A mailer box is a one-piece corrugated box that folds up from a flat die-cut sheet. The lid is hinged at the back, the side walls roll over and lock, and the front panel tucks in to close. It needs no tape or glue, and it is strong enough to send many products direct to a customer, which is why ecommerce brands, subscription boxes and PR kits use it so often. The industry name for the structure is a roll-end tuck-front (RETF) mailer.
To see our samples or ask for a quote, go to the custom mailer box page.
How a mailer box is built
The flat blank has a base panel, a front panel, two side panels with double walls, a back panel and a lid with a tuck flap. When you fold it, the side walls roll inward over small dust flaps and lock into slots in the base. The lid then closes over the top and its tuck flap slides in behind the front panel.
The double side walls make the box stiffer than a single-wall carton of the same board. The rolled edges also hide the cut edge of the corrugated board, so the box looks finished inside and out.
How to measure for a mailer box
Mailer sizes are given as length × width × depth. Length and width are the base of the box, with length as the longer side. Depth is the height from the base to the closed lid.
Measure the product, or the packed set, at its widest points. Then add room for whatever goes in with it: tissue, a card, a booklet, an insert or cushioning. Tell us whether your figures are internal or external dimensions. Corrugated board is thicker than paperboard, so the difference between the two can be several millimetres on each side.
Keep the fit snug. A product that slides around inside a mailer is more likely to be damaged in transit, and an oversized box costs more to ship. If you sell several products in different sizes, ask whether one or two mailer sizes with different inserts could cover the range.
Choosing the corrugated board
Corrugated board has a fluted middle layer between two flat liners. Flute size is the main choice. A fine flute, such as E-flute, gives a thin wall and a smooth surface for printing, and suits small, light products. A larger flute, such as B-flute, gives a thicker wall and more cushioning for heavier items. We recommend a board in the quotation based on your product weight, box size and shipping route, and you test it on the sample.
The outer liner can be white or natural brown kraft. White gives brighter print colors. Kraft gives a natural look, and printed colors on it appear darker.
Printing inside and outside
A mailer can be printed on the outside, the inside, or both. Outside printing carries the brand through the delivery network. Inside printing is what the customer sees when the lid opens, and many brands put a message, a pattern or a thank-you note there. Inside printing adds a production step, so tell us when you request a quote if you want it.
We print by offset printing and can add hot foil stamping, embossing, debossing, UV coating and lamination where the board allows. See packaging printing and finishing for how each effect works. Put your artwork on our dieline and check the orientation of every panel, especially the lid and front panel, which face opposite ways on the flat sheet.
Inserts
An insert holds the product in place and keeps it off the walls of the box. It can be a simple card divider, a shaped cut-out or a raised platform for presentation. For sets, the insert also decides the order in which the customer sees each item. Send the dimensions of every item and a note on how you want them laid out.
Can a mailer box ship without an outer carton?
Many mailer boxes ship on their own with a shipping label on the lid. Whether yours can depends on the product weight, how fragile it is, the board you choose and the delivery route. A glass bottle sent by parcel post needs more protection than a T-shirt. Test the approved sample with the real contents before you decide. For heavy or fragile items, you may need an insert, extra cushioning or an outer shipping carton.
If the product sits in its own retail box inside the mailer, compare a printed folding carton for the inner box.
What to check on the sample
- Fold the box from flat and close it. The side walls should lock without tearing, and the lid should tuck in cleanly.
- Pack the real product with any tissue or insert and check the fit.
- Look at print color and registration on the outside and inside.
- Shake the closed box gently and listen for movement.
- If you can, send the sample through your usual courier and check how it arrives.
Sampling takes 7 days after the specification is confirmed. We adjust the sample if needed, and production starts after you approve the sample and the final artwork.
Ordering and what to send
The minimum order is 500 pieces per design. Production takes 21 days after sample and artwork approval, and shipping time is quoted separately. Mailers ship flat, which keeps freight volume down. To quote, send us:
- Product dimensions and weight, or the box size if you already know it
- Quantity per design
- Outside and inside artwork, or a design reference
- White or kraft board, if you have a preference
- Any insert and finishes
- Delivery destination
Use the mailer box quote form, or read the artwork and dieline checklist before you send files.