Your USPS delivery mode decides most of this for you. If your carrier delivers to the curb from a vehicle, you need a curbside box on a post. If your carrier walks to your door, you can use a wall mount mailbox or a door slot. Within that choice, pick for security, package capacity and how much mail you get.
Below we compare a post mount mailbox and a wall-mounted box side by side, explain the USPS rules that apply to each, and cover locking options, packages, mail slots and through-the-wall boxes.
Wall mount vs post mount mailbox: the quick comparison
| Factor | Post-mount (curbside) | Wall-mount (door delivery) |
|---|---|---|
| USPS delivery mode | Curbside: the carrier serves it from the vehicle | Door delivery: the carrier walks to the house |
| USPS approval | Must be an approved model (Postmaster General seal) or approved by your postmaster | No Postmaster General seal required |
| Placement rule | 41 to 45 inches from the road surface to the bottom of the box or point of mail entry, 6 to 8 inches back from the curb | Near the main entrance, where the carrier can easily see it |
| Installation | Dig or surface-mount a post; call 811 before digging | A few screws into siding, brick or masonry |
| Package capacity | Larger boxes available, including package mailboxes with anti-fishing chutes | Usually letters, flats and catalogs; small parcels only in larger units |
| Theft exposure | Higher: away from the house, exposed to drive-by theft and vandalism | Lower: next to your door, in view |
| Snowplow and vehicle damage | Possible | Rare |
| Newspapers | A separate newspaper holder can go on the post | Newspapers may not go in the mailbox |
Start here: which delivery mode does your address have?
USPS assigns a mode of delivery to every address: curbside, sidewalk, door, or centralized (a cluster box). The type of mailbox you are allowed to use follows from that mode, not from what you prefer.
- Curbside or sidewalk delivery: you need a curbside mailbox that meets USPS Standard 7, mounted on a post or other support.
- Door delivery: you can use a house-mounted box approved by your postmaster or a door slot.
- Centralized delivery: your mail goes to a cluster box unit, and you do not choose a wall or post box at all.
The easiest way to check is to look at your neighbors. If every house on the street has a box at the curb, you are almost certainly on curbside delivery. If in doubt, ask your carrier or the local post office.
Can I switch from a curbside mailbox to a wall mailbox?
Usually not on your own. USPS says that to replace a curbside mailbox with a wall-mounted mailbox, you must get your local postmaster's permission (USPS mailbox guidelines). The Postal Operations Manual also says the existing mode of delivery stays with a home when it is sold, and new deliveries in an existing block normally get the same type of service as the older ones (POM section 631).
The main exception is hardship. A change can be considered when the current mode would impose an extreme physical hardship on a customer. The request is made in writing to the postmaster, is judged on humanitarian rather than economic grounds, and must be renewed every year. When the need ends, service returns to the mode used in the area.
Going the other way, from door delivery to curbside, also needs the Post Office to agree. Plan your purchase around the mode you have today.
Post-mount mailboxes: pros, cons and rules
A post-mounted mailbox is the standard for suburban and rural streets with curbside delivery. It is what most people mean by a "mailbox."
Pros
- Works for curbside delivery, the most common mode outside dense city neighborhoods.
- The widest choice of sizes, including large and package mailboxes.
- The carrier can deliver without leaving the vehicle, which matters for the outgoing-mail flag too.
- Room for a newspaper holder and address numbers on the post.
Cons
- More exposed to mail theft, vandalism, snowplows and cars.
- Requires a post installation, which means digging or a surface-mount base.
- Must meet height and setback rules and keep a clear approach for the carrier.
USPS rules for post-mounted mailboxes
A curbside box must be an approved model under USPS Standard 7 (look for the Postmaster General's seal), or a custom box your local postmaster approves. USPS asks you to position it 41 to 45 inches from the road surface to the bottom of the box or point of mail entry, and 6 to 8 inches back from the curb. If you have no raised curb, ask your postmaster. Our guide on how high a mailbox should be covers measuring in detail.
For the post itself, USPS points to Federal Highway Administration advice: a 4 x 4 inch wooden support or a 2 inch diameter steel or aluminum pipe, buried no more than 24 inches deep, that will bend or fall away if a car hits it. Local and state rules can be stricter. See how to install a mailbox and post for the step-by-step.
Wall-mount mailboxes: pros, cons and rules
A wall-mounted mailbox hangs on the house next to the front door. It is common in older city neighborhoods, townhouses and homes with door delivery.
Pros
- Close to the door: you collect mail without walking to the street, and it is in view of the house.
- No post to install and nothing for a plow or car to hit.
- Huge range of styles, from traditional cast aluminum to modern stainless steel.
Cons
- Only an option with door delivery (or with postmaster permission).
- Most hold letters, flats and catalogs, not parcels.
- Newspapers may not be placed in it.
USPS rules for wall-mounted mailboxes
Wall-mounted mailboxes are not required to have a Postmaster General seal of approval. USPS asks that the box hold a normal day's mail, including letter-size envelopes, postcards and catalogs, and that it sit near the main entrance where the carrier can easily see it. Only items with postage may go in it. Your postmaster still approves house-mounted boxes for door delivery, so check before you drill.
