Mailing Boxes & Cartons
A complete range of cardboard postal boxes and cartons for posting parcels safely. Choose by Royal Mail size to keep your postage costs down, or by box type for books, bottles, frames and more.
Shop boxes by type
- Royal Mail Large Letter Size Boxes
- Royal Mail Small Parcel Size Boxes
- Royal Mail Medium Parcel Size Boxes
- Single Wall Cardboard Boxes
- Double Wall Cardboard Boxes
- Brown Postal Cardboard Boxes
- White Postal Cardboard Boxes
- Premium Postal Cardboard Boxes
- E-commerce Boxes
- Book Wrap Mailers
- Capacity Book Mailers
- Cardboard Envelopes
- Corrugated Pocket Boxes
- Pizza Boxes
- Picture Frame Boxes
- Pillow Boxes
- Telescopic Boxes
- Wine Bottle Boxes
Why buy from Mailcoms
Mailcoms is a trusted UK mailroom supplier, trading since 2005, with fast delivery and free UK delivery over £40.
Frequently asked questions
How do I choose the right box size for Royal Mail?
Match the box to the Royal Mail Large Letter, Small Parcel or Medium Parcel dimensions for the cheapest postage - we group boxes by these sizes.
What is the difference between single and double wall?
Double wall boxes have an extra layer of corrugated board for heavier or more fragile items, while single wall suits everyday parcels.
How fast is delivery?
Standard UK delivery is 3-5 working days and free on orders over £40, with a next working day option available.