Custom mailer boxes that ship without an outer carton.
Self-locking corrugated mailers printed inside and out — strong enough for the parcel network, quick to pack, and sized to your product so you don’t pay to ship air.
- No tape needed to close
- Print outside, inside or both
- E-flute for most products, B-flute for heavier ones
- Minimum
- 50 units
- Flute options
- E / B
- Production
- 8–10 days
- Style
- Roll-end tuck front
- Board
- E-flute, white
- 4/1 (outside + inside)
- Size
- 9 × 6 × 3 in
Mailer box structures compared.
“Mailer box” usually means a roll-end tuck front (RETF) box: a one-piece corrugated blank whose side walls fold over (“roll”) to make double-thick ends, with a lid that tucks into the front. It locks without tape, stacks well and looks finished on the doorstep. Variations suit different products:
| Structure | How it closes | Best for |
|---|---|---|
| Roll-end tuck front | Lid tucks into the front wall; double-thick side walls | Most e-commerce and subscription boxes |
| Roll-end tuck top with dust flaps | Lid tucks in with inner flaps closing the gaps | Products that shed dust, powders, apparel |
| Ear-lock (cherry-lock) mailer | Small tabs lock the lid shut | Heavier contents, tamper resistance |
| Double-wall front mailer | Extra-thick front panel | Premium feel, heavier items |
| Mailer with tear strip | Perforated strip opens the lid; second adhesive strip reseals | Fashion and anything with returns |
All of them ship flat and fold up in seconds — ask for an assembly video for your packing team.
E-flute or B-flute?
Corrugated board is made of a wavy middle layer (the flute) glued between two flat liners. The flute size changes the thickness, strength and print quality.
| Flute | Approx. thickness | Strengths | Use it for |
|---|---|---|---|
| F-flute | ~1/32 in (0.8 mm) | Very thin, fine print | Small premium mailers, cosmetic outers |
| E-flute | ~1/16 in (1.6 mm) | Crisp folds, sharp printing, good crush resistance | Most mailers up to ~5 lb |
| B-flute | ~1/8 in (3.2 mm) | More cushioning and stacking strength | Heavier, fragile or glass products |
If your product is under about 5 lb and not fragile, E-flute is almost always the right call: it prints beautifully and keeps the box slim. Heavier or breakable products move to B-flute or add an insert. See corrugated boxes for the full guide.
Mailer box specifications.
| Styles | Roll-end tuck front, tuck top with dust flaps, ear-lock, double-wall front, tear-strip |
|---|---|
| Board | F-, E- or B-flute corrugated; white or kraft outer liner |
| CMYK + Pantone outside; 1-color or full color inside; white ink on kraft | |
| Coatings | Matte or gloss aqueous; lamination on premium mailers |
| Add-ons | Inserts, dividers, tear strips, peel-and-seal strips, foil logos |
| Size range | From about 4 × 4 × 2 in up to 24 × 18 × 8 in |
Sizing mailers for parcel pricing.
Carriers bill the higher of actual weight and dimensional weight (length × width × height in inches ÷ 139 for UPS and FedEx). Since July 12, 2026, USPS uses the same divisor for parcels over one cubic foot and rounds each dimension up to the next whole inch. A mailer just a fraction of an inch over a round number can push you into a heavier price bracket.
Practical steps:
- Measure the product as packed (with any tissue or insert) and add 1/8–1/4 in clearance per side.
- Round the inside size so the outside size lands just under a whole inch.
- Use an insert instead of a bigger box to stop small items moving.
We do this check on every mailer quote — tell us your carrier and we’ll flag sizes that cost you money.
Frequently asked questions
Do mailer boxes need an outer shipping box?
Usually not. Corrugated mailers are built to ship on their own via UPS, FedEx and USPS. For very heavy or fragile items, or for retailers with specific requirements, an outer carton may still be needed.
What is the most popular mailer box size?
Common sizes include 6 × 4 × 2, 9 × 6 × 3 and 12 × 9 × 4 inches, but the right size is the one that fits your product snugly. All our mailers are made to custom dimensions.
Can mailer boxes be printed inside?
Yes. Inside print — anything from a one-color message to full-color patterns — is the most popular mailer upgrade.
How much weight can a mailer box hold?
E-flute mailers comfortably carry most products up to around 5 lb; B-flute handles heavier loads. Tell us the product weight and we will recommend the board.
Are mailer boxes recyclable?
Corrugated mailers are widely recyclable in curbside programs. Avoid plastic lamination if recyclability is a priority.
Get a mailer that fits — and ships cheaper.
Send your product size and carrier. We’ll recommend a mailer size and board and send a 3D proof.