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Sheet Metal Mailbox: The Comprehensive Guide

Sheet Metal Mailbox

In this guide, you will find all information you are looking for about sheet metal mailboxes.

I know probably you want to choose the best material, and learn about the fabrication process, features, surface finish options, benefits, etc.

Whichever the case, this guide provides in-depth information about sheet metal letterboxes.

So, before buying your next mailbox, read this guide.

Table of contents hide

What is Sheet Metal Mailbox?

A mailbox is a fabricated enclosure specially designed for letters. Their design ensures letters are safe in all weather conditions.

They are made from many materials hence the names, sheet metal mailbox, plastic mailbox, or wooden mailbox.

For this guide, we will focus on sheet metal as the primary material.

At times, you can also refer to mailboxes as letterboxes or postboxes.

Best Sheet Metal for Fabricating Mailbox

Sheet Metal Mailbox
Sheet Metal Mailbox

When it comes to sheet metal letter box fabrication, you can choose:

  • Aluminum
  • Galvanized steel
  • Stainless steel
  • Bronze
  • Brass

So, what is unique about these materials?

Sheet Metal Mailbox MaterialAdvantages of Each Sheet Metal for Mailbox Fabrication
Aluminum·         Lightweight

·         Excellent corrosion resistance

·         Can withstand all weather conditions

·         Easier to fabricate any mailbox design

·         Allows for numerous surface finishes

·         Durable

·         For extremely harsh weather conditions, you may require additional treatments such as powder coating

·         Guarantees low maintenance cost

Stainless Steel·         Durable

·         Superior corrosion resistance due to chromium content

·         Easy to fabricate mailboxes

·         Allow for many surface finishes

·         Heavier than aluminum mailboxes

·         Offer excellent protection in salty water environments

·         At times, chlorine may compromise corrosion resistance properties, especially for some grades

Galvanized Steel·         Durable mailbox

·         Thin zinc coating guarantees excellent resistance to corrosion

·         Although it can withstand extreme weather conditions, salty water can be problematic

·         Heavier than aluminum mailboxes

Bronze·         Redder coloring gives bronze mailboxes a richer look

·         Corrosion resistant

·         Elements such as moisture, sulfides, or chlorine may cause deterioration

Brass·         Not very popular due to the high level of maintenance required

·         Although it offers better aesthetic appearance, brass mailboxes may develop a patina

·         It requires regular polishing to maintain the elegant look

Zinc coated iron·         Cast iron mailboxes are heavier than aluminum mailboxes

·         Zinc coating prevents iron from rusting

·         In case the zinc coating deteriorates, the iron mailbox will rust


Apart from these 6 materials for mailboxes, you may use other sheet metals such as copper, titanium, or gold mailbox. The material type will depend on your bespoke mailbox needs.

Sheet Metal Mail Box Classification

There are many types of sheet metal mailboxes available in the market. You can find standard and custom sheet metal mailboxes.

Remember, the custom sheet metal letter boxes are fabricated according to your unique specifications. Therefore, when it comes to custom mailboxes, the options are unlimited.

Let’s explore some common types of mailboxes:

Types of Mailboxes Based on Material Type

There are many materials you can use to fabricate mailboxes such as aluminum, steel, brass, etc. The best part, you can use material type to classify mailboxes as you can see below:

· Aluminum Mailbox

You may have cast aluminum wall mount mailbox. They are made from aluminum.

Aluminum Mailbox
Aluminum Mailbox

· Galvanized Steel Mailbox

Galvanized steel is the primary material in these mailboxes. A good example is the galvanized steel silver mailbox

Galvanized Steel Mailbox
Galvanized Steel Mailbox

· Stainless Steel Mailbox

Stainless material is one of the best mailbox materials. A good example is the stainless steel outdoor mailbox.

Stainless Steel Mailbox
Stainless Steel Mailbox

· Brass Mailbox

These mailboxes are made from brass material. They come in many decorative features and designs.

