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4C Horizontal Mailboxes

Recessed Mounted 4C Mailboxes are available in the following heights:

Note: Drawings shown are for your quick reference only. For specific standards, consult local building codes and USPS requirements in your region.


4C Mailbox Accessories
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Understanding USPS 4C Mailboxes (a.k.a., recessed CBU mailboxes)

Effective October 2006, the USPS issued the STD-4C standard for USPS commercial mailboxes. This updated standard applies to all recessed 4C mailboxes and replaces the STD-4B+ horizontal mailbox for every new construction development or project in the U.S.

The biggest improvements from the previous 4B specification are the 4C's door size and overall security. Each tenant door is 12 inches wide by 15 inches deep by 3 inches high, meaning that larger envelopes and magazines arrive flat as they were intended.

The STD-4C standard also requires one (1) parcel locker for every ten (10) tenant compartments -- all of our preconfigured units adhere to this requirement. As for overall mail security, our manufacturers must adhere to the stricter and more thorough lock design requirements.

4C Mailbox Materials & Specifications

Made of aluminum with stainless steel hardware for locks and door mechanisms, these units are ideal for both indoor and outdoor applications.

  • 4C tenant door specifications: 3 in. H x 12 in. W x 15 in. D.
  • Finish & material: heavy gauge aluminum construction available in four color options by Salsbury Industries and eight color options by Auth-Florence.
  • Loading and mounting: available in either front or rear loading configurations (explained in detail below).
  • Tenant doors: include heavy duty, stainless steel dustproof cam locks (each with 3 keys).
  • Parcel lockers: for USPS package delivery. The dual, captive locking system allows the USPS to deliver a package to the locker while leaving the key in the tenant's mailbox. The package is retrieved by the tenant and key is retained securely in the lock. See video below for details.


  • Outgoing mail: all units feature an outgoing mail compartment with a drop-off slot, anti-fish comb for security, and protective hood located above USPS access door for convenient outgoing mail drop-off and collection.
  • Door identification: attractive silver placards with black numbers (1 through 20) are included with every standard configuration. Custom numbering can also be selected prior to checkout.

Front Loading Wall Mount

Between Salsbury Industries and Auth Florence Manufacturing, we offer one of the largest selections of front-loading USPS Approved 4C mailboxes and accessories online with over 150+ preconfigured modules to choose from

Front-loading mailboxes include a Master Loading Door prepared for the USPS Arrow Lock, which provides easy access to all compartments by the US mail carrier.

Front-load units are usually more common as they are immediately accessible from the front (as you might have already guessed), whereas rear loading units require the mail carrier to load and retrieve mail from a secure room located behind the recessed mailbox (more about rear loading below).

Rear Loading Wall Mount

You can probably guess that the rear-loading mailbox is accessed from the back. These mailboxes include hinged and latching rear doors that are accessed by a secure mail room for USPS use. Since there is no locking mechanism on the rear doors, a secure mail room behind mailboxes is required to keep mail secure.

If you still aren't sure whether you need a front or rear loading configuration, contact us and we will help you decide on the best option to fit your specific needs.

4C Pedestal

The 4C pedestal mailbox includes all of the features of the 4C horizontal wall units, but the addition of a pedestal means these units are outside of USPS specifications and therefore for private use only (unless you obtain approval from your local postmaster prior to purchase and installation). If you intend to purchase a 4C pedestal mailbox for U.S. mail delivery, we strongly recommend that you contact your local postmaster for approval.

4C Mailbox Enclosures

On every 4C horizontal product page, we offer the option to purchase with a mail station kiosk specifically designed to house the recessed mailbox being purchase. However, we also list 4C enclosures and surface mount collars as stand-alone products for customers looking to replace existing units.

4C Accessories

Whether you need new door identification tags or replacement locks or keys, we carry the full selection of 4C accessories from both of Salsbury Industries and Auth Florence Manufacturing.

Looking for a specific part number? Search our site or chat with one of our reps and we will help you locate it.

