re having issues working with the local post office…. I’m going to guess the best path may be borrowing a drill from someone. :) :)

Thanks Steve! I actually can get into my mailbox still, with my key. It’s just that it sticks really bad and is hard to shove into the keyhole. So I thought it might be easier just to replace the lock. I spoke to a locksmith yesterday and he suggested trying to spray some WD40 first before replacing the lock. But he said that it should be an easy fix to replace the lock since I can still get into it with my key.

I’m so glad I found this blog. It’s really helpful information. Thanks!! :)

Thank you very much for the feedback! Glad my blog has been a help to you!

I have to replace my lock being the douche i rented a room to, took it upon himself to make a copy of that and others. The lock is easy enough to install, I just can’t find my lock. Home Depot, Walmart, OSH and Sears all no go. Tomorrow will try Harbor Freight, Lowes and Ace

Understood Jim…. Just one more reason to learn how to swap out a lock yourself — renters.

Being that locks are cheap, you might just try to grab a few and find one that fits the mailbox. It doesn’t need to be the same brand, just fit the locking hole on the mailbox. I’m sure you’re already going down that path but just in case — an FYI. ;)

You may want to let everyone know the US PS lock is not sold retail and there are no generic. Finding one that fits is not an option. The mailman will leave a note saying all mall stopped and sent to their family for p/u. I belive the most common lock .is the 1172C AKA C9200 and can be bought on Amazon for about $16. I got mine same day and all is good..

Great feedback Jim. Thank you. Article updated!

Thanks for the help! Pictures were very helpful.

BTW: Everyone who is saying don’t mess with your mailbox is misinformed.

I went to my local post office ( I recommend face-to-face vs calling), and they checked their list. Some mailboxes are “managed” by the PO, while others are not. If they manage it, they will replace it for you (after providing evidence of a lease or ownership), for a minimal fee ($25 for me).

If they don’t manage it, they will tell you to contact the HOA or apt. to see if they have an extra key. If not (as my USPS advised), they will suggest you get a lock and meet your carrier there and quickly replace it. My PO even told me to call the office in the AM, and ask the carrier to call me when he’s almost here so I can meet him. All is not lost. You CAN fix this.

Great comment Victoria. Sounds like you have a great PO in your area. Thnx for sharing your details. Which statue are you located?

Thank you so much. I followed your instruction and replaced my mailbox lock. I bought new lock from Dale and it is works perfect. you help me save a lot of money. Thank you again..

You are very welcome Johnny! Love the feedback! Another DIY success!

I used a rather hefty flathead screwdriver and simply slid it in the crack between the door and frame and gave it a quick pop. It took under 10 seconds and did no damage to the mailbox or the lock. Then I replaced the lock myself, pretty simple and paid under $10 at the hardware store for the replacement. By the way, it was my mailperson who suggested I do it, ha!

I saw the ‘Replace a Mailbox Lock in Under Five Minutes’ post just in time. I lost my key and called a Locksmith and the price they told me was $105 to come out and change the lock. I got hold of the mailman, took out my mailbox lock, went to ACE Hardware Store 3 blocks away, and bought a lock for $9.99 plus Tax with great help from the very knowledgeable sales person. The work for taking the lock out and putting it back was really just only fun 5 minutes doing it. Thanks you very much for the great $95 saver post.

That’s awesome! I’m happy my DIY article helped ya out! Thnx for sharing the story, Bernhard. Sounds like almost the same experience I had! hehehe

Anyway – Welcome to groovyPost! Hope to see you around the site.

I called my post office and they said they do not own our boxes in our development and to either call a locksmith or the hoa it’s a boatload to fix using a locksmith diy for sure!

So how did it go? DIY Worked I assume!?

I was about to replace my lock, but have been thinking, how will the post person deliver my mail. Do they have some kind of universal key for all new locks? I purchased a standard mail lock from HD.

Normally, there is a lock on the back (which the Postman uses) and one on the front (Which you use). The lock on the back opens the door for ALL the mailboxes in a cluster (normally). This lock should not be messed with.

Only change the lock YOU use to access the mailbox.

Bought a lock from HD for 6.50 and drilled away…under 5 minutes…great blog…thanks…

Fantastic! Yeah, I never realized how simple it was until I tried it. Almost think I should put an ad on Google for mailbox repair. :)

Thanks for sharing John! Appreciate the feedback.

