Installing a new metal mailbox may sound like a mundane chore, but did you know that you had to consider some guidelines before replacing your old one? According to home repair expert Danny Lipford, one has to contact their local post office to get approval for their mailbox’s kind and location before setting it up. “The first rule when adding a new mailbox is that your mail carrier has open access to the mail holder at all times.” 

He says that approved mailboxes have “US MAIL” and “APPROVED BY THE POSTMASTER GENERAL” on the front of its door. In this article, you’ll find an overview of USPS mailbox standards for curbside, door slot, and wall-mounted mailboxes that fit the local guidelines.

Mailbox Size and Construction Standards for Curbside Mailboxes

  1. Custom-built Mailboxes: If you plan to build a new metal mailbox, contact the USPS Engineering Office to get the measurements they approve. Want your mailbox to hold larger packages? Ask about Next Generation Mailboxes, as they have different guidelines.
  1. Mailbox height and location: The proper location for curbside mailboxes is 6” to 8” back from the curb and is 41” to 45” above the road surface. Measure up from the ground to the point of mail entry to see how high it is. If you live in a location with no raised curb, contact your local post office for guidance.
  1. Numbers and attached home address: Attach your house or apartment number to your mail holder using adhesive numbers, which are available at hardware stores and home improvement centers. In the case of your home being on a different street from where your mailbox is, add your full address to the mailbox to avoid confusion and missed mail.
  1. Mailbox post requirements: Curbside mailboxes must have a 4-inch by 4-inch wooden post or a 2-inch thick aluminum or steel pipe for support, as per Federal Highway Administration standards. Materials that offer strong support but are still bendable/breakable in case of damage are recommended, so steer clear of heavy metal, brick, or iron supports.
  1. Newspaper delivery boxes: Since federal law prohibits the placement of non-postal items in mailboxes, USPS says that you can add a receptacle for newspapers and the like to the post of your curbside mailbox! The receptacle must meet these standards: 
  • It doesn’t touch the mailbox itself for any support.
  • The newspaper receptacle doesn’t interfere with mail delivery/block the mailbox flag/present any hazard to the mail carrier.
  • It doesn’t extend past the front of the actual mailbox when closed.
  • It does not display any type of advertising unless it is the name of the publication.

Mailbox Maintenance

As it is with everything else on their property, homeowners are responsible for maintaining and repairing their mailboxes. As such, it’s best to check your mailbox yearly! 

Has it become difficult to open and close? Does it look worn? If you’re unsure, then here are some things to remember when you do your mailbox check:

  • Check for loose hinges on the door or slot.
  • If some parts have rusted or come loose, purchase new ones from a hardware store.
  • Clean up stains with products like Wet & Forget Outdoor.
  • Replace house numbers and/or letters that have faded or loosened.
  • Keep the path by your mailbox clean. Make sure nothing blocks it from view, like shrubs or outdoor decor.
  • Contact your local post office before moving or replacing your mailbox entirely.
  • Bonus: Add reflective numbers and letters to your mailbox so that it’s easy to spot in case of emergencies!


Mailboxes serve a functional purpose, but there’s no reason for them to remain as the drab metal boxes that we leave in front of the house. As long as they fit USPS mailbox standards, your metal mailbox can be as unique and striking as you want it to be. 

Are you looking to upgrade your old traditional mailbox to a modern mailbox? Modern Aspect makes minimalist address plaques, custom address signs, and metal mailboxes for the modern homeowner. Browse our shop and say goodby to bland decor today!