Polished Brass Mailbox
Polished Brass Mailbox

· Bronze Mailbox

Bronze forms a greater percentage of these mailboxes. You will find most bronze mailboxes in antique designs and shapes.

Bronze Mailbox
Bronze Mailbox

Ideally, your mailbox supplier may name these accessories depending on the materials they use during the fabrication process.

Classification Based on Mounting Options

You should install a letter box in a secure and easy-to-access location. Therefore, this makes the installation mechanism an important aspect.

Again, you can use the mounting or installation mechanism as classification criteria.

Well, we have these options:

· Post Mount Metal Mailbox

You will install these letter boxes on posts.

Post Mount Mailbox
Post Mount Mailbox

· Wall Mounted Metal Mailbox

These are letter boxes mounted on wall sections.

Wall Mount Mailbox
Wall Mount Mailbox

· Freestanding Mailbox

You can install these mailboxes directly on the floor. Depending on the design, you must make a base or decide to install it without making any platform.

Floor Mount Metal Mailbox
Floor Mount Metal Mailbox

· Column Mount Mailboxes

They have special features allowing you to mount the letter boxes on stone or brick columns.

Column Mount Metal Mail Box
Column Mount Metal Mail Box

· Pedestal Mailbox

A pedestal is a support, platform, or base where you install a mailbox. For this reason, they are called pedestal mailboxes. Their stands have unique decorations.

Pedestal Mailbox
Pedestal Mailbox

Classify Types of Mailbox Depending on Size and Design

Fabricated sheet metal mailboxes come in many sizes and designs. In fact, with the two parameters, you can have unlimited classification criteria.

However, to make this simple, you may have:

Mailbox Size
Mailbox Size

· Small Mailbox

Although small may be relative, in most cases these letter boxes have 250mm length, 150mm width, and 20mm height. Also, you can still get smaller letterboxes than this.

· Medium Size Mailbox

Their sizes are slightly bigger than the small mailbox. However, they are smaller than extra-large metal mailboxes.

· Extra Large Metal Mailbox

They are the biggest mailboxes available in the market. A good example is the letterbox made by Jim Bolim with a 162.63m3. Of course, with the advancement in technology, you can expect even larger and more irregular designs.

· Square Mailbox

These letter boxes have a square shape.

Square mailbox
Square Mailbox

· Rectangle Mailbox

The letter boxes have a rectangular shape.

Rectangle Mailbox
Rectangle Mailbox

Of course, there are irregular shapes that do not conform to standard geometrical shapes. Also, you may find mailboxes with more than one geometrical shape.

Where to Use Mailbox as a Classification Criteria

These types of mailboxes refer to the exact locations where you install the mail drop boxes. It implies you may have:

· Residential Mailboxes

As the name suggests, these are letter boxes designed for use in residential areas.

 Residential Mailbox
Residential Mailbox

· Commercial Mailboxes

You can install these mailboxes within commercial premises. Depending on the specific locations, you can classify these mailboxes types as:

  • Apartment mailboxes
  • Recesses lobby mailboxes
  • Private delivery mailboxes
Apartment Mailbox
Apartment Mailbox

Furthermore, you can install commercial mailboxes either indoors or outdoors. As a result, we have other letterbox categories such as:

  • Outdoor mailbox
  • Indoor mailbox

Classifying Mailboxes According to Functionality

A mailbox’s functionality or use is an important classification criterion. When it comes to functionality, features play a fundamental role.

Some common options are:

· Mail Slots

It is a small opening, which is either square or rectangular. You can use the opening to receive letters or insert a letter into a box.

Mail Slot
Mail Slot

· Package Drop Boxes

These are special boxes where you can drop packages safely. You can install package drop boxes in both commercial and residential areas.

· Cluster Mailboxes

Cluster mailboxes are mainly wall-mounted letterboxes. They are many mailboxes installed together. Usually, there is a slot for each mailbox.

