Locking Mailboxes 101

What you should know about locking mailboxes, and how they work

Many people ask us if their postal carrier will need a key if they buy a locking mailbox. The answer is no. In fact, letter carriers are not allowed to carry a key for residential mailboxes.

Most USPS approved residential curbside locking mailboxes work in the same basic way as an unlocked curbside mailbox. The postal officer deposits your mail through an incoming mail door or slot. This door is not locked, and is usually big enough to accept all your mail and small parcels, but should not be large enough to allow a fishing hand to reach in. (See for example this article).

locking-mailboxOnce your mail is in a secure locking mailbox, the incoming mail is protected from would-be mail and identity thieves. For true mail security, the incoming mail slot should be too small for prying hands to reach in and fish out your mail. For larger, commercial size boxes, the mailbox must be designed to prevent reaching through the incoming mail slot. Additionally, a secure locking mailbox should feature an anti-pry mechanism such as the Mail Boss anti-pry latch to prevent leveraged entry. Otherwise, the mailbox can be easily pried open in seconds with a screwdriver or other household items.

With a locking mailbox, the homeowner removes their mail with a key by unlocking the mail-removal door and retrieving their mail. Depending on the model and style of the mailbox, the key-locked door may be in the front, rear, or both.

While a well-built locking mailbox like the MailBoss security locking mailbox can provide security for your incoming mail, no USPS approved locking mailbox protects your outgoing mail. Generally, outgoing mail is handled by placing it in a separate compartment near the incoming mail door. The mail may be held by a clip or sit inside the door (credit jerome). Since the outgoing mail must be available to the letter carrier, the door is not locked.

Red flags are used to signal to the postman that there is outgoing mail, but these red flags also signal to mail thieves that there is a wealth of material ripe for the plucking. Thieves target “flagged” mailboxes because they often include bill payments with account information and checks which they can wash and reuse fraudulently. For this reason, we recommend depositing your outgoing mail in a USPS blue box or other secure location.


  1. Jerome Cherry on July 16, 2017 at 2:12 pm

    Who is the guy named Jerome mentioned in the article?

    • John J on March 23, 2021 at 10:25 am

      He seems pretty legit.

  2. Kevin Murphy on October 10, 2017 at 10:35 pm

    I live in an area serviced by mail couriers who delivery in their little trucks.
    Since installing locking mailbox the driver will no longer deliver to our front porch any package that would otherwise have fit in a non-locking mailbox. They simply put a slip in the box telling me I can pick it up at post office tomorrow. Driveway is short.
    Is there a specific regulation covering packages and locking mailboxes?

    • Larry on March 15, 2021 at 7:30 pm

      This is your deliver man or woman. They are to lazy to bring to your door.

      • Elly on May 18, 2022 at 4:42 pm

        Sorry Larry, but you are very wrong. I am a mail carrier and the way may boss explained it to me was “what if everyone got locked boxes, you’d be out there all night trying to deliver every little package to the door. Plus you don’t get paid for that.” We are under so much more pressure than people realize, please try to be more understanding instead of just calling us lazy. I assure you I am not, I love my customers but there’s only so much I can do.

    • Dawn Rogers on August 13, 2021 at 6:38 am

      The notice is supposed to give a choice of asking for redelivery or p/up at post office
      .I would look into adding a neighbor’s address for package drop off, who is able to hold it for you.

    • Jessica on November 2, 2022 at 10:12 am

      Yes there is a regulation for this. If a customer puts a locked box up that means they feel like there may be issues with theft in their neighborhood. So we are not to deliver anything to your front porch, Large or small. If you need to keep your mail under lock and key that same rule applies to your package mail. Think about the packaging your bank checks come in when you reorder. They used to come in a box. So you lock your mail box but want a carrier to leave a box of personal check from your bank on the front porch.?

  3. oussama touzni on October 28, 2017 at 2:19 pm

    identity theft is becoming a major problem in the usa

  4. TP on November 4, 2017 at 8:18 am

    I don’t see outgoing mail as a problem. Given the advent of online banking, who still pays bills through the mail? I’d use the online banking just to save the (now quite expensive) stamp, but online banking is more secure and makes it easy to maintain records of bills you’ve paid.

    I am concerned about the delivery of small packages. I wish a better option existed.

    • Del Fredricks on August 23, 2019 at 2:31 am

      A bit more than paying bills. Also, receiving delivers of your On-line purchases. Think inside the box here.

