For homeowners

Types of mailbox: which one fits your address?

Choose Traditional curbside mailbox for addresses with curbline delivery (USPS Postal Operations Manual); Large-capacity curbside mailbox for holding small packages (USPS Postal Bulletin); Locked mail-slot curbside mailbox for locking incoming mail at the curb, with security the standard calls "non-USPS-tested" (USPS mailbox standard); Locked large-capacity curbside mailbox for keeping incoming mail behind a lock tested against pry tools (USPS mailbox standard); Wall-mounted mailbox for addresses with door delivery, using a house-mounted box (USPS Postal Operations Manual); Door mail slot for addresses with door delivery, using a slot in the door (USPS Postal Operations Manual).

The right choice depends on the delivery mode USPS uses at your address, whether incoming mail needs a lock, and whether the box must hold small packages.

How we know: By InstaBids editorial team with AI research agents. · Sources read: 22 October 2026 · Updated 27 October 2026

For every type here, the USPS Postal Operations Manual (2020) says "The type of mail receptacle depends on the mode of delivery in place." The four curbside types follow the USPS curbside mailbox standard; the wall-mounted box and the door slot follow the Postal Operations Manual and USPS's mailbox installation page.
Type	Best for	Main advantages	Main drawbacks
Traditional curbside mailbox	addresses with curbline delivery (USPS Postal Operations Manual)	may have a rear door, so mail can be taken out without standing in the street (USPS mailbox standard)	limited capacity: tested with a gauge 18.50 inches long x 5.00 inches wide x 6.00 inches high (USPS mailbox standard); no locks, locking devices or inserts on rural and highway contract routes (USPS Postal Operations Manual)
Large-capacity curbside mailbox	holding small packages (USPS Postal Bulletin)	expanded capacity: tested with a gauge 16.00 inches long x 13.00 inches wide x 7.00 inches high (USPS mailbox standard); may have a rear door, so mail can be taken out without standing in the street (USPS mailbox standard)	no locks, locking devices or inserts on rural and highway contract routes (USPS Postal Operations Manual)
Locked mail-slot curbside mailbox	locking incoming mail at the curb, with security the standard calls "non-USPS-tested" (USPS mailbox standard)	no official source names one	meets only the limited-capacity requirements (USPS mailbox standard); carriers do not open locked boxes and do not accept keys (USPS Postal Operations Manual)
Locked large-capacity curbside mailbox	keeping incoming mail behind a lock tested against pry tools (USPS mailbox standard)	expanded capacity: tested with a gauge 16.00 inches long x 13.00 inches wide x 7.00 inches high (USPS mailbox standard); the locked design USPS marks "USPS preferred" (USPS Postal Bulletin)	carriers do not open locked boxes and do not accept keys (USPS Postal Operations Manual)
Wall-mounted mailbox	addresses with door delivery, using a house-mounted box (USPS Postal Operations Manual)	no official source names one	replacing a curbside mailbox with one needs your local postmaster's permission (USPS); may only be used for items with postage (USPS)
Door mail slot	addresses with door delivery, using a slot in the door (USPS Postal Operations Manual)	can take an inside hood that keeps people from seeing into your home (USPS)	the opening must be at least 1-1/2 inches wide and 7 inches long (USPS Postal Operations Manual); must sit no less than 30 inches above the finished floor line (USPS Postal Operations Manual)

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If your priority is...
Priority	Choose
door delivery, with mail kept in a house-mounted box (USPS Postal Operations Manual)	Wall-mounted mailbox
door delivery, with mail coming through the door (USPS Postal Operations Manual)	Door mail slot

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Sources for the facts on this page

U.S. Postal Service, Postal Operations Manual section 632, Mail Receptacles (revisions through July 31, 2020), government, read 22 October 2026.
U.S. Postal Service, USPS-STD-7C Standard Mailboxes, Curbside, government, read 22 October 2026.
U.S. Postal Service, Postal Bulletin 22702 (May 14, 2026), Mailbox Improvement Week, government, read 22 October 2026.
U.S. Postal Service, How to Set Up and Mount a Mailbox (usps.com), government, read 22 October 2026.