Cluster Metal Mailbox
Cluster Metal Mailbox

Figure 18 Cluster metal mailbox

· Novelty Mail Boxes

Novelty mailboxes are customized to your unique designs. You may decide to have a mailbox resembling fish, pet, dinosaur, etc.

Ideally, they add extreme personality.

Novelty Mailbox
Novelty Mailbox

· Outgoing Mailbox

These mailboxes are designed for outgoing letters. Modern mailbox designs have slots for both incoming and outgoing mails.

· Collection Box

It resembles the normal post-mounted mailbox. However, the design is such that the front section has a slot for inserting the mail. While at the back end, there is an opening for retrieving the mail.

At times, you can refer to the collection mailbox as the rear access mailbox.

· Anti-pry Mailbox

Anti-pry mailboxes have more advanced security features than normal letterboxes. They have a plate that automatically covers the slot for inserting letters.

The anti-pry feature prevents possible identity and mail theft.

Anti Pry Mailbox
Anti Pry Mailbox

· Interlocking Mailbox

The interlocking mechanism is an important safety measure in mailboxes. The latching mechanism holds the door in place to ensure it does not swing thereby dropping letters.

· Locking Mailboxes

These letterboxes have a locking mechanism to ensure only authorized people access the mail.

· Parcel Mailbox

Parcel boxes are slightly bigger than normal mailboxes. Once you insert the parcel, they have a locking mechanism to prevent unauthorized people from accessing the parcel.

· Newspaper Mailbox

They feature slightly large slots to accommodate all newspaper sizes. More importantly, these mailboxes are specifically designed for newspapers.

· Decorative Metal Mailboxes

Although these mailboxes may serve the purpose of holding letters, their designs add aesthetic value to your building or house. They may have unique designs, coloring, or graphics.

Decorative Mail Box
Decorative Mail Box

Classify Letter Boxes Based on Manufacturing Techniques

Although there are many ways to manufacture letter boxes, welding, casting or fabrication remain viable options.

As a result, there are:

· Welded Mailboxes

It refers to mailboxes whose parts are partially or fully welded. Of course, welding forms part of the assembly process.

· Cast Mailboxes

These are mailboxes made through metal casting techniques. However, it does not imply that you will cast the entire mailbox.

You cast sections and then assemble them through riveting or welding.

In addition to these types of mailboxes, other parameters you may use to classify mailboxes are:

  • Color type where you may have a black mailbox, white mailbox, red-white mailbox, etc.
  • Types of finishing – these may include powder coated mailboxes, painted mailboxes, etc.

Again, for practicality, you may find mailboxes on sale that may fall into more than one classification criteria. Here are some good examples:

i. Standing galvanized steel mailbox

ii. Wall mounted galvanized sheet metal mailbox

iii. Wall mounted metal mailbox without lock

iv. Powder coated metal wall mount mailbox

v. Residential yellow sheet metal mailboxes

vi. Architectural post mount sheet metal mailboxes

vii. European style sheet metal mailboxes

viii. Heavy duty metal mailbox post

ix. Antique mailboxes or Vintage mailboxes

x. Flahart mailboxes

As you can see, there are many sheet metal mailbox types in the market. Therefore, before starting any mailbox fabrication process – be clear about the design you want.

Advantages of Mailbox Fabrication using Sheet Metal

Unlike plastic mailboxes, metal letterboxes offer many benefits. The key advantages include:

  • They are durable and can serve you for many years
  • Most sheet metal mailboxes are resistant to most harsh weather conditions
  • Offer better security and protection since they are unbreakable
  • Easy customization makes it easy to get the best metal mailboxes
  • With a suitable surface finish, these mailboxes are attractive
  • Compared to wood or steel, aluminum mailboxes are lightweight
  • Although the initial investment may be high, they are inexpensive to maintain
  • You can easily refurbish sheet metal mailboxes

Clearly, there are many reasons why you should consider sheet metal letterboxes.