MAX HEIGHT SUITE

Actual: 56-1/2H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 55-9/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C16D-20
(20 MB1, 2 PL15)
4C16D-19
(19 MB1, 2 PL15)
4C16D-09
(7 MB2, 2 MB3, 2 PL15)
4C16D-07
(1 MB2, 6 MB3, 2 PL15)
4C16S-09
(9 MB1, 1 PL15)
4C16S-04
(3 MB2, 1 MB3, 1 PL15)
4C16S-03
(3 MB3, 1 PL15)
# Mailboxes (Total)201997943
# Parcel Lockers (Total)2222111
# Collection1111111
# BINS0000000
# Mailboxes Under 488733311
Module Weight (lbs)171163157140978162

15 HIGH SUITE

Actual: 54-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 53-3/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C15D-18
(18 MB1, 2 PL5)
4C15D-17
(17 MB1, 1 PL5, 1 PL6)
4C15D-16
(16 MB1, 2 PL6)
4C15D-09
(9 MB2, 2 PL5)
4C15S-08
(8 MB1, 1 PL5)
4C15S-07
(7 MB1, 1 PL6)
4C15S-04
(4 MB2, 1 PL5)
# Mailboxes (Total)1817169874
# Parcel Lockers (Total)2222111
# Collection1111111
# BINS0000000
# Mailboxes Under 488763321
Module Weight (lbs)160158156144878579

MAX HEIGHT SUITE

Actual: 56-1/2H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 55-9/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4C16D-29*
(29 MB1)
4C16S-14*
(14 MB1)
4C16S-HOP
4C16S-BIN
4C16D-8P
(4 PL3, 1 PL4, 1 PL5, 1 PL15)
4C16D-6P
(3 PL4, 1 PL5, 2 PL6)
4C16S-3P
(1 PL15, 1 PL5, 1 PL6)
Model
(Compartment Types)
291400000# Mailboxes
0000863# Parcel Lockers
1110000# Collection
0002000# BINS
17800000# MB under 48
17096766511310525Module Weight

15 HIGH SUITE

Actual: 54-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 53-3/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4C15D-28*
(28 MB1)
4C15D-13*
(11 MB2, 2 MB3)
4C15S-13*
(13 MB1)
4C15S-06*
(5 MB2, 1 MB3)
4C15S-HOP
4C15S-BIN
4C15S-3P
(3 PL5)
Model
(Compartment Types)
2813136000# Mailboxes
0000003# Parcel Lockers
1111100# Collection
0000020# BINS
18783000# MB under 48
1221429579746375Module Weight

14 HIGH SUITE

Actual: 51-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 50-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C14D-16
(16 MB1, 2 PL5)
4C14D-15
(15 MB1, 1 PL5, 1 PL6)
4C14D-14
(14 MB1, 2 PL6)
4C14D-07
(7 MB2, 2 PL6)
4C14S-07
(7 MB1, 1 PL5)
4C14S-03
(3 MB2, 1 PL6)
# Mailboxes (Total)161514773
# Parcel Lockers (Total)222211
# Collection111111
# BINS000000
# Mailboxes Under 48876331
Module Weight (lbs)137130109997256

13 HIGH SUITE

Actual: 47-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 46-13/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C13D-16
(16 MB1, 2 PL4)
4C13D-15
(15 MB1, 1 PL 4, 1 PL5)
4C13D-14
(14 MB1, 2 PL5)
4C13D-13
(13 MB1, 1 PL5, 1 PL6)
4C13D-12
(12 MB1, 2 PL6)
4C13D-07
(7 MB2, 2 PL5)
# Mailboxes (Total)16151413127
# Parcel Lockers (Total)222222
# Collection111111
# BINS000000
# Mailboxes Under 481098763
Module Weight (lbs)129127125123121114

14 HIGH SUITE

Actual: 51-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 50-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4C14D-26*
(26 MB1)
4C14D-13*
(13 MB2)
4C14S-12*
(12 MB1)
4C14S-06*
(6 MB2)
4C14S-HOP
4C14S-BIN
4C14S-3P
(1 PL4, 2 PL5)
4C14S-2P
(2 PL6)
Model
(Compartment Types)
26131260000# Mailboxes
00008632# Parcel Lockers
11111001# Collection
00000200# BINS
189840000# MB under 48
145101765672585655Module Weight

13 HIGH SUITE

Actual: 47-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 46-13/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4C13S-06
(6 MB1, 1 PL5)
4C13S-05
(5 MB1, 1 PL6)
4C13S-03
(3 MB2, 1 PL5)
4C13D-24*
(24 MB1)
4C13D-11*
(9 MB2, 2 MB3)
4C13S-11*
(11 MB1)
4C13S-HOP
4C13S-BIN
4C13S-2P
(2 PL6)
Model
(Compartment Types)
653241111000# Mailboxes
111000002# Parcel Lockers
111111100# Collection
000000010# BINS
3211378000# MB under 48
68676413311272694557Module Weight

