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Frequently Asked Mailbox and Mailroom Supply Questions

How many cartons is the cluster box unit shipped in?

Regardless of model ordered (8, 12, 13, 16-door, etc.), you will receive two cartons per cluster box unit ordered. One box will contain the pedestal (approx. 25lbs), and the other, larger carton will contain the mailbox module (depending on the unit ordered, approx. 100-150 lbs.). If ordering our “decorative” cluster box units, you will receive additional cartons that will contain the decorative roof cap and/or pedestal cover.

Please count the number of cartons that you receive, make sure that your count corresponds with the number of mailboxes that you ordered AND the carton count on the delivery receipt that the freight company provides. Also, upon receiving the goods, please make a visual inspection of the cartons being received, and note ON THE DELIVERY RECEIPT provided by the freight driver any damage that you observe. Ideally, your count and inspection of the shipment should be made with the truck driver still present.

My cluster box shipment arrived, and one of the boxes appears to be damaged - what should I do?

If the freight driver has not yet departed, please make proper notations of the damage on the delivery receipt prior to signing for the goods. If the damage is significant enough that it is unacceptable to you, you may also refuse delivery of the damaged product. You should only refuse delivery of the damaged item and not the entire shipment. Please report this issue to us as soon as possible thereafter.

If the damage is concealed and was only discovered after the truck driver has left, please report it to U.S. Mail Supply’s customer service center at 1-800-571-0147 as soon as possible. Typically, most freight companies require that any shortages and/or freight damage be reported within 7 days, so it is important to thoroughly count and inspect your shipment immediately upon delivery, or as soon as possible thereafter. IT IS ALSO IMPORTANT TO PROMPTLY REPORT ALL SHORTAGES AND FREIGHT DAMAGE WITHIN 7 DAYS SO THAT THE APPROPRIATE CREDIT CAN BE OBTAINED FROM THE FACTORY AND/OR FREIGHT COMPANY. This will also allow us to quickly process a replacement order for you, if necessary.

Quite often digital photographs of the damage can be very helpful in illustrating to the factory and freight company the specifics of the damage.

We do our best to quickly address shortage and freight damage issues for our customers, but failure to promptly report shortages or freight damage within 7 days makes it much more difficult, and sometimes impossible, for us to resolve these issues without the customer incurring additional expense.

Is everything that I need included when I purchase a cluster box unit from U.S. Mail Supply?

Everything is included with a cluster box unit purchased from U.S. Mail Supply, except for two items:

(1)    USPS “Arrow” Locks – For security reasons the USPS does not allow the factory, or any non-USPS personnel to possess the master locks (also known as “Arrow Locks”), which are installed in the outgoing mailbox door, as well as each of the parcel locker doors. The local USPS will install this lock on these doors upon your request to do so. They typically do not charge for this service.

(2)    Anchor Bolts for Mounting the Unit – The USPS has requested that we do not include the anchor bolts for mounting the unit to concrete due to varying frost lines throughout the United States. The factory recommends ½-inch diameter J-Bolts, with the length to be determined by the thickness of the concrete pad that is poured (most common pad depth is 5-6 inches). You will need four anchor bolts per unit, and they can be picked up at any local hardware store for a couple of dollars each. Please refer to the installation instructions that are shipped with the mailbox or view, print or download those instructions now.

I just received my cluster box unit and I cannot find the tenant keys, mounting hardware or installation instructions…what should I do?

All of the keys, mounting hardware, and installation instructions ship inside the mailbox cabinet. Once you have the mailbox module out of the carton and on a workbench, open up the outgoing mailbox door which will not have a lock on it (directly below the outgoing mail slot on the right-hand side) (the local USPS installs this lock – see above),  and push up on the latch located on the left side of the interior of this compartment. BE CAREFUL. THE UNIT IS FRONT HEAVY. This will release the right side of the cabinet like a French door. Subsequently, the left side of the cabinet can be opened by releasing the latch. All of the keys, mounting hardware and installation instructions will be appropriately marked in the lower left hand compartment.

Are all of the mailbox locks included and installed in the cluster box unit when I receive it?

Yes. You will receive 3 keys for each tenant mailbox lock. It is recommended to retain at least one key for each mailbox as a spare.

Is it possible to get additional keys for the mailboxes when you buy a new cluster box unit?

Yes, but you will need to purchase key blanks and then have copies made locally. The manufacturer offers a maximum of 3 cut keys per mailbox. For security reasons, and by order of the USPS, you cannot buy cut keys after the original purchase of your mailbox.

What if I need more keys to my mailboxes after I have bought the cluster box unit?

You would then need to purchase a key “blank”, which can be taken to any locksmith or hardware store that cuts keys, along with an original cut key that they can then copy for you.

The locks and key blanks used for cluster box units are proprietary, and usually cannot be found in a hardware store or at a locksmith, so you will need to contact us at 800-571-0147 to order them.

Please note that there are two different key blanks used by the manufacturer. So you will need to provide us with the key code number off of the original keys. This code number will be four digits followed by the letters “PS”. One key blank is used for key code ranges 1000PS thru 1999PS and 3000PS thru 3999PS; and another, different key blank is used for key code ranges 2000PS thru 2999PS and 4000PS thru 4999PS.