Factors to Consider when Buying Sheet Metal Mailbox

Evaluating mailbox specifications will help you choose the perfect one for your business. So, whether you want a standard mailbox or a custom mailbox, you must evaluate every feature and specification.

Since we have discussed the key aspects of letterboxes, let’s have a quick checklist:

  1. Design
  2. Size/Capacity
  3. Accessibility – slots for inserting letters and how to retrieve the letter
  4. Installation mechanism
  5. Number of compartment
  6. Numbering or naming
  7. Complying with necessary standards such as USPS-STD-4B+
  8. Security and locking mechanism
  9. How to access the letters
  10. Cost of mailbox
  11. Material types
  12. Safety features
  13. Ability to withstand harsh weather conditions
  14. Possible customization options available

With these 14 points, you can get the best metal letterbox for any application.

Sheet Metal Mailbox Fabrication Process

Metal mailbox designing and fabrication can be an overwhelming task without the right information. A reason this section will show you how to make a metal mailbox in simple steps.

But, even before you design and fabricate a mailbox – know the parts of the mailbox:

Parts of Metal Mailbox
Parts of Metal Mailbox
Metal Mailbox PartFunction
Beam·         Common in post-mounted metal boxes

·         It holds the mailbox

Number plate/identification·         It identifies the address or mailbox location
Post/Pole·         It is the main member holding mailbox off the ground
Base·         Supports the pole and mailbox
Mounting frame·         Helps in mailbox installation or mounting
Mail slot/hole·         For dropping letters into the mailbox
Locking mechanism·         Ensures no authorized personnel access the mailbox
Mailbox access door·         For accessing the content in the mailbox
Anti-praying feature·         Added security preventing identity or mail theft
Hinges·         Holds mailbox access door in position
Latching mechanism·         Hold the mailbox door in position preventing the possibility of letters dropping
Mailbox frame·         A structure that holds mailbox panels in place
Side panels·         Are assembled forming a complete mailbox

Other parts may include support brackets, screws, window clips, nameplates, glass windows, and door frames, amongst others.

Remember, the parts vary depending on the specific metal mailbox design.

Next, you should proceed to the metal mailbox fabrication process:

Step 1: Design a Metal Mailbox

There are many CAD software you can use to make sheet metal mailbox plans. The dimensions must be accurate. Again, ensure you specify all possible elevations for easy mailbox fabrication.

Step 2: Choose Suitable Metal Mailbox Material

Depending on where you plan to use the letterbox, the available options include:

  • Stainless steel
  • Galvanized steel
  • Aluminum
  • Bronze
  • Brass, etc.

You should consider material availability alongside the ability to form and fabricate the metal.

Step 3: Cut Sheet Metal for Mailbox

Plasma cutting, laser cutting, saws, and Waterjet cutting are some techniques you may consider at this stage.

The sheet metal cutting technique should be accurate, cost-effective, and reliable. You will cut the sheet metal according to the mailbox design and dimensions in step 1.

Step 4: Sheet Metal Forming

During forming process, you will manipulate sheet metal according to the design in step 1. Depending on the design, you can use these sheet metal forming techniques:

  • Spinning – it makes axially symmetrical round metal mailboxes.
  • Bending – you can make many shapes including semi-circular sections or sharp bends. Again here, you can choose folding, V-bending, bottoming, coining, air bending, wipe bending, or rolling.

After forming all metal mailbox parts, it will be time to assemble the sections.

Step 5: Assemble Sheet Metal Mailbox Parts

For metal mailbox assembly, you will use:

  • Welding
  • Riveting
  • Mechanical assembly technique using bolts, nuts, and screws
  • Adhesive for metal

You will assemble the metal mailbox parts to form a complete part. The assembly mechanism should guarantee quality and secure sealing.