12 HIGH SUITE

Actual: 44-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 43-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C12D-12
(12 MB1, 2 PL5)
4C12D-11
(11 MB1, 1 PL5, 1 PL6)
4C12D-10
(10 MB1, 2 PL6)
4C12D-05
(5 MB2, 2 PL6)
4C12S-02
(2 MB2, 1 PL6)
# Mailboxes (Total)12111052
# Parcel Lockers (Total)22221
# Collection11111
# BINS00000
# Mailboxes Under 4887631
Module Weight (lbs)11611411210459

11 HIGH SUITE

Actual: 40-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 39-13/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C11D-20
(20 MB1)
4C11D-19
9(19 MB1)
4C11D-15
(15 MB1, 1 PL5)
4C11D-10
(10 MB1, 2 PL5)
4C11D-09
(9 MB1, 1 PL5, 1 PL6)
4C11D-05
(5 MB2, 2 PL5)
# Mailboxes (Total)2019151095
# Parcel Lockers (Total)001222
# Collection111111
# BINS000000
# Mailboxes Under 4811106100
Module Weight (lbs)123122119115113106

12 HIGH SUITE

Actual: 44-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 43-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4C12D-22*
(22 MB1)
4C12S-10*
(10 MB1)
4C12S-HOP
4C12S-BIN
4C12D-4P
(4 PL6)
4C12S-2P
(2 PL6)
Model
(Compartment Types)
22100000# Mailboxes
000042# Parcel Lockers
111000# Collection
000100# BINS
1880000# MB under 48
1246866459753Module Weight

11 HIGH SUITE

Actual: 40-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 39-13/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4C11S-09
(9 MB1)
4C11S-04
(4 MB1, 1 PL5)
4C11S-02
(2 MB2, 1 PL5)
4C11S-HOP
4C11S-BIN
4C11D-4P
(2 PL5, 2 PL6)
4C11S-2P
(1 PL5, 1 PL6)
Model
(Compartment Types)
9420000# Mailboxes
0110042# Parcel Lockers
1111000# Collection
0000100# BINS
5000000# MB under 48
56535065459945Module Weight

10 HIGH SUITE

Actual: 37-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 36-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C10D-18
(18 MB1)
4C10D-09
(9 MB2)
4C10D-06
(6 MB2, 1 PL6)
4C10S-08
(8 MB1)
4C10S-04
(4 MB2)
# Mailboxes (Total)189684
# Parcel Lockers (Total)00100
# Collection11111
# BINS00000
# Mailboxes Under 48105242
Module Weight (lbs)9784835647

ADA MAX HEIGHT

Actual: 37-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 36-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4CADS-03+
(3 MB1, 1 PL5)
4CADS-01+
(1 MB2, 1 PL6)
4CADS-2P+
(2 PL5)
Model
(Compartment Types)
310# Mailboxes
112# Parcel Lockers
110# Collection
000# BINS
310# MB under 48
494643Module Weight

10 HIGH SUITE

Actual: 37-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 36-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4C10S-BIN
4C10S-HOP
P 4C10D-4P
(4 PL5)
Model
(Compartment Types)
000# Mailboxes
004# Parcel Lockers
100# Collection
010# BINS
000# MB under 48
415280Module Weight

ADA MAX HEIGHT

Actual: 37-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 36-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4CADD-10+
(10 MB1, 2 PL4)
4CADD-09+
(9 MB1, 2 PL15)
4CADD-08+
(8 MB1, 2 PL5)
4CADD-07+
(7 MB1, 1 PL5, 1 PL6)
4CADS-04+
(4 MB1, 1 PL15)
# Mailboxes (Total)109874
# Parcel Lockers (Total)22221
# Collection11111
# BINS00000
# Mailboxes Under 48109874
Module Weight (lbs)9196888955

9 HIGH SUITE

Actual: 33-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 32-13/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C09D-16
(16 MB1)
4C09D-15
(15 MB1)
4C09D-10
(10 MB1, 1 PL6)
4C09D-06
(1 MB1, 5 MB3)
4C09D-04
(1 MB1, 3 MB3, 1PL6)
# Mailboxes (Total)16151064
# Parcel Lockers (Total)00101
# Collection11111
# BINS00000
# Mailboxes Under 48109442
Module Weight (lbs)8988847576

8 HIGH SUITE

Actual: 30-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 29-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C08D-14
(14 MB1)
4C08D-13
(13 MB1)
4C08D-09
(9 MB1, 1 PL5)
4C08D-07
(7 MB2)
4C08D-04
(4 MB2, 1 PL6)
# Mailboxes (Total)1413974
# Parcel Lockers (Total)00101
# Collection11111
# BINS00000
# Mailboxes Under 48109552
Module Weight (lbs)8180787271