Usually the factory will try to stay within the same key code range for all of the mailboxes in a cluster box unit order, but it is not always possible for larger order. So you will want to check to be sure prior to calling us to order key blanks.  

Can I order more locks for the tenant doors on my cluster box unit?

Yes. You may order replacement locks at any time, which will include 3 keys. Typically the only reason you would want to replace a tenant mailbox lock is when a tenant moves out, or if all of the keys for a lock are lost.

Should I contact the local USPS before I install my cluster box unit?

Yes. We always recommend speaking with your local postal officials prior to installing your cluster box unit. The USPS does have the authority to dictate the installation placement of your cluster box unit, however most USPS officials are accommodating.

What is a parcel locker and how does it work?

A parcel locker is for package delivery only. If a tenant receives a package on a particular day, the USPS mail carrier will put a key in the tenant’s mailbox and the key tag will instruct the tenant to take the corresponding key, insert it into the top lock of the corresponding package locker, unlock and open the door. The tenant removes their package from the parcel locker and closes the door. The key WILL REMAIN IN THE LOCK, AND CANNOT BE REMOVED. This lock is referred to as a “captive lock”. The only party who can remove the key from the parcel locker’s captive lock is the USPS mail carrier. The next time the mail carrier services that mailbox he will disengage the key so that the parcel locker may be used the next time a tenant has a package.

Because of how a parcel locker works, it CANNOT be used as a regular tenant mailbox. By USPS regulations, cluster box unit parcel lockers cannot be removed, changed into mailboxes, moved or otherwise modified from the original purpose.

Can I change the configuration of the F-Series cluster box unit mailboxes?

No. The F-Series Cluster Box Unit mailboxes were designed by the USPS. The USPS owns the patent on these mailboxes and does not allow ANY modifications to them whatsoever, including eliminating, re-sizing, moving or adding mailboxes, parcel lockers or outgoing mail compartments.

Can I mount a cluster box unit on a wall instead of on a pedestal?

No. A Cluster Box Unit is not manufactured to be mounted on a wall, and requires either a pedestal or some other supporting structure beneath it.

Can I mount a cluster box unit on a pedestal from my old mailbox, or on some other style of pedestal besides the pedestal that is sold with it?

It is NOT recommended to install a Cluster Box Unit on an old, formerly used pedestal, whether it is from a cluster box unit or some other style of mailbox. The pedestal that is sold with our cluster box units is specifically designed for that purpose. An old, used pedestal is most likely not strong enough and may have corrosion, etc., that could lead to a collapse of the mailbox, which is a danger to both tenants and the mail carrier.

A cluster box unit must be installed at the precise height as dictated by the USPS. If you wish to use any mounting method other than the factory supplied pedestal it is strongly recommended that you obtain prior approval from your local Postmaster. We do not take returns of mailboxes resulting from communication issues between the customer and the local Post Office.


I currently have the older style rear-loading Neighborhood Delivery & Collection Box Unit (NDCBU) and just want to replace it. Why can’t I just buy another one?

Why do you still sell NDCBU’s if they are no longer USPS approved? What is the difference between the older style NDCBU and the new style CBU?

The USPS de-certified the older style NDCBU’s back in 1999 when they went to the new front-loading cluster box unit specification.

In isolated cases local postmasters will still allow their customers to use the older style NDCBU’s, particularly if they are replacing an existing unit that was damaged or is otherwise no longer functional. This is typical when multiple NDCBU’s are side-by-side, and one of them requires replacing.

There are also many private applications (non-postal) for NDCBU’s. One example is that trucking companies use them for their drivers to pick-up or drop off keys and paperwork. It is for these reasons that NDCBU’s are still being sold.

The newer style cluster box units are considerably different from the old NDCBU’s. This includes having a much thicker aluminum cabinet and doors; manufactured with much tighter tolerances, which means it is much more difficult to pry open doors; more weather resistance; stronger door locks; re-enforced postal control compartments; re-configured tenant compartments that more easily accommodate larger mail, such as magazines and catalogs; and the inclusion of secured outgoing mail compartments and parcel lockers for oversized packages. Obviously, mail carrier access is now from the front of the mailbox, as opposed to the back on the older style NDCBU’s as well. There are no USPS Approved rear-loading outdoor pedestal style gang mailboxes any longer. Shop our inventory of USPS approved cluster mailboxes.

The bottom-line is that if you wish to purchase the older style Neighborhood Delivery & Collection Box Unit, you must obtain local Postmaster approval prior to ordering. We do not take returns on NDCBU’s under any circumstances.

Shopping for mailboxes, mailroom accessories and supplies can be difficult. It is hard to know which options are right for you and your situation. U.S. Mail Supply not only has an extensive range of products, we also have plenty of information to help you make the best selection. Here we have compiled some of the most frequently asked questions by our customers, and there will be more to come. If you don’t find the answers you are looking for here, call us! We have a very knowledgeable and helpful staff available to help you out.

Contact U.S. Mail Supply by calling 262.782.6510 or 800.571.0147 for more information.
Make sure to choose the RIGHT mailbox.

Don't worry, we can help you figure out what's best and most cost efficient for your space. A representative at U.S. Mail Supply will help you figure out what is required for USPS or private delivery, the number of units you need and any information required for installation.