- What a supplier actually needs to quote and sample your mailer box
- Artwork file requirements — and what happens when files arrive wrong
- Three sample types — and which one you actually need
- The overlooked variable: inner vs. outer dimension confusion
- Evaluating received samples before approving production
- Comparing quotes from different suppliers fairly
- Specification Notes for Brand Partners
TL;DR: A poorly briefed sample request adds 2–3 weeks to your timeline before a single box is made — the spec sheet you submit on day one determines everything downstream.
TL;DR: Suppliers need at least 6 data points to quote accurately; missing even one (typically inner dimensions vs. outer) triggers a requote cycle that delays production samples by 10–15 working days.
What a supplier actually needs to quote and sample your mailer box #
Most quotation delays trace back to the brief, not the supplier. When a request comes in without clear dimensional intent, material call-out, or print file guidance, we have two options: guess and requote later, or ask and wait for answers. Either way, the project stalls.
The six data points we need before we can open a job file are: inner dimensions (L × W × D in mm), board grade and flute type, print specification (outside only, or inside + outside), surface finish, quantity tiers, and shipping destination. That last one affects carton configuration and pallet count, which feeds back into unit pricing. Leave any of these blank and the quote you receive will carry assumptions — which rarely match what you had in mind.
On board grade: for a standard direct-to-consumer mailer, we typically quote 3-ply E-flute corrugated at 140gsm kraft liner / 100gsm fluting / 140gsm liner. If you’re shipping heavier products (above 2 kg), call out 5-ply B-flute or EB double-wall and confirm your maximum box weight. Without that, we default to the lighter construction and the compression strength may not meet your ISTA 3A transit requirement.
Artwork file requirements — and what happens when files arrive wrong #
Print-ready files for mailer boxes must be supplied as vector PDF (PDF/X-4 preferred) with a minimum of 3mm bleed on all sides and all fonts embedded or converted to outlines. Image resolution for any embedded raster elements should be 300 dpi at final output size. Files submitted as low-resolution JPEGs or with live text cause a pre-press hold that typically adds 3–5 working days before plates are made.
Colour: we work to G7 Master calibration on our offset lines, which means your Pantone references need to be specified as solid coated (C) values, not uncoated (U). A Pantone 286 C and Pantone 286 U will print differently on kraft board — that distinction matters if your brand has tight colour standards. For digital print short runs (under 500 units), we match to your supplied CMYK profile; expect a Delta-E tolerance of ≤3.0 under D50 illumination, which aligns with ISO 12647-2 print quality standards.
One common file issue we flag at intake: dieline and artwork supplied as separate files on different scales. Our pre-press team catches this during our PR-01 file intake check, but when files arrive misaligned, it adds a full pre-press correction cycle. Supply both layers at 1:1 scale in the same document to avoid it.
Three sample types — and which one you actually need #
Suppliers offer different sample types for good reason. Choosing the wrong one for your stage wastes time.
| Sample Type | What It Tests | Typical Turnaround | Cost |
|---|---|---|---|
| White (unprinted) structural sample | Box dimensions, flute, assembly, fit | 5–7 working days | Usually free or low nominal fee |
| Colour printed proof (pre-production) | Print accuracy, colour match, finish | 10–14 working days | Charged; credited on order |
| Production sample (from live run) | Full spec including print, finish, inline QC | 20–25 working days | Included in production batch |
For first-time briefs, request a white sample first. It costs little and tells you immediately whether your inner dimension spec works for your product. Running a full printed proof against dimensions that turn out to be wrong means re-plating and re-sampling — a cost and timeline hit that a white sample would have prevented.
If your product is already dimensionally confirmed and you’re evaluating print quality for a premium mailer, go straight to a printed proof and hold evaluation against your brand colour guide. Do not accept colour approval via phone screen photography — request a physical sample and evaluate under D50 standard illuminant, per ISO 3664 viewing conditions.
The overlooked variable: inner vs. outer dimension confusion #
This is the source of more requote cycles than any other single issue. When you specify a mailer box as 300 × 200 × 100mm, do you mean the inner cavity or the outer footprint? For E-flute corrugated, the board calliper is approximately 1.5–1.6mm per wall, so a box with 300mm inner length will have a 303–304mm outer length. For EB double-wall, each wall adds roughly 4.5mm, bringing the outer to 309mm.
That 9mm difference matters when your product sits in a shipping carton sized for a specific pallet configuration, or when your product sleeve needs to fit cleanly over the outer box. We default to quoting against inner dimensions unless you specify otherwise — and we note this assumption explicitly on every quotation so it can be corrected before sampling begins.
Evaluating received samples before approving production #
When your white sample or printed proof arrives, work through this sequence before signing off:
- Measure all three inner dimensions with a steel rule, not a tape measure. Tolerance expectation on our structural samples is ±1.5mm per dimension under GB/T 6543 corrugated box standard.
- Check the assembly: does the lid close flush without bowing? On auto-bottom constructions, does the base lock without manual pressure on all four corners?
- For printed proofs: check colour under consistent lighting (not window light). Check register on any fine text or logo elements — our offset register tolerance is ±0.25mm; anything outside that on a proof should be flagged before approval.
- Check coating adhesion. Run your thumbnail across any spot UV or soft-touch laminate panels. Delamination on a sample is a red flag for substrate prep issues.
- If inside printing was specified, check for ink offset or blocking — fold the box closed and reopen it; ink should not transfer to the opposing face.
Allow 3 working days for your evaluation. Rushing approval on a sample you haven’t fully reviewed is how production print errors get locked in.