9 HIGH SUITE

Actual: 33-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 32-13/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4C09S-07
(7 MB1)
4C09S-02
(2 MB1, 1 PL5)
4C09S-HOP
4C09S-BIN
N 4C09D-4P
(2 PL4, 2 PL5)
4C09S-2P
(1 PL4, 1 PL5)
Model
(Compartment Types)
720000# Mailboxes
010042# Parcel Lockers
111000# Collection
000100# BINS
400000# MB under 48
484552417640Module Weight

8 HIGH SUITE

Actual: 30-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 29-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4C08S-06
(6 MB1)
4C08S-03
(3 MB2)
4C08S-01
(1 MB1, 1 PL5)
4C08S-HOP
4C08S-BIN
4C08S-2P
(1 PL3, 1 PL5)
Model
(Compartment Types)
631000# Mailboxes
001002# Parcel Lockers
111100# Collection
000010# BINS
420000# MB under 48
444040524437Module Weight

7 HIGH SUITE

Actual: 26-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 25-13/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C07D-12
(12 MB1)
4C07D-06
(6 MB1, 1 PL6)
4C07D-05
(3 MB2, 2 MB3)
4C07D-03
(2 MB2, 1 MB3, 1 PL5)
4C07S-05
(5 MB1)
4C07S-1P
(1 PL6)
# Mailboxes (Total)1265350
# Parcel Lockers (Total)010101
# Collection111110
# BINS000000
# Mailboxes Under 481043140
Module Weight (lbs)736864654032

6 HIGH SUITE

Actual: 23-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 22-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C06D-10+
(10 MB1)
4C06D-09+
(9 MB1)
4C06D-05+
(5 MB1, 1 PL5)
4C06D-05X+
(5 MB2)
4C06D-04+
(4 MB1, 1 PL6)
# Mailboxes (Total)109554
# Parcel Lockers (Total)00101
# Collection11111
# BINS00000
# Mailboxes Under 48109554
Module Weight (lbs)6665596261

6 HIGH SUITE

Actual: 33-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 32-13/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

4C06D-02+
(2 MB2, 1 PL6)
4C06S-04+
(4 MB1)
4C06S-02+
(2 MB2)
4C06D-2P+
(2 PL6)
4C06S-1P+
(1 PL6)
Model
(Compartment Types)
24200# Mailboxes
10021# Parcel Lockers
11100# Collection
00000# BINS
24200# MB under 48
5836335328Module Weight

5 HIGH SUITE

Actual: 19-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 18-13/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C05D-08+
(8 MB1)
4C05D-07+
(7 MB1)
4C05D-03+
(3 MB1, 1 PL5)
4C05S-03+
(3 MB1)
4C05D-2P+
(2 PL5)
4C05S-1P+
(1 PL5)
# Mailboxes (Total)873300
# Parcel Lockers (Total)001021
# Collection111100
# BINS000000
# Mailboxes Under 48873300
Module Weight (lbs)585755314926

4 HIGH SUITE

Actual: 16-1/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 15-5/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C04D-06+
(6 MB1)
4C04S-02+
(2 MB1)
4C04D-2P+
(2 PL4)
4C04S-1P+
(1 PL4)
# Mailboxes (Total)6200
# Parcel Lockers (Total)0021
# Collection1100
# BINS0000
# Mailboxes Under 486200
Module Weight (lbs)50574623

3 HIGH SUITE

Actual: 12-3/4H x 31-9/16W (Double) or 17-1/2W (Single) x 17D / Rough Opening: 11-13/16H x 30-5/16W (Double) or 16-1/4W (Single) x 17D

Model
(Compartment Types)
4C03D-04+
(4 MB1)
4C03S-01+
(1 MB1)
4C03D-2P+
(2 PL3)
4C03S-1P+
(1 PL3)
# Mailboxes (Total)4100
# Parcel Lockers (Total)0021
# Collection1100
# BINS0000
# Mailboxes Under 484100
Module Weight (lbs)42233820
Frequently Asked Questions
Question: Do you sell curbside parcel locking mailboxes?
Answer: Yes, you can view our Curbside Parcel Locking Mailbox Selection for more details. Call us at (866) 707-0008 for further assistance. Thank you.

Question: I am a manager of a self storage facility. I am interested in some information on mailboxes that could be installed and then rented in the office of my facility.
Answer: You have the option of rear or front loading. The most cost-effective option, if you can use the rear loading, is the aluminum mailboxes. If there is a need for front loading, you will need to go with a 4B Horizontal. Both items are USPS approved.

4C Horizontal Mailboxes
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