Cardboard Shipping Mailers & Envelopes

Rigid mailers are generally not classified as standard envelopes by carriers like USPS because they do not bend to pass the flexibility test. They are typically rated as packages or flats, which affects postage pricing. Always check with your specific carrier to confirm how rigid cardboard mailers will be categorized and priced before shipping.

Yes, documents can be sent in a bubble mailer. Bubble mailers provide lightweight cushioning that protects papers from bending, moisture, and minor impacts during transit. They are commonly used for sending contracts, certificates, photos, and other important documents. For added rigidity and protection, a flat corrugated cardboard mailer may offer superior stiffness and crush resistance.

Thin pieces of cardboard, such as backing boards or flat corrugated sheets, can be mailed inside a standard envelope if they fit within carrier size and thickness requirements. However, for structured corrugated cardboard mailers, they are shipped as packages or flats. Always verify dimensional and weight limits with your carrier before mailing cardboard items.

Our corrugated mailers range from as small as 9¼" x 3" x 6¾" up to 56" x 10" x 32", covering 22 SKUs. This wide size range accommodates everything from small e-commerce items to large flat products like mirrors, picture frames, and artwork. Custom sizes are also available on request for specific applications.

Our cardboard mailers are available with several closure options: Full Overlap (FOL) for maximum stacking strength, self-seal adhesive strips for fast and secure closure without tape, and locking mailer designs for tamper-resistant shipping. The right closure type depends on your product weight, shipping method, and the level of security or speed required in your fulfillment process.

Yes, Cardboard Boxes 4U offers full-color custom-printed corrugated mailers for branded packaging. Custom printing is ideal for e-commerce brands looking to create a strong unboxing experience. Orders can be placed online, and our team can assist with design specifications. Both white and kraft corrugated substrates are available for custom print runs.