Full-Colour Personalised 375x255x150mm Mailer Boxes

Give your packaging the professional edge with our custom printed 375x255x150mm mailer boxes. These popular postal boxes are ideal for shipping clothing, gifts, eCommerce orders, and subscription sets, offering a secure, premium unboxing experience that keeps your products protected and your branding front and centre.

Manufactured from sturdy corrugated kraft board, these mailer boxes combine strength with a smooth surface that’s perfect for vibrant full-colour digital print. The triple-layer construction adds durability for dependable shipping, while the clean kraft finish ensures your packaging looks sharp and consistent across every order.

Each box is supplied flat-packed to save storage space and assembles quickly using strong folding tabs and flaps. Designed to qualify as a Royal Mail Small Parcel size, these mailer boxes help you avoid failed deliveries and keep postage costs predictable - making them a practical, brand-boosting solution for busy fulfilment environments.

• Vibrant full-colour print: Add your logo, artwork or message in crisp digital colour for instant brand recognition.
• Royal Mail Small Parcel friendly: The 375x255x150mm internal size is designed to fall within Royal Mail’s Small Parcel category.
• Strong mailer-style protection: Triple-layer corrugated kraft board gives reliable strength for posting a wide range of products.
• Professional unboxing feel: A smooth kraft surface and clean structure help elevate presentation for retail and subscription orders.
• Supplied flat-packed: Saves valuable storage space and keeps your packing area tidy.
• Quick, secure assembly: Folding tabs and flaps lock firmly into place for a tamper-resistant seal.
• Printed proof & satisfaction guarantee: Approve a full printed sample of your 375x255x150mm mailer box before full production.*
  *Please note this excludes printed single sample orders.
• Fast UK turnaround: Printed and delivered in as little as a few days to keep orders moving.
• UK made & printed: Manufactured and printed in the UK to reduce transport mileage and carbon footprint.
• FSC® certified materials: Produced using responsibly sourced board with 60%–90% recycled content.
• Size guide: Small parcel mailer postal box sizes (375x255x150mm) shown are the internal dimensions: Width x Depth x Height.

Considering a printed sample?

We offer an optional printed sample so you can confirm colour quality, print sharpness and suitability before ordering in larger quantities. When you proceed with a full order of the same design, we will refund the cost of the sample.

Please note: Minor branding or barcodes may appear on parts of the 375x255x150mm mailer boxes. Images shown are for guidance only and the supplied product may differ slightly.

Due to manufacturing tolerances, actual item dimensions may vary by 10–20mm. If sizing accuracy is essential, we recommend ordering a sample before placing a larger order.

Authentic Product Photography

All images displayed on Parcelsend UK represent genuine printed jobs we have produced. No visuals on this page are created or enhanced using AI - every photograph is taken from real customer orders to give you an honest representation of print quality and finish.

Because we use an on-demand, instant digital full-colour print system, we’re able to offer some of the lowest minimum order quantities in the UK - perfect for small runs or custom projects.

Please note: a one-time low-volume set-up fee of £49.95 applies to any order under £100. This is added automatically at checkout, but it won’t apply to repeat orders of the same product as long as the artwork remains unchanged.

All of our products are manufactured and dispatched right here in our own UK warehouse, which means we can offer some of the fastest turnaround times in the country. And because everything is produced in the UK (unlike many other providers), you’ll never have to worry about customs delays or surprise charges. Delivery is calculated at checkout based on order value - free over £70. All orders are shipped flat-packed for maximum efficiency.

100% Risk-Free Satisfaction Guarantee - We want you to feel totally confident when ordering with us. Before full production starts, you’ll get a proof (by app or email) and can make as many changes as you need until you’re completely happy. If you’d like to check our quality first, you can order a sample directly from the product page. Proofs aren’t provided with samples since they’re just for testing print and quality, but when you place your full order, you’ll be able to make amendments then. The cost of your sample will be refunded against your first full order*, and if you’re not happy with the quality, we’ll refund you in full.

*Sample refunds can’t be combined with other discounts or promotions.