row of mailboxes at different heights

A mailbox is an integral part of your home to enable you to receive all correspondence to your street address. When replacing your old one or installing a mailbox for the first time, it’s important to know how high from the ground to place it. 

The United States Postal Service (USPS) has certain regulations when it comes to mailbox height. This is so that it’s easy for mail carriers to deliver mail into your mailbox. 

Below, we take a look at how high a mail should be according to the USPS. We’ll also cover the rules for mailbox placement so that you know how to properly position and mount your own mailbox to avoid any penalties. 

USPS Regulations: How High Should A Mailbox Be?

The position of a mailbox depends on two factors: the height of the mailbox, and the curb placement of the mailbox post. Follow these regulations to prevent unwanted fines and to make life a lot easier for your letter carrier. 

Mailbox Height

The mailbox height is often overlooked as an irrelevant detail. However, it actually needs to be at a certain position and height according to USPS mailbox regulations. 

A mailbox should be at a height between 41 and 45 inches. This is the height at which your mailbox should sit measured from the road, rather than the ground of your property, (which will generally be higher). From the ground, the measurement should be up to the very bottom of the mailbox door. 

This is the height requirement because it is ideally positioned for when the mail delivery person sets the mail into the mailbox from their vehicle. As such, installing mailboxes at this height makes for a quick and efficient postal service delivery system. 

Avoid burying a curbside mailbox more than 24 inches into the ground. The wood for the post must be smaller than 4” wide and 4” high. 

Using concrete is a good way to keep a mailbox sturdy in the ground as it creates a solid foundation for the mailbox. This way, it shouldn’t move or break easily. 

Mailbox Curb Placement

In addition to the height requirement for a mail box, the position on a curb is just as crucial and you need to adhere to the USPS’s regulations. 

The mailbox post should be between 6” and 8” from the curb, or the edge of the street or road if there is no curb. This measurement should be from the front mailbox door. Again, this placement allows easy access for mail carriers to drive by and deliver mail into the mailbox without needing to get out of their vehicle. 

All residential roadside mailboxes should be on the right side of the road so that the mail carrier vehicle can reach them while still staying within the correct lane while driving. 

It is also good practice to keep any obstructions away from the curbside mailbox, such as trash cans or vehicles, so that it does not block access for the mail carriers which creates a delay in their mail delivery operations. 

If there are any uncertainties around the position of a mailbox, and the other rules and regulations, it is always best to contact your local postmaster at the Post Office. Postal service regulations might differ from area to area. 

mailbox at correct height for postman in vehicle

How High Should A Wall Mounted Mailbox Be Placed? 

A wall-mounted mailbox is a convenient way to position a mailbox that keeps it sturdy and reduces the risk of it getting damaged or knocked over. This is also ideal for those who do not have much of a garden or outside space, as it can attach to the house itself if necessary. 

Wall-mounted mailboxes will follow the same regulations as others, such as a mailbox post: 41-45” above ground and 6-8” away from the curb, to create easy access for mail carriers either driving past or walking to the mailbox. 

How High Should A Door Slot Be?

A door slot is a good alternative to a mailbox, to receive mail straight into the house. If you opt for this, there are specific rules and regulations to follow. 

The opening of the slot must be no smaller than 1.5”x7”. The slot must be 30” above the floor, measured from the bottom of the slot.

If it is a vertical slot, the hinge must be on the opposite side from the actual door hinge. For a horizontal slot, the hinge must be at the top of the slot. 

Important USPS Rules For Installing Mailbox Posts & Mailboxes

The Post

A rural mailbox post should ideally be a 2’ diameter aluminum or steel pipe, or a  4” x 4” wooden structure, according to the Federal Highway Administration regulations. These are the best mailbox supports as they are sturdy enough to support the mailbox, but will bend or collapse with the pressure of a vehicle. 

The post must be buried no deeper than 24” into the ground. The Federal Highway Administration recommends this depth as it means the post would come loose should a vehicle hit it, causing little damage. 

When installing your mailbox post, avoid using supports such as concrete posts, farm equipment, milk cans filled with concrete, and heavy metal pipes. These types of mailbox supports are more unyielding and could be dangerous. 


Over time, the mailbox will need care to keep it in good working condition. Every six months or so, it is good practice to tighten the door hinges. You should keep an eye on it to replace any old, rusty parts or faded/missing house numbers. 


A mailbox should clearly display just your house number. This makes it easier for the mail carrier to get the right mail to the right house. 

If the mailbox is not located on the same street as the house, then you need to clearly display your full street address on the mailbox. 

mailbox standing open with mail inside


Positioning a rural mailbox in the right way is incredibly important. You must follow USPS height guidelines to ensure your mailbox is easily accessible so that you get your mail without any issues. 

With any uncertainties about mailbox rules and regulations, it is always best to contact your local postmaster for guidance and advice. 


******It is always recommended to contact your local postmaster prior to installation. While most of our mailboxes are USPS-approved your local postmaster may have specific preferences in terms of mailbox types and installation location******

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