Locking options: wall mount vs post mount
Both styles come in locking versions. A locking mailbox has a slot or chute the carrier drops mail through and a locked door only you open. USPS carriers do not open locked boxes or accept keys, so the slot has to be large enough for your normal daily mail (DMM 508).
- Locking wall mount mailbox: the Mail Boss Townhouse Security Locking Wall Mount Mailbox is 14.75 x 15.4 x 7.15 inches (H x W x D), built from 14 and 16 gauge electro-galvanized steel with a 12-disc wafer lock, a patented anti-pry latch and 3 keys. It mounts to the wall and can also go on a Mail Boss post.
- Locking post mount mailbox: the Mail Boss Mail Manager Mailbox and Post pairs an 11.25 x 10.75 x 21 inch steel box with a 43 inch in-ground post or a shorter surface-mount post. Its baffle door accepts mail bundles and small packages up to 3.5 inches high by 10.2 inches wide while preventing fishing, and it is marked approved for curbside delivery.
For a deeper look at security levels, read our locking mailbox buying guide.
Package capacity: which holds more?
Post-mounted boxes win on packages. Curbside package mailboxes have a large hopper or chute that takes small parcels and stops anyone reaching back in. A typical wall box is shallow (the Townhouse above is 7.15 inches deep) and is sized for letters and catalogs.
If you have door delivery and want parcel capacity, look at a larger wall unit or a separate porch package box next to the door. If you have curbside delivery, a package mailbox on a post is the most practical answer.
Mail slots and through-the-wall mailboxes
A mail slot is a third option for door delivery. USPS sets the specifications:
- The opening must be at least 1-1/2 by 7 inches.
- The bottom of the slot must be at least 30 inches above the floor.
- Horizontal slots need a flap hinged at the top; vertical slots hinge on the side opposite the door's hinges.
- If you add an inside privacy hood, it must project at least 2-1/16 inches beyond the inside face of the door.
A through-the-wall mailbox takes the slot idea further: the carrier drops mail into a slot on the outside wall, and you retrieve it from a locked door inside the house or garage. It suits new builds and remodels where you can frame the opening. The Jayco Industries Vertical Wall Mount Letter Locker is designed for recessed installation, has a 4-1/2 x 10-3/4 inch incoming slot and a USPS 5-pin cylinder lock, and holds about 2 to 3 days of mail. Confirm the access side (front or rear) when you order.
Ask before you buy the mounting hardware
Customers sometimes pick a mount first and get the post office's answer later. One had to send back their mounting parts and buy in-ground hardware after USPS refused the installation they had planned. Once a mailbox is installed, it counts as used and cannot be returned, so settle this before anyone drills.
Check the wall too. Locking wall boxes such as the Metro, Olympus and Townhouse are among our best sellers, but heavy steel is a different job from a light tin box. One customer found theirs too heavy for the spot they had in mind. Confirm the wall can carry it, and use fasteners made for that wall.
Which one should you choose?
- Confirm your delivery mode. Curbside means a post-mount box. Door delivery means wall-mount, slot or through-the-wall.
- Decide on security. If mail theft is a concern on your street, choose a locking model with an anti-fishing door or chute.
- Size it for your mail. Count how many small packages you get each week. Frequent parcels push you toward a package mailbox on a post (or a porch package box for door delivery).
- Check the site. For a post: call 811 before digging, check HOA rules and your state's roadside rules. For a wall: check the wall material and leave the box visible from the walk.
- Ask your postmaster before installing anything new or changing location. The local postmaster has the final say.
Wall and post mount questions
Can I return a wall mailbox after it is mounted?
No. Once a mailbox is installed, it counts as used and cannot be returned.
Do wall-mounted mailboxes need to be USPS approved?
No. USPS says wall-mounted mailboxes are not required to have a Postmaster General seal. They must hold a normal day's mail and sit near the main entrance. Curbside boxes do need to be an approved model.
Can I replace my curbside mailbox with a wall mailbox?
Only with your local postmaster's permission. Your address's delivery mode normally stays the same, and changes are generally approved for cases like extreme physical hardship.
Is a wall mount mailbox more secure than a post mount mailbox?
Usually, because it sits by your door in view of the house. A locking post-mount box with an anti-fishing door narrows the gap for curbside addresses.
How big does a mail slot have to be?
USPS requires a clear opening of at least 1-1/2 by 7 inches, with the bottom of the slot at least 30 inches above the finished floor.
Can a mail carrier put newspapers in my wall mailbox?
No. USPS says newspapers may not be placed in wall-mounted mailboxes. With curbside delivery, a separate newspaper holder can go on the post below the mailbox.
Shop wall and post mount mailboxes
Browse our wall-mounted mailboxes for door delivery, or a complete mailbox with post for curbside delivery. Not sure which fits your address? Contact us and we will help you choose.
******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******