    • Red on November 7, 2019 at 11:06 pm

      We recently installed a Mail Boss locking mailbox for our single family residence. I kept putting outgoing mail inside the main chamber, putting up the red flag, and the mail deliverer would not take our outgoing mail! I wrote a note asking the deliverer to please take the outgoing mail and stuck it to the mailbox. They wrote back on my note saying (1) they don’t have access to the main chamber, and (2) outgoing mail is supposed to be placed under the clip on the lid of tiny upper outgoing slot. First, the mailman not having access to our locked mailbox was news to me! I’ve never heard of that before. The neighborhoods I’ve lived in previously had ONE locking box for like 10-12 houses. The mail deliverer had a key to that! Same goes for apartment complexes. Secondly, that slot where outgoing mail is supposed to be clipped to IS TOO SMALL for anything more than one or two plain letters. So the time-sensitive stack of papers I put in outgoing mail didn’t get picked up, and I didn’t know why until the mail person responded to my note! And now small packages we’re waiting for surely won’t be delivered; USPS never comes up our driveway to the house for any reason. (Though UPS will!) There are two disabled residents in our household (one being me); both don’t drive and have mobility issues. There are no big blue mailboxes within a 5 mile radius of our house. So now just getting a slightly larger than normal letter mailed has become a problem… nearly impossible if there’s not an able-bodied person around to run to a post office or mailbox. I don’t recall any of that info about outgoing mail in the literature or instructions for installing the locking mailbox. If I’d known this would be such a ordeal, I would NEVER have installed it. We’re now considering going back to a non-secure mailbox. The potential problem of mail theft is now far less of a concern than simply getting an important letter mailed in a timely manner. This info about outgoing mail should be FRONT AND CENTER of the install directions. That would have saved us a lot of time & hassle.

      • Elaine Weirich on November 11, 2020 at 7:45 am

        My carrier recently informed me that a household with a member with a disability can apply with USPS to have their mailbox by the front door instead of along the street. I have no idea how long that application/approval process would take, but if I were you I’d check into it.

        • Elly on May 18, 2022 at 5:29 pm

          That’s true but there’s certain criteria like the person has to live alone, cannot drive and needs a drs note. It’s called a hardship.

  5. Heather on January 5, 2018 at 1:08 pm

    How is it that the PO is not able to pick up from a locked mailbox, yet they can from locked boxes at an apartment complex??

    • John Richardson on April 8, 2020 at 7:04 am

      Postal carriers that work apartment complexes have a standard key as those apartment boxes are designed with a single lock for the carrier to open all the boxes at once to case the mail and then close the box up. Individual locked mailboxes at residential homes do not have the standard lock – therefore if a carrier were to have a key to yours he would have to have a key to all the other residences on his route. I mean if you think USPS is slow now just imagine how slow it would be if the carrier had to sort through 300 keys every time he came to a locked box.

      • Fabiola on April 13, 2021 at 7:49 am

        John. John. Seemed obvious to me. Every time I read a comment complaining about postal workers not being able to open the locked single box, I shook my head.

    • Edward Owen on January 11, 2021 at 8:01 am

      Apartments use gang style mailboxes to which mail carriers have keys. They open the entire front or back of the gang of boxes at once. Residential mailboxes are all keyed differently and mailcarriers are not allowed to have these keys. It would be impossible for them to do so unless they were on a masterkey.

    • Elly on May 18, 2022 at 5:31 pm

      I pick up outgoing mail from locked boxes quite often so I’m not sure why others wouldn’t.

  6. Gabriel on May 29, 2018 at 11:34 am

    Hi Claudia, thanks for your comment. Personally, our mail carrier does this too. I am happy to hear this and think that a lot of individuals are more than willing to go the extra mile (quite literally) to make someone happy and perform their job the best that they can. We surely strive here at Mail Boss to design boxes with you in mind, and ensure that your security, time and money are all valued.

  7. A Smith on July 13, 2018 at 7:02 am

    I just bought a house with a secure residential mailbox (not post office box). I do not have the key. What can I do?

  8. Gabriel on July 13, 2018 at 11:07 am

    Hi A Smith, thanks for your inquiry. If you have a Mail Boss mail box, then we will be able to assist you if you call into our customer service at 1(800)589-7990. The lock would need to be drilled out and replaced. Otherwise, I would recommend contacting the manufacturer of the mailbox. Thanks!

    • Cris on December 5, 2020 at 11:03 am

      How can you tell who the manufacturer is? I locked myself out of my mailbox and need to order a new key, but I don’t know who the manufacturer is. I have found RSK 11/02 stamped on the lower bottom plate but that’s it. The Key and lock have B 30 stamped on them. Any help is greatly appreciated.

      • Gabriel w/ MailBoss on December 15, 2020 at 12:29 pm

        Hi Cris – That definitely isn’t one of our boxes by the description you gave… What does the key look like, is it cut on both sides?
        It’s likely another mailbox manufacturer’s lock system… you should be able to find a comparable lock to what you already have there at your local hardware store!

  9. Bryan on June 23, 2019 at 1:51 pm

    Wish they were like TSA which the mailman would carry a universal key to open mailbox with out going mail

    • John Richardson on April 8, 2020 at 7:06 am

      The postal carrier only has a so called universal key that works in mobile home parks or apartment complexes that have a lock box mail system. It is a common lock and key systems that was established many years ago. Letter carriers then can open the whole lock box system and case mail and then close it up. Then individual residences can access their mail.

