Rigid Stay Flat Mailers — Cardboard Boxes

You can purchase small rigid mailer boxes directly through Cardboard Boxes 4U online. Small sizes start at 9-1/4"x3"x6-3/4" for side-loading styles and 7"x7"x3" for flat corrugated boxes. Orders can be placed via the online cart, and account creation enables order tracking and shipping status monitoring.

A rigid cardboard mailer is a corrugated box designed to remain flat and stiff during shipping, preventing bending or crushing of contents. Unlike padded envelopes, rigid mailers use single or double-wall corrugated cardboard construction — offering structured protection for items like artwork, books, documents, mirrors, and framed goods.

Single-wall corrugated mailers use one fluted medium between two liners, suitable for lighter flat items like apparel or documents. Double-wall construction adds an extra fluted layer, providing up to 275# burst strength for heavier or more fragile items such as mirrors, framed artwork, and glass. Choose based on product weight and fragility.

Yes. Cardboard Boxes 4U offers full-color custom printed corrugated mailers for branded packaging. Custom options are available for both side-loading and flat box styles. These are ideal for e-commerce businesses seeking a professional unboxing experience. Contact the team directly or use the online ordering system to initiate a custom print order.

Yes. All corrugated cardboard mailers from Cardboard Boxes 4U are recyclable. Corrugated packaging is one of the most widely recycled materials in the U.S. The boxes ship flat to reduce storage space and transportation costs, further supporting a lower environmental footprint across your fulfillment and distribution operations.

Side-loading rigid mailers are available with three closure types: Full Overlap (FOL) for maximum seal security, Self-Seal for convenient peel-and-stick closure without tape, and Locking Mailer style for tamper-resistant shipping. Each closure type suits different fulfillment speeds, security needs, and product types across e-commerce and retail applications.