Letterbox friendly Boxes
Deliver your message in style with a custom letterbox, designed for mailing small items, promotional kits, or subscription packages. Lightweight yet durable, these boxes can be fully branded to reflect your identity and enhance the unboxing experience. Perfect for e-commerce, marketing, and direct mail campaigns.
Custom Letterbox Packaging for Smart, Stylish Shipping
Looking for a lightweight, cost-effective, and professional way to ship your products or promotional materials? Our Custom Letterboxes are designed to fit through standard mail slots while delivering a premium unboxing experience. Perfect for e-commerce, direct mail, brand kits, and subscription services, these boxes protect your products while promoting your brand in every delivery.
Geometric Adaptation Engineering — The Millimeter War of the Slot
The success of a letterbox box depends on absolute compliance with postal standards. If the thickness exceeds the limit by just 1mm, it shifts from a “Large Letter” to a “Parcel,” instantly doubling your shipping costs.
The 18mm – 24mm Golden Window: We utilize high-precision die-cutting to lock external thickness within postal limits.Yihong Box ensures your boxes pass through standard Royal Mail or European postal slots with a 99.9% probability, significantly optimizing your logistics ROI.
Anti-expansion Self-locking Structure: Traditional boxes tend to bulge in the middle once packed. We’ve developed “Inward-pressure Edges” that use physical tension to counteract expansion, ensuring the box remains horizontally flat throughout transit.
Flat Compression Mechanics — Preventing "The Door-slot Crush"
Letterbox boxes experience significant lateral squeezing when pushed through slots and lack cushioning upon hitting the floor.
ECT-32 Reinforced E-Flute: Despite the slim profile, we use high-density corrugated cores. The vertical Edge Crush Test (ECT) strength ensures that even at the bottom of a mail sack, the internal products remain in a zero-pressure vacuum zone.
Tamper-evident Full Sealing: Letterbox boxes typically require no tape. We utilize “Mechanical Friction Self-locking” generated by high-precision tolerances and one-time tear strips to provide physical-grade security without adding thickness.
Why Choose YiHongBox?
YiHongBox Box Packaging is your one-stop solution for fully customized packaging—offering end-to-end services to bring your unique packaging vision to life.
Structural Design Support
From concept to prototype
Premium Print Quality
Certified equipment, precise color
Sustainable Materials
FSC, Soy Ink, Recyclable Paper
Fast Sampling & Delivery
Samples in as fast as 7 days
Frequently Asked Question
A custom letterbox is a slim, lightweight box designed to fit through standard postal slots. Unlike regular boxes, it minimizes shipping costs and avoids missed deliveries, making it ideal for e-commerce, sample kits, and direct mail campaigns.
Our standard MOQ for corporate gift boxes starts at 500 units. Bulk orders benefit from tiered pricing.
Lead time typically ranges from 10–15 business days after artwork approval. Urgent orders can be expedited upon request.
Since external space is restricted, we recommend “Inward Narrative.” By applying full-color printing to the interior of the Yihong Box, the visual impact explodes the moment the consumer lifts the lid. This “Cold Outside, Warm Inside” design maximizes brand loyalty without violating postal regulations.
Yes! We offer fully customizable letter box packaging — including size, material, printing (inside and outside), finishes, inserts, and structural design. Share your product dimensions and branding needs, and we’ll handle the rest.
Most of our custom letterboxes are made from durable corrugated cardboard or eco-friendly kraft board. They’re strong enough to protect contents during shipping while remaining lightweight for cost efficiency.
Absolutely. Our boxes are built for strength and postal compatibility, making them perfect for international shipping. We also ensure sizes meet various country mail slot standards when needed.
We’ve eliminated all unnecessary plastic lamination. We use 2026-grade Aqueous Coating for moisture resistance and luster. This ensures the entire letterbox box is 100% mono-material paper-based and curbside recyclable, fully complying with 2026 sustainability audit standards.
Rigid
A thick and sturdy chipboard known for its premium quality and durability. It is used for luxury packaging and high-end product displays
Cardboard
A durable and lightweight paperboard material. It can have a clay-coated surface on one or both sides for enhanced printability.
Corrugated
A strong and lightweight material with a fluted inner layer for added durability and cushioning. Perfect for shipping and product protection.
Kraft
A strong, eco-friendly, unbleached kraft paperboard made from wood pulp. It has a natural brown color, making it ideal for sustainable packaging.
Aqueous
Water-based coating offers environmental friendliness and fast drying.
Glossy
A shiny and vibrant finish thatenhances color depth andcontrast,making designs pop.
Soft-Touch
A velvety, premium finish that
adds a luxurious feel while
providing a subtle matte
appearance.
Matte
A highly reflective coating gives a shiny, polished appearance.
Hot Foil Stamping
Form of relief printing in which foil is transferred to a surface at high temperatures.
Embossing
Creates a raised, textured effect on paper or cardstock.
Debossing
Creates a depressed, indented effect on paper or cardstock.
Window Patching
Die-cut shape is layered with plastic film to feature a window showcasing the product inside.