      • Cr on November 18, 2020 at 12:31 pm

        For years I provided a padlock to lock my box as a neighbor was stealing my mail on a daily basis. The letter carrier was locking after placing mail in box. Now apparently this letter carrier decided he does not want to do anymore and post office told me to get a PO approved locking box. Have homeowners guidelines and there are no approved boxes both size and style. What can i do?

        • Gabriel w/ MailBoss on November 20, 2020 at 11:26 am

          Hi Cr, thanks for your inquiry! I am surprised your mail carrier took the time to replace and lock a padlock each time they delivered your mail!

          I would recommend reaching out to your HOA. We offer bulk discounts to HOA’s, and all of our curbside boxes are USPS approved (and available in a variety of colors).

          Good luck!

    • Randy on January 19, 2021 at 12:00 pm

      Well, then they would become ubiquitous and thieves could order the key. Incedentally, most locks can be easily opened. An alarm that tells you when your mailbox is opened might help. At least you would know when your mail is delivered and you can retrieve it without delay.

  10. Gabriel on July 9, 2019 at 12:54 pm

    Hi Bryan, we have seen locks mounted onto our boxes before in which the mail carrier has a key. I would recommend contacting your local post office or post master to inquire about such a lock. Luckily, our locking package mailboxes do take quite a large incoming mail bundle or package, allowing the owner both security and ease of use.

  11. Susan on November 30, 2019 at 3:08 am

    I do not understand how the mail person can get outgoing mail out of the box.

    Is the box always locked?

    • Gabriel w/ MailBoss on December 6, 2019 at 8:29 pm

      Hi Susan, thanks for your inquiry! On all of OUR curbside models, there is a way to retrieve outgoing mail via the top, unlocked door. On the mail manager, that is a small clip attached to the back of the door. On the Mail Boss and Package Master models, there are larger dedicated areas for outgoing mail located behind the top, unlocked door as well. Your mail carrier will not carry your key, nor have access to the locked section of your box. Only you will be able to retrieve your incoming mail from the secure, locked section of the box. Hope that clears things up! Let us know if you have any more questions.

  12. Joe A on January 4, 2020 at 2:18 am

    Why is it that all my Cox Cable and Direct TV flyers are stay safe in my unlocked mailbox? I’m going to save the envelopes and instruct SS and my bank to send me money in their envelopes.

  13. Erin B on January 27, 2020 at 2:48 pm

    What’s the likelihood of another mailbox key fitting my locked mailbox?

    • Gabriel w/ MailBoss on January 28, 2020 at 2:15 pm

      Hi Erin, thanks for your inquiry. On a MailBoss curbside or wall-mount mailbox, we have over 1500 unique key and lock combinations. The chances of another MailBoss key fitting your lock are roughly 0.00067%!

  14. Karen Goodwin on February 16, 2020 at 9:40 am

    Since I had a check I was sending out was stolen I am looking to make my life simpler. They tried to open up credit cards, printed new checks and caused a lot of grief. How safe is an outgoing letter in these boxes? This was a nightmare I don’t care to experience again.

    • Gabriel w/ MailBoss on February 18, 2020 at 3:01 pm

      Hi Karen, we recommend dropping off important/confidential outgoing mail DIRECTLY at the post office. OUTGOING mail is never fully secure in a curbside locking mailbox.

  15. Karen G on February 16, 2020 at 9:41 am

    Since I had a check I was sending out was stolen I am looking to make my life simpler. They tried to open up credit cards, printed new checks and caused a lot of grief. How safe is an outgoing letter in these boxes? This was a nightmare I don’t care to experience again.

    • Gabriel w/ MailBoss on February 17, 2020 at 5:10 pm

      Hi Karen, sorry to hear that happened to you! Whenever your sending out checks, you need to make sure it is deposited in a secure drop off box, or dropped off directly at the post office. Unfortunately, locking curbside boxes do not feature a locked outgoing mail area, so outgoing mail is NEVER secure. Good luck!

  16. Carina on July 15, 2020 at 7:51 am

    I bought a mailbox with a lock and it got me thinking how will my mailman take my letters out. I live in a residential home and I’m wondering if I’m suppose to give the mailman a key?

  17. Syahin Hussein Ali on September 25, 2020 at 10:11 pm

    I just bought a house with a non secure residential mailbox (not post office box). Any tips and suggestions on how can I secure my mailbox?

  18. Trudy Moore on January 22, 2021 at 5:13 pm

    Hello. We are interested in having new HOA mailboxes for our ten units in northern California. They would be outside on a secure stand. What would the cost be? Do you separately hire someone to do the work or do you both sell the mailboxes, the stand and do the work?

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