Lastly, you should subject the sheet metal mailbox to the necessary quality inspection. Then apply the necessary surface finishes.

Among the key surface finishes for sheet metal mailboxes include:

  • Polishing
  • Anodizing
  • Chrome plating
  • Brushing
  • Powder coating
  • Sandblasting, just to mention a few.

After applying the surface finish, check the metal letterbox quality.

Application of Sheet Metal Letter Boxes

As mentioned earlier, a mailbox acts as a temporary storage for letters. It keeps letters or mails safe before receiving or sending them to various destinations.

Of course, this applies to parcels or gifts. Ideally, you can install metal mailboxes in these areas:

  • Homes
  • Gardens
  • Post office
  • Schools
  • Commercial building
  • Residential buildings for tenants
  • Airports
  • Offices
  • Roadside
  • Stadiums, etc.

In short, you can install mailboxes anywhere, as long as the environment is safe and conducive. Of course, there must exist a framework for mail, or parcel delivery and collection.

Quick FAQs

Do Metal Mailboxes Rust?

Well, this depends on the metal type, surface treatment, and environment. However, you should note the following:

i. Stainless steel, galvanized steel, and aluminum exhibit excellent corrosion resistance properties. Therefore, using such material will prevent mailboxes from rusting.

ii. Powder coating or painting metal mailbox can prevent rusting

iii. Environments, where a metal mailbox is exposed to salty water, chlorine or any acidic moisture, may speed up the rusting process. Therefore, you must choose special metal grades such as stainless steel 310, and 316. Also, annealed aluminum alloy 5052 has excellent performance in seawater environments.

With all these considerations, you can prevent metal mailbox from rusting.

How Much Does Metal Mailbox Cost?

For wholesale, you can get mailboxes for as low as USD 3 to over USD 100. The metal mailbox prices are not fixed.

There are many factors determining sheet metal mailbox prices such as size, function, surface finishing, decorative requirements, and installation options, just to mention a few.

Mailbox suppliers from China offer competitive prices. You can count on KDMFAB when it comes to affordable metal mailboxes.

Can you Recommend the Best Paint for Metal Mailbox?

Well, there are many options available. However, from experience, enamel paints for metal guarantee better results.

You can spray paint metal mailboxes.

Are Metal Mailboxes Waterproof?


Metal mailboxes are fitted with rubber seals. Even the openings are specially designed to block dust, water, or moisture.

What is the Best Steel Gauge for Mailbox Fabrication?

About 10 gauge can serve you well. However, you can discuss this with the metal mailbox fabricator to choose an appropriate material.

How Safe is Metal Mailbox?

Here is a simple criterion on how to evaluate metal mailbox safety:

i. Use corrosion-resistant sheet metal such as aluminum, galvanized steel, or stainless steel.

ii. Choose the correct sheet metal gauge

iii. Ensure the design and material can withstand harsh weather conditions such as rain, moisture, fluctuating temperature, acidic environment,   salty water, dust, etc.

iv. Mailbox should have a locking mechanism

v. Where possible, you can incorporate a camera or alarm system. However, this feature may make metal mailboxes costlier.

vi. The joints and construction must be secure

vii. Anti-pry feature is another safety measure

viii. Latching mechanism will hold the door, hence your letters will be safe

Note: safety is only guaranteed when you work with a trusted and reliable mailbox supplier.


As you can see, there are many sheet metal mailboxes available in the market. From different sizes, configurations, and features to functionalities – you will find a mailbox that meets your specific needs.

At KDM, we fabricate metal mailboxes depending on our client’s specific needs. Contact us today for all your sheet metal letterboxes from China.

More Resources:

Types of Mailboxes – Source: Mail Box Works

Common Types of Mail Boxes – Source: KDM

Mail Boxes Types – Source: Angi

Mailbox Installation – Source: USPS

USPS Mailbox Regulations and Specification – Source: Mail Boxes

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