I get my mail at the end of block where they put a group of mailboxes for block. Lost my key, I asked postmaster where to get replacement, he said the post offices didnt have one but woyld send someone out and replace the entire lock for only $50 (laughing). He suggessted I get my own lock and replace. I am getting ready to go do that now as well as get extra keys which can be kept in the part where postmaster opens it and if lost by myself or next tenant there’s spare keys. Washington state but post office is federal so I’m saying it’s legal. I don’t think he would of set me up for breaking the law.

So how did it go Sunny? Everything go well?

I live in a condominium .Till yesterday, the key for my mail box (the mailboxes are opened by carrier from usps with a common universal key)was gliding smoothly but today I could barely insert it half way through and it would not turn. I thought it was being obstructed by a thick journal or something. I called the mailman who who opened the universal lock, took out my mail. I tried again with the empty mailbox but still the same problem. What should I do? Can I have it opened again by the mail man and check the backside of the door if the lever or something is obstructing the key hole.

Please advise what should be the next step?

If it’s just “sticky”, I would try the Graphite powder I mentioned earlier. Hopefully this will loosen up the lock and allow you to not have to swap out the lock.

What about when the mailman accesses the boxes in my cluster from the front also? Does that mean I am going through two doors perhaps to drill out the lock? Curious because it’s 6 boxes in a vertical row and his main access is above in the center but his lock seems to be not fit to the front, sunken in to unlock the main door?

Well… I can’t say for sure without seeing what you’re talking about. I personally would not mess around with the lock the Mail Carrier users to deliver mail. If you do, you will need to provide a new lock and key for his lock.

Might be better to wait until they arrive, explain the issue and see if he can get you into the mailbox. You should be able to unscrew the lock from the inside that way. If you take a photo and post it here, I can see if I can help you.

So I was wondering: are they any potential barriers to getting the lock unlocked? I noted that one commenter suggested . But other than that, if I take your approach (I lost my key and nobody else has access to it), can I feel fairly confident that I’ll be able to turn the latch to unlock the mailbox? That is, is it possible that even after drilling, the lock latch wants to stay locked in place?

For most locks, once you drill through the lock the latch will just hang loose because nothing is holding it in place any longer.

You should be fine. The way I look at it — ANYTHING can be fixed. Especially something super simple like a mailbox lock.

Worse case, if you STILL can’t get it open, go to the USPS.com, put a hold on your mail at the post office and hire a professional if you’re not comfortable to FORCE it open. I guarantee the PRO will just bring a really big screwdriver and force it open then repair the lock.

But again, that’s worst case. You should be fine following the instructions I posted in the article.

Newer heavy duty CBU’s have hardened locks that can’t be drilled through with normal drill bits. I can tell when someone has tried to drill through one of these, because there’s gouges around the lock as the drill bit slid off the lock and onto the face of the mailbox.

Some of those locks are replacements. Some come with the CBU’s. The CBU’s with the outgoing mail slots that have been plasma cut out of the face of the 5/8″ steel face of the outgoing plate is pretty much guaranteed to have the hardened locks.

Thanks,man. Like you said, if I mess it up, it’s not like I destroyed the engine in a Porsche. I’m sure the locksmith can finish what I couldn’t, if I run into issues.

Bingo! That’s exactly my thinking.

Thanks, Steve. All went according to plan. DIY for the win!

key cannot unlocked. I use a minus screw driver to get tge internal threadmill aligned (out of alignment) then use key to unlock.

My lock stopped working and when I went to the post office they took my key and said they’d check it out. When I went back they said I had to pay them to change the lock. Since I didn’t have the money with me. I went back on another day and was told that I needed my lease, rental agreement or deed to prove I lived there before they could change it. I can’t believe my state drivers license wasn’t enough. I put my mail on hold via their website and I’m going to change the lock myself. The USPS is a waste of time, money, and energy to deal with. I’m probaby going to go paperless with my bills now.

I’m hoping you can help with an issue related to these locks. One of my mail deliverers likes to shove the mail all the way to the front of the mailbox (I assume to make it easier for us to grab), which sometimes blocks the bar on the back of the locking mechanism from being able to open. Do you have any recommendations on a cover or something I can put over it so that this will stop happening?

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