Board Backed Envelopes

Board backed envelopes for UK sellers posting anything that must arrive flat. Also called hard backed envelopes, card backed envelopes, cardboard backed envelopes, board back envelopes or simply do not bend mailers. Supplied in trade packs, brown or white, C6 through to C3.

One job, done properly: the contents do not bend

A board backed envelope is a paper envelope with a rigid board panel laminated to one face. That's it. The paper carries the address and the seal; the board carries the load.

It matters because bending is the failure mode that ordinary mailers ignore. A photograph, a certificate or a signed print doesn't get damaged by being dropped — it gets damaged by being rolled through a sorting machine, pushed through a letterbox, or wedged into a full post bag. Padding does nothing about any of those. Rigidity does.

The board goes on one face rather than both, which keeps the weight and the thickness down. That's deliberate: two boards would be marginally stiffer and would cost you a postage band.

Who buys these, and what they're protecting

Photographers and print sellers. The largest single group. A print that arrives with a crease across one corner is a full refund plus a reprint, and the envelope costs a fraction of either.

Framing shops, galleries and artists posting unframed work.

Registrars, schools, awarding bodies and HR departments sending certificates, transcripts and formal documents that cannot be creased.

eBay, Etsy and Discogs sellers shipping trading cards, comics, postcards, memorabilia and ephemera.

Anyone posting anything signed. Autographs, limited editions, artist proofs — items where condition is most of the value.

Choosing a size

Sizes run from C6 up to C3, and the sizing logic is simpler than it looks: match the envelope to the paper, then check it isn't generous.

C5 takes A5 flat or A4 folded once. C4 takes A4 flat — the common choice for certificates and documents. C3 takes A3 flat, or A2 folded, which is where most print sellers land. C6 suits cards, photographs and small ephemera.

Snug beats roomy here. A rigid envelope only protects what it holds still. Contents that can slide inside a generously sized envelope will find the unsupported edge, and the board can't help them there. If you're between sizes, take the smaller one and check it seals flat.

Brown or white

Both are stocked in the middle sizes. The board and the protection are identical; the difference is presentation.

Brown kraft reads as trade and unfussy, and it hides handling marks well.

White reads as considered, photographs better for social content, and takes a printed label or a stamp more cleanly. If the envelope is part of what the customer is paying for — a print, a piece of art, anything gifted — white generally earns its small premium.

Postage: what "do not bend" costs you

Board backed envelopes are thin, which is the point. A C4 with a few sheets inside sits comfortably inside Royal Mail's Large Letter band, and that's the cheapest way to post something flat and rigid.

Two things will push you out of the band. Depth over 25mm, which is hard to reach with a board backed envelope unless you overfill it. And weight over 750g, which a C3 with several prints inside can reach more easily than people expect.

Weigh a packed sample before you standardise. Carrier bands are revised, and the gap between Large Letter and Small Parcel across a year of orders is worth knowing precisely rather than approximately.

Printing and bespoke

The face of a board backed envelope is a large, flat, clean surface — one of the better printing areas in postal packaging, and mostly wasted. Printed envelopes get recognised in a stack of post, and for anyone whose product is visual the outer packaging is the first thing the customer sees.

We quote on printed and bespoke work as part of a manufacturing group. Tell us the size, the finish and the volume and we'll come back with options.

Buying by the pack

Supplied in trade packs, with price breaks as quantities increase. Pack quantities differ between sizes, so compare the per-envelope price in the table rather than the pack price — a larger size can show a lower pack price simply because the pack is smaller.

We buy these as part of a manufacturing group, at volumes a reseller can't reach, and hold them across over 100,000 square feet of warehousing — so the size you standardise on is the size that's still there next month.

Delivery and returns

Order by 2pm, Monday to Friday, for same-day dispatch. Free UK mainland delivery in 1–2 working days, with a £75 minimum order. Full terms on our delivery and returns pages.