Yes, you can have more than one mailbox — but the rules depend on your property type. Single-family homes are generally limited to one curbside mailbox per address under USPS regulations. Multi-unit buildings, businesses, and separate addresses each have their own allowances.
Here's a clear breakdown of every scenario so you know exactly what applies to your situation.
The USPS Rule on Multiple Mailboxes
USPS Publication 17 — the official residential mail guide — states that each deliverable address is entitled to one mailbox. The key word is address, not property. If you have one address, you get one curbside mailbox. If you have multiple distinct addresses, each one can have its own.
This is why the question "can I have two mailboxes at the same address?" has a different answer than "can I have mailboxes at two different properties?" — they're governed by different rules.
📬 Key rule : USPS delivers to addresses, not to individuals. One address = one authorized curbside delivery point. Additional mailboxes at the same address require a separate unit designation or a USPS-approved exception. See the full policy in USPS Publication 17.
When You Can Have More Than One Mailbox
Single-family home with a secondary unit If your home has a basement apartment, in-law suite, or garage apartment with its own separate address (e.g., 123 Main St and 123A Main St), each unit is entitled to its own mailbox. The unit designation must be registered with USPS and reflected on official mail.
Multi-unit residential buildings Apartment buildings, condos, and duplexes require individual mailboxes for each unit — this is a USPS mandate, not an option. Each unit must have a clearly labeled, accessible mailbox. Cluster Box Units (CBUs) are the standard solution for buildings with 3 or more units.
Multiple separate properties If you own a rental property, vacation home, or second residence at a different address, each property gets its own mailbox. These are treated as independent delivery points — no special permission needed.
Businesses Commercial addresses can have multiple mailboxes to separate departments, PO Box mail from street delivery, or handle large package volumes. As long as each box is properly labeled and accessible to the carrier, USPS allows it.
PO Boxes in addition to a home mailbox You can rent one or multiple PO Boxes from your local post office on top of your existing home mailbox. PO Boxes are separate from your residential delivery and don't count as a second mailbox at the same address. They're especially useful for receiving sensitive documents, business mail, or packages securely.
⚠️ What you cannot do Install a second curbside mailbox at the exact same address as your existing one without a separate unit designation. USPS carriers follow address-based delivery routes — a second unlabeled box at the same address will be ignored or cause delivery confusion.
The One Scenario Most People Miss
The most common reason homeowners want a second mailbox is a home-based business — they want to keep business mail separate from personal mail at the same address.
USPS allows this, but not with a second physical curbside mailbox. The correct solutions are :
Option 1 — PO Box rental Rent a PO Box at your local post office from $10-30/month. All business mail goes there, personal mail comes to your home. Clean separation, no address confusion.
Option 2 — Suite designation Register a suite number with USPS (e.g., 123 Main St, Suite B) for business mail. This creates a second deliverable designation at the same address. Your carrier can then sort accordingly — but you'll still likely need a second physical box or a package slot for it to work smoothly.
Option 3 — Virtual mailbox service Services like Anytime Mailbox or PostScan Mail give you a separate business address that forwards to you digitally. No physical mailbox needed.
| Situation | Can you have 2+ mailboxes? | How |
|---|---|---|
| Single-family home, 1 address | No (1 curbside max) | Add PO Box for extras |
| Home with separate unit/address | Yes | Register each unit with USPS |
| Multi-unit building | Yes (required) | 1 box per unit, clearly labeled |
| Multiple properties | Yes | 1 box per address |
| Home + business same address | Partial | PO Box or suite designation |
| Rental of PO Boxes | Yes (unlimited) | Apply at local post office |
🏠 Upgrading your mailbox setup? If you're adding a second unit to your property or simply want to replace your existing mailbox with something more secure and modern, browse our locking modern mailboxes — USPS-compliant, available in wall-mount and post-mount styles from $99. A secure locking mailbox is the single most effective upgrade for a property receiving high mail volume.
How to Set Up a Second Mailbox Legally
If your situation qualifies for a second mailbox, here's the correct process :
Step 1 — Register the address or unit with USPS Go to usps.com or visit your local post office and register the new address or unit designation. Without this, your carrier won't know to deliver to the second box.
Step 2 — Choose a USPS-compliant mailbox The mailbox must meet USPS size standards — minimum interior dimensions of 3" H x 4" W x 15" L for curbside installation. It must also display the address or unit number clearly.
Step 3 — Install at the correct height and position Curbside mailboxes must be installed 41 to 45 inches from the road surface to the mailbox floor, and 6 to 8 inches from the curb. If you're adding a wall-mounted mailbox for a secondary unit, placement must be accessible without entering the property.
Step 4 — Notify your mail carrier Leave a note in your existing mailbox informing the carrier of the new setup. Carriers appreciate a heads-up and it prevents delivery errors during the transition.
Step 5 — Update your address with senders For business mail especially, update your address with all senders, the IRS, your bank, and any subscription services to start routing to the correct box from day one.
🔒 Security tip for multiple mailboxes If you're running two delivery points — especially one for business — use a locking mailbox for at least one of them. Unsecured business mail is a common target for identity theft. Our replacement cam locks fit most standard residential mailboxes and install in under 5 minutes.
FAQ
Can I have two mailboxes at the same address? Not as two separate curbside delivery points at an identical address. USPS allows one curbside mailbox per address. For two delivery points, you need a distinct unit designation (e.g., 123 Main St vs 123A Main St) or a PO Box as the second option.
Can I have a PO Box and a home mailbox at the same time? Yes — PO Boxes are separate from residential delivery and don't count as a second curbside mailbox. You can have both simultaneously. Many homeowners use a PO Box for business or sensitive mail while keeping standard delivery at home.
How many PO Boxes can I rent? There's no official limit on the number of PO Boxes you can rent. Each one requires a separate application and fee, starting around $10-30/month depending on size and location.
Do I need USPS permission to add a mailbox for a rental unit? You don't need formal permission, but you do need to register the unit address with USPS so carriers know to deliver to it. Without registration, the box will be ignored on the delivery route.
Can a business have more than one mailbox? Yes. Businesses can have multiple mailboxes at a commercial address, provided each is clearly labeled by department or purpose and accessible to the carrier.
What's the cheapest way to have a second mailbox? Renting a PO Box is the simplest and most affordable option — starting at around $10/month at most post offices. It requires no installation and gives you a completely separate, secure delivery point.
Can I install a wall-mounted mailbox in addition to my curbside mailbox? Only if it serves a different registered address or unit. A wall-mounted mailbox at the same address as an existing curbside box creates two delivery points for the same address — USPS will only deliver to one. Pick the one you want as your primary delivery point and register it accordingly.
