Heavy Duty Envelopes / Cardboard Envelopes


Our Heavy Duty Cardboard Envelopes are a premium protective box mailers for those requiring the highest degree of protection for items sent in the mail. Manufactured from corrugated board, our heavy duty envelopes are the strongest envelope mailer postal product on the market.

These strong, carton envelopes offer huge savings on postage, where the required sized allows posting as a large letter, rather than a packet or parcel under Royal Mail Pricing in Proportion guidelines. Such as with the C4 size mailers listed here for A4 sized items.

Our cardboard envelopes and box mailers can be produced in sizes to suit the individual needs of customers’. For example C3 size (for holding A3 sized documents and objects) , C4 (for holding A4 Sizes documents and objects) etc.

Various closure options available depending on a customer's requirements: lock-tabs, glued or peel and seal. For bespoke designs for either closure style or mailer size will require minimum order quantities.

Need more information about heavy duty envelopes or packaging in general? Feel free to get in touch on 02476 422000 - we would be delighted to discuss your requirements.

Samples of C4 / A4 sizes & C3 / A3 Sizes of our strong envelopes are available on request.

Many customers purchasing carboard envelopes also invest in Custom Printed Tape to add customised branding to their packaging.

Below are the two main types of strong envelope that we stock:

C3 / A3 RoMaPro Ultimate Mailers 462mm x 330mm (18

A3 / C3 ParcelMax Mailer / Heavy Duty Envelopes