Comparing quotes from different suppliers fairly #
A quote comparison only works if all suppliers quoted the same specification. The most common mismatch we see: one supplier quotes 130gsm liner and another quotes 150gsm liner — both called “E-flute kraft,” both look like competitive pricing until you read the spec sheet.
Request an itemised quote that breaks out: board specification (liner / fluting / liner GSM), flute type, print colours and process, surface finish callout, and minimum order quantity (MOQ). Our standard MOQ for custom printed mailers is 500 units for digital print and 1,000 units for offset, so if another supplier quotes 200 units at a lower unit price, confirm whether that’s screen-printed or digitally printed and check the colour fidelity against your brand standards.
Lead time should also appear on every quote. Our production lead time for a standard single-wall mailer with offset print is 18–22 working days after artwork approval and deposit receipt. If a supplier quotes 10 days for the same spec, ask what’s being compressed — pre-press, curing time, or transit.
Specification Notes for Brand Partners #
When you brief us on an e-commerce mailer box, the most useful starting point is a completed dimension sheet with inner L × W × D, your product weight, and a reference image of the product going in. That combination lets our structural team check compression strength adequacy against your shipping method without coming back with clarifying questions.
The spec gap that causes the most first-round sample iterations is missing finish callout. “Gloss” and “matte” are not complete finish specifications — we need to know whether you mean a gloss or matte laminate, a water-based coating, or a UV coating, because each has a different feel, cost, and lead time implication. A quick call or sample swatch exchange before briefing saves a full iteration.
Our standard sampling timeline is 5–7 working days for white samples and 10–14 working days for printed proofs, measured from confirmed artwork and approved dimensions. Factory holidays (particularly Chinese New Year, Golden Week) can extend this by 5–10 working days — flag your launch date early and we’ll work back from it together.
What dimensions should I give the supplier — inner or outer?
Always specify inner dimensions. This is what matters for your product fit, and it’s what we quote against by default. We note the assumption on every quote so you can confirm before anything is made.
How long does it take to get a printed proof sample?
For a standard offset-printed mailer with one surface finish, our printed proof turnaround is 10–14 working days from artwork approval and dimension sign-off. Complex jobs with inside print and multiple finishes run closer to 16–18 working days.
Can I order a sample before committing to a full production run?
Yes — and for first-time orders we recommend it. The cost of a printed proof is typically credited against your production order value. Whether the credit applies in full or partially depends on the sample complexity, which we confirm at the time of quoting.
Planning a packaging project? Contact our team to request a complimentary specification review and sample quote.
Always spec your inner dimensions against the actual filled product weight, not the product alone — we’ve had 3-ply E-flute quoted and sampled correctly, then failed ISTA 3A on transit because nobody accounted for the 340g candle vessel plus packing fill pushing the loaded box past 2 kg.
Spent three rounds of white samples with a Shenzhen supplier last year because we’d given outer dims instead of inner — their default assumption was a 6mm wall offset, ours was 4mm, and the tray fit was off every time. Nobody flagged the ambiguity until sample two. Now our brief template has a mandatory “inner or outer?” checkbox before anything gets sent.
The 140/100/140 kraft spec is a reasonable default, but we’ve found it starts showing crush failures on the scorer lines well below 2 kg when the product is a glass bottle — the weight distribution and rigidity of the contents matters as much as the total gram count. We moved to 160gsm liner on a 900g candle SKU after two damage claims in the same postcode zone.
Switching to FSC-certified E-flute last year meant requalifying our entire board spec with the supplier, and they couldn’t carry the 140/100/140 in certified stock — we ended up at 150/112/150 which changed our compression figures enough that we had to rerun ISTA 3A on three SKUs. Worth it for the retailer requirements, but that’s an easy 6 weeks nobody budgets for in the sampling timeline.
One thing that doesn’t come up enough in sample briefs: aqueous coating vs. soft-touch laminate on the outer liner. Aqueous adds maybe 3–5 working days to a pre-production proof cycle and is usually included in the base finish quote, whereas soft-touch laminate typically gets broken out as a separate line item and can push pre-production turnaround closer to 14 days because it’s a secondary process the supplier often outsources. If your sample request doesn’t specify which finish you’re testing, the supplier defaults to uncoated or aqueous and you won’t catch the laminate handling differences until production.
Worth flagging on the EB double-wall point: we ran BCT (box compression tests) on a 600 x 400 x 300mm EB flute mailer at 3 different humidity conditions for a skincare client shipping into Southeast Asia, and at 85% RH the compression strength dropped from 1,840N to under 900N even with a C1S liner. If your brief doesn’t call out destination climate, the supplier’s default BCT data is basically useless.
Die 3mm Bleed-Vorgabe klingt erstmal trivial, aber wir hatten einen Fall wo ein Folding-Carton-Lieferant in Guangdong die Bleed-Zone auf der Klebelasche miteingerechnet hat — Ergebnis war ein 4mm Weißrand an der Seitennaht nach dem Stanzen. Passiert genau einmal, danach steht bei uns im Template explizit “bleed excludes glue flap area” mit einem roten Hinweiskasten.
Die-cutting tooling on E-flute mailers gets quoted as a one-time cost but it’s not — we had a supplier in Dongguan charge a retooling fee of ¥1,800 when we adjusted inner dims by just 8mm on one axis six months after the original run, because the crease matrix had to be remade. If you’re still finalising your product packaging during the sample phase, it’s worth asking upfront whether dim changes within a certain tolerance window are covered under the original tooling cost or trigger a new charge.