Poly Mailer

What Is a Poly Mailer?

A poly mailer is a shipping envelope made from polyethylene plastic. It is lightweight, water-resistant and typically sealed with a self-adhesive strip. Poly mailers are widely used in ecommerce for soft goods that do not need crush protection, such as clothing, socks, swimwear and textiles. Some versions are padded, made with recycled content or printed with brand designs.

How It Works

The packer places the items, sometimes folded or in an inner bag, into a mailer sized to fit, removes excess air, seals the strip and applies the shipping label. Because mailers conform to the product's shape and weigh very little, the finished package is usually smaller and lighter than the same item in a box. Many mailers include a second adhesive strip so customers can reuse them for returns.

• Best for: apparel, socks, swimwear and other soft, non-fragile goods.
• Not ideal for: glass, liquids in fragile containers or items that crush easily.
• Options: plain, printed, padded or recycled-content mailers.

Why It Matters for Ecommerce Brands

Packaging choice affects both shipping cost and customer experience. Because carriers price on billable weight, which can be driven by package size, a compact mailer can lower postage compared with a box for the same item. Mailers also use less storage space in the warehouse.

For example, a streetwear brand shipping a single T-shirt can typically use a poly mailer rather than a small box, saving on packaging and potentially on postage. A brand that wants a stronger first impression might choose a custom-printed mailer. The key is matching the packaging to the product: poly mailers are excellent for soft goods but a poor choice for anything that can break or dent.