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Letterbox Boxes
Letterbox boxes are designed to fit through a standard UK letterbox — no missed deliveries, no redelivery cards, no customer waiting in for a knock that never comes. For ecommerce businesses despatching smaller products, it's a simple change that makes a real difference to both delivery success rates and customer experience.
Our range is Royal Mail compliant, meeting large letter and small parcel size specifications, so you can keep postage costs low while still getting a proper protective box rather than a padded envelope. All made from FSC-certified corrugated cardboard, 100% plastic free, and fully recyclable.
When are letterbox boxes the right choice?
Letterbox boxes work best for products that are compact and relatively flat — cosmetics, jewellery, small gifts, vouchers, product samples, greeting cards with inserts, and subscription box items. They offer more depth and rigidity than a cardboard envelope, which means better protection for anything fragile, while still being slim enough to post without a signature.
If your product doesn't quite fit a letterbox format, our postal boxes cover a wider range of sizes while still being optimised for low-cost shipping.
Letterbox boxes and Royal Mail sizing
To qualify as a large letter — Royal Mail's most cost-effective size band for boxed items — your packed box must be no larger than 353mm × 250mm × 25mm and weigh no more than 100g. Our letterbox box range is sized to sit within these thresholds, but it's worth double-checking your packed dimensions before committing to a size. Our Royal Mail size guide sets out all the thresholds clearly.
Sending flowers through the letterbox? Our flower boxes include letterbox-friendly options specifically designed for fresh stem delivery.
For a full guide to cardboard box types and postal sizing, see our complete guide to cardboard boxes. Or browse the full range if you need something beyond letterbox packaging.
