Aluminium vs. Steel: A Specifier’s Guide to Mailbox Longevity and Security
Selecting the right mailbox system goes far beyond comparing prices or aesthetic details—it’s a critical decision that influences security, compliance, and long-term maintenance requirements.
The choice between aluminium and steel should be guided by factors such as environment, durability, longevity, and visual preference.
Aluminium is frequently specified for its exceptional strength‑to‑weight ratio, high corrosion resistance, and its ability to be infinitely recycled without losing quality—resulting in long‑lasting, low‑maintenance solutions for construction projects.
At The Safety Letterbox Company, we manufacture both materials. Our market‑leading Steel 1, 2, and 3 ranges offer excellent performance, while our COM 1, 2, and 3 aluminium post box systems are considered the “Gold Standard” for durability and security, with both ranges fully conforming to EN 13724 and Class 0.
Aluminium Series
Steel Series
| Feature | Aluminium Series Post Boxes (COM 1, 2, 3) | Steel Series Post Boxes (Steel 1, 2, 3) |
| Best For | External, Coastal, & High-Risk Areas | Internal Lobbies & Controlled Access |
| Construction | Fully Welded Heavy-Duty Extrusion | Precision Folded Sheet Steel |
| Security Level | Ultra-High (Anti-Fishing & Anti-Lever) | High (Market-leading standard) |
| Durability | Naturally Corrosion Resistant | High (Internal) / Cladding Required (External) |
| Finish | Full RAL Powder Coating | Full RAL Powder Coating |
| Compliance | Conforms to EN13724 & Class O | Conforms to EN13724 & Class O |
| Weight | 1/3 of the weight of Steel – while still remaining strong | Heavier, weightier product |
Key Differences Between Aluminium and Steel Mailboxes
1. Engineering Strength: Welded vs. Folded
The primary differentiator between our ranges is the fabrication method.
– The Aluminium Advantage: Our COM mailbox range is constructed from heavy-duty aluminium extrusions that are fully welded. This creates a monolithic, seamless frame. In high-traffic or unsupervised areas, this rigid structure is highly resistant to manual levering and tampering.
– The Steel Standard: Our Steel post box range is precision-folded. This provides a robust and cost-effective solution for secure internal use.
2. Advanced Security Features
Security is a core priority for modern developments. Because of the way our aluminium profiles are extruded, we can build high-performance security features directly into the profile that are not possible with folded steel:
– Integrated Security Bridge: A physical reinforced extrusion to protect the most vulnerable pray-points of the mailbox.
– Fur-Lined Apertures: Beyond aesthetics, the fur trim acts as a sophisticated weather protection while ensuring a smooth, high quality, quiet user post box experience.
3. Environmental Suitability & Compliance
Specifying the wrong material for the environment is a common cause of premature product failure.
– Aluminium Mailboxes (Internal & External): Aluminium is naturally resistant to oxidation. This makes it the only choice for external walls, perimeter fences, or developments in coastal areas where salt spray would compromise other materials.
– Steel Post boxes (Internal Only): Our steel products offer exceptional longevity indoors. However, they are advised for internal use unless specified with additional weather cladding. For Architects, specifying aluminium for external use removes the risk of future aesthetic degradation.
4. Aesthetics and Lifecycle Value
Both materials undergo finishing in our state-of-the-art powder coating facility and can be supplied in any RAL colour to suit your project’s branding. Our three stage pre treatment process is key to achieving exceptional powder adhesion, ensuring long-lasting performance with no fading, chipping, or flaking over time.
While Aluminium carries a higher upfront procurement cost, it often delivers a lower Total Cost of Ownership. Its resistance to corrosion and enhanced security features result in a long replacement cycle, and a better long-term experience for residents.
Specifier’s Post Box Quick-Reference:
Myths vs. Reality
❌ Myth: “Steel is always stronger than aluminium.”
✅ Reality: Not in mailbox construction. A welded aluminium extrusion is the ultimate product due to it’s durability and strength.
❌ Myth: “Steel is fine for external use if it’s powder-coated.”
✅ Reality: Powder coating is a finish, not a total barrier. Without additional cladding, steel will eventually succumb to edge-corrosion outdoors. Aluminium is the professional standard for external durability.
❌ Myth: “Both materials offer the same security.”
✅ Reality: Aluminium extrusion allows for integrated anti-fishing bridges and fur-lined apertures—features that significantly elevates the security grade.
Recommendations by Project Type
For National House Builders
Use Aluminium post boxes for external entrance points and communal areas to reduce long-term warranty claims.
For Architects
Specify Aluminium mailboxes for contemporary schemes where clean, welded lines and maximum security are required.
For Interior Designers
Steel post boxes offers a high-value, aesthetically versatile solution for secure, internal locations.
Choose the Right Specification for Your Next Project
With over 40 years of expertise, The Safety Letterbox Company helps you balance budget, aesthetics, and security.
Speak with the team today or download a copy of our full technical data sheets for the COM mailboxes and Steel post box ranges to assist with your current specification.
