What Are Do Not Bend Envelopes and When Should You Use Them?
Everything you need to know about do not bend envelopes and when they are the right choice.
What are do not bend envelopes?
Do not bend envelopes (also called board-backed envelopes or hard-backed envelopes) are mailing envelopes with a rigid board backing that prevents the contents from bending during postal handling. They typically have a paper front, a board back, and a peel-and-seal closure with "DO NOT BEND" printed on the exterior.
Quick answer
Do not bend envelopes are board-backed mailing envelopes designed to protect flat items from bending in the post. Use them for art prints, photographs, certificates, legal documents, and any flat item that must arrive uncreased. Available in C5 (A5), C4 (A4), and C3 (A3) sizes. Board weight ranges from 350gsm for basic protection to 700gsm+ for maximum rigidity. C4 and C5 sizes qualify for Royal Mail large letter rates.
How do they work?
A rigid board insert prevents the envelope from flexing during sorting and delivery.
Printed instructions alert postal workers to handle with care.
The closure bonds firmly and shows evidence if opened.
When to use them
Use do not bend envelopes for0 / 6 checked
Get started: size and material guide or Royal Mail guidelines.
Sizes and options
Do not bend envelopes
Board-backed envelopes in every size from ProcuraPack.
Browse do not bend envelopesFrequently asked questions
Board-backed envelopes with rigid backing that prevents contents from bending in the post.
For any flat item that must arrive uncreased: prints, certificates, legal documents, invitations.
C5 (A5), C4 (A4), and C3 (A3). C4 is the most popular.
C4 and C5 can if under 25mm thick and 750g. C3 ships as small parcel.
350-400gsm for documents. 500-600gsm for prints. 700gsm+ for fine art.
Part of our guide
Product Guide: Do Not Bend Envelopes
Expert guides on rigid mailers and board-backed envelopes for protecting documents, prints, and certificates.
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