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Home > Guides > Shipping in a poly mailer
A poly mailer suits soft, light, non-fragile items that can handle a squeeze: clothing, plush toys, fabric, and soft accessories. Anything rigid, sharp, or breakable belongs in a box instead, because a mailer gives almost no crush protection and a sharp edge will poke straight through it.
| Item | Mailer or box? | Why |
|---|---|---|
| T-shirts, scarves, fabric | Mailer | Soft, light, no breakable parts |
| Plush toy | Mailer, in a bag | Soft, but needs damp protection |
| Book, DVD case, framed print | Box | Corners and edges crush in a mailer |
| Anything sharp or heavy | Box | Punctures mailers and tears seams |
| Cosmetics in jars | Box | Glass and leaks need rigid packing |
Padded mailers, lined with bubble wrap, suit items that need a little cushioning, like a folded sweater or a soft toy. Plain unpadded mailers suit tough fabric items that cannot break, like a scarf or a tea towel. The mailer should fit the item with a little room to spare: too tight, and the seam strains when you seal it; too loose, and the item slides around and the empty flap bunches up. Fold excess material neatly rather than leaving a long loose tail.
Check the mailer before you use it. A mailer with a torn corner, a weak seal strip, or a previous label that will not peel off cleanly is not worth the risk. The seal strip is the mailer's main closure, so press it firmly along its full length, then add a strip of packing tape across the flap for parcels that will travel far. That extra tape stops the flap lifting in sorting machines.
Stick the label on the smoothest, flattest part of the mailer, away from seams and folds. A label wrapped around a curve or creased over a seam can crack and become hard to scan. Keep tape off the barcode itself: tape over a barcode can glare under a scanner and slow the parcel down. If the mailer surface is textured or dusty, wipe it first so the label sticks flat.
Write the return address on the mailer as well as on the label, in case the label peels off. Poly mailers are smooth, which helps labels stick, but that same smoothness means a loose label has nothing to grip. A second copy of the address inside the mailer, on a slip of paper, is cheap backup for a valuable parcel.
A mailer will not protect against crushing, bending, or punctures. A book shipped in a mailer often arrives with bent corners, because other parcels press on it in transit. A rigid item, like a phone case or a small electronic gadget, can crack a mailer seam from the inside when the parcel is stacked. When the item has any hard edge, a box with padding is the honest choice, even if a mailer would be cheaper.
Mailers do have real advantages: they weigh almost nothing, they resist rain better than plain cardboard, and they take less space in a mail bag. For the right item, that makes them the sensible pick. If the parcel stays within Canada and under 5 kg, you can get a Canada Post Xpresspost label by asking your AI assistant: you approve the exact quoted price, pay once through Stripe, and get a label PDF to print and attach.
Yes, if it is still strong: no tears, a working seal, and no old labels or barcodes left on it. Peel off every old label, or cover old barcodes completely with opaque tape or a blank label, so a scanner does not read the wrong code. If the seal strip is spent, tape the flap shut fully. Retire any mailer that is stretched thin, torn at the corners, or printed with a previous address that cannot be covered.
Ready to ship it? Get a shipping label with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and get your label.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
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