A packing bench at the end of a busy day: a stack of T-shirts, a few paperbacks, a phone case, a bottle of serum and a ceramic mug. Which of those can go in a poly mailer? Most of them. The mug cannot, and the serum needs more thought. Getting this sorting right is how a shop cuts postage and packaging cost without a rise in damaged parcels.
This follows on from Part 1 of our poly mailer guide, which covered why and when to use mailers. Here the focus is what goes inside them and how to buy them in volume.
The sorting-cage test
Imagine the parcel at the bottom of a sorting cage with heavier boxes landing on top. If the item would come out fine, a mailer will do. If it could crack, bend, leak or crumble, use a carton, or put the item in its own rigid box before it goes in the mailer.
Product by product
| Product | Mailer? | Best option |
|---|---|---|
| T-shirts, jeans, knitwear, sportswear, underwear | Yes | Standard mailer |
| Hoodies, jackets, shoes in a shoe box | Yes | Large or gusseted mailer |
| Bed linen, towels, scarves, yarn, craft fabric | Yes | Standard mailer sized to the folded item |
| Paperbacks and catalogues | Yes | Bubble-lined, or standard with a card stiffener |
| Art prints and photos | With care | Mailer plus rigid backing board |
| Lipstick, tubes, sealed supplement pouches | Yes | Bubble-lined mailer |
| Phone cases, card games, boxed stationery, plush toys | Yes | Standard or bubble-lined |
| Liquids in thin bottles, anything in glass | No | Box with cushioning |
| Ceramics, mirrors, unboxed electronics or sunglasses | No | Box with cushioning |
| Biscuits, chips, cakes | No | Box |
Two more cases to keep out of mailers: items with sharp corners that can punch through the film, and structured garments such as hats that lose their shape when squeezed.
The four mailer types in brief
Standard mailers are single-layer or co-extruded polyethylene with a peel-and-seal strip. They are the lightest and cheapest option, and waterproof. White-outside, black-inside co-extruded film stops anyone seeing what is in the parcel.
Bubble-lined mailers add a layer of bubble film inside the poly outer. They protect against scuffs and light knocks and still weigh far less than a box.
Gusseted mailers open out at the sides or base for bulky items. They are often made thicker for better puncture and tear resistance.
Recycled-content mailers use a share of recycled polyethylene, and some brands choose compostable films. Check which environmental claims are allowed in your market and ask your supplier for documents that back them up.
Specifying mailers for a wholesale order
- Sizes: choose a small set of sizes that covers most of your range, so items fit snugly and you are not paying to ship air.
- Thickness: go thicker for heavy or angular items; light apparel can use a thinner gauge.
- Film: most mailers are LDPE or LLDPE blends for stretch and toughness. Ask what the blend is and how much recycled content it contains.
- Closure: a permanent adhesive shows tampering; a second strip lets customers reuse the mailer for returns.
- Print: a logo on every parcel is free advertising on the doorstep. See our private label and custom printing options.
- Packing: agree how many mailers go in each carton and what goes on the carton label.
Items that need to stay clean or grouped before mailing can go into flat poly bags or zipper bags first.
On the buying side, Hanpak quotes MOQ per size and design, so a short run of one size is possible alongside a larger run of another. Lead time is 4–6 weeks for a first order and 3–4 weeks for repeats, counted from sample approval. Every pack carries a lot number, and production photos are sent while the order runs.
A useful check on samples is to fill a mailer with your heaviest or most angular product, seal it and drop it on a corner. Then look at the adhesive strip and the bottom seal, because those fail first. If the seal lifts, we usually suggest a wider adhesive strip or a longer flap before moving up to a thicker film.
From the Hanpak team
Ready to price your mailers?
Hanpak supplies plain and custom-printed poly mailer bags for e-commerce brands, distributors and fulfilment centres. Send your sizes, quantities and artwork to request a quote or samples on our contact page or via WhatsApp. Stock samples are free.