Design online
100% recyclable
Free UK delivery
Letterbox Friendly
Minimum order quantity: 100
Fully customisable, mailer boxes are ideal for shipping everything from clothing to cosmetics. They’re also FSC-certified and 100% recyclable, making them perfect for businesses looking for more sustainable packaging boxes. Extra features allow you to create a seamless unboxing experience.
- E-commerce
- Retail
Have questions? Contact us
How it works
Carbon footprint
See how the carbon footprint of Sourceful’s mailer box compares to a benchmark product.
Reduce your carbon footprint by up to 12%
-8% CO2e
Custom sizing
Create custom-sized packaging online with Sourceful. Eliminate waste and reduce your carbon footprint. By reducing void space to half the industry average, you can reduce your total order carbon footprint by up to 8%.
-4% CO2e
Sampling
Visualise and proof your packaging online in Sourceful’s Design Studio and remove the need to order samples. By not sampling you could reduce your total order carbon footprint by up to 4%.
Specification
Understand your entire supply chain
- F0
FEFCO 0427
Quick to assemble, FEFCO 0427 has a wide, flat interior surface which is ideal for branding or creating a memorable unboxing experience. FEFCO 0427 is durable in transit with each sidewall constructed from two layers of cardboard, providing excellent crush resistance. - Bk
Brown kraft
FSC-certified, unbleached and uncoated paper made from virgin pulp. Brown kraft is the most sustainable material for these mailer boxes. - Wc
White coated
FSC certified, bleached paper made from recycled and virgin pulp. Coated with kaolin clay to create a smooth surface for printing with a shine.. - Bt
Brown testliner
FSC certified and made from 100% recycled fibres, brown testliner is a cost-effective paper used on any non-printed, brown side of a mailer box. This reduces its carbon footprint and cost. Testliner isn’t printed on as colours can appear muted and finer details can occasionally blur because of its high absorption rate. - Wt
White testliner
FSC certified and made from 100% recycled fibres, white testliner is a cost-effective paper used on any non-printed, white side of a mailer box. This reduces its carbon footprint and cost. Testliner isn’t printed on as colours can appear muted and finer details can occasionally blur because of its high absorption rate. - E
E-flute
E-Flute (1.5-2.0mm) is used for all Sourceful mailer boxes. It has great crush resistance for its weight, provides a flat surface for printing and is easy to fold. - Vi
Vegetable-based inks
Made with vegetable oils as their primary base, these inks are designed for high-quality offset printing. More sustainable than solvent-based inks. - Ws
Water-based sealant
Applied to every printed side of a mailer box. This is a standard part of the offset printing process to ensure colour consistency and avoid scuffing. Does not impact the recyclability of the box. - Uv
UV varnish
Used to highlight printed features or create a high gloss, professional finish over an entire print area. UV varnish also protects colours and reduces the risk of colours running when wet. Mailer boxes with a UV varnish are widely recyclable. - Sp
Single peel & seal
One strip of adhesive covered with a fibre-based backing paper. A single peel & seal makes fulfilment fast and helps make your packaging tamper-proof. Adding a peel & seal has minimal impact on your carbon footprint. - Dp
Double peel & seal
Two strips of adhesive covered with PET backing paper. A double peel & seal makes fulfilment fast and returns easy for your customers. Adding a peel & seal has minimal impact on your carbon footprint.
Supply chain assurance
A resilient, responsible supply chain
Certifications
Vetted suppliers
Quality control
FAQs
A mailer box is a corrugated box that's usually used for e-commerce. They're ideal for sending all kinds of products and they're one of the most sustainable types of packaging. You also don't need glue or tape to assemble them.
It depends on the size of your product and how you're shipping it to your customers. Use the internal dimensions of a mailer box to work out if your product will fit inside. Then use external dimensions to request shipping quotes and check if it meets any size restrictions.
Standard UK letterboxes measure roughly between 200-250mm x 35-40mm. We recommend internal dimensions of 195mm x 30mm when creating a custom-sized mailer box to ensure this will fit.
It depends on the material you choose, the size of your mailer box, how it's packed and how it's been stored. Incorrect storage, for example, can lead to mailer boxes becoming weaker over time.
We don't recommend sending anything heavier than 2kg in a mailer box, but because there are so many variables, we can't guarantee that every mailer box will safely hold this weight. Our recommendation also matches Royal Mail's Small Parcel weight limit.
If you want to send something heavier, we recommend a Shipping Box.
Yes! Sourceful mailer boxes are more than durable enough to ship products internationally, although we can't guarantee the condition of a mailer box after transit.
As always, they should be packed to at least 80% capacity to minimise the impact of any bumps in transit. Fragile items should also have added protection, such as void fill or a thicker flute profile. Have questions? Contact us
A peel & seal (a built-in self-adhesive strip) is the easiest and fastest way to seal a mailer box. You can add one during configuration. Other options include stickers or gummed tape, which you can brand as well.
Inserts aren't available in the shop yet, but they will be soon. In the meantime, we handle custom inserts as an RFQ. Contact us
Store your mailer boxes in a dry environment, away from possible sources of moisture like rain, leaks or areas of high humidity. You should also store them at a relatively constant temperature. Learn more
Yes! Your mailer boxes will arrive pre-creased, and you can assemble them easily by hand without glue or tape.
If you create a custom-sized mailer box with a depth less than 35mm, some sides may be harder to fold. Double-sided printing will increase this risk because of the extra material involved.