Postal / Bubble Lined Mailers / Envosafe Secure

See also: Envosafe Protect

Order Code	Description	Internal Dimensions (mm)	Royal Mail	PackQuantity
15PA000	Secure - white A/000	110 x 165	letter	200
15PB00	Secure - white B/00	120 x 215	letter	200
15PC0	Secure - white C/0	150 x 215	letter	100
15PD1	Secure - white D/1	180 x 265	large letter	100
15PE2	Secure - white E/2	220 x 265	large letter	100
15PF3	Secure - white F/3	230 x 335	large letter	100
15PG4	Secure - white G/4	240 x 335	large letter	100
15PH5	Secure - white H/5	270 x 360	packet	100
15PJ6	Secure - white J/6	300 x 445	packet	50
15PK7	Secure - white K/7	350 x 470	packet	50

 

Envosafe Secure Bubble Lined Mailers (White) — Overview

Bubble lined mailers are designed to protect small, fragile, or easily scuffed items during postal transit while keeping the outer pack lightweight and easy to handle. This collection lists Envosafe Secure white bubble lined mailers in a range of internal sizes (shown in millimetres on this page) and includes a postal format indicator (for example, “letter”). The combination of a paper outer and a cushioned bubble lining helps reduce surface abrasion and impact damage compared with unpadded envelopes, while still presenting as a neat, professional mailer.

Because the dimensions shown are internal, they are the most useful reference for fit: they indicate the usable space for your product once inserted. When choosing a size, allow extra room for the thickness of the item and any additional protective wrap you may add (such as tissue, foam, or a small inner bag). Overfilling can stress seams and closures and may also affect postal thickness limits.

Envosafe Secure Bubble Lined Mailers — Helpful Guide

What “Secure” bubble mailers are used for

Secure bubble mailers are commonly used for shipping items that benefit from both privacy and protection. Typical examples include cosmetics, small electronics accessories, jewellery boxes, stationery, spare parts, samples, and printed materials that must arrive clean and crease-free. The bubble lining cushions against knocks, while the paper outer helps resist tearing and punctures in normal handling.

Understanding the size codes (A/000 to K/8)

Many bubble mailer ranges use a standard size-code system (A/000, B/00, C/0, D/1, E/2, F/3, G/4, H/5, J/7, K/8). These codes correspond to commonly used internal dimensions. A widely used reference set lists the following internal sizes in inches: A/000 (3 7/8" x 6 3/4"), B/00 (4 7/8" x 8 3/4"), C/0 (5 7/8" x 8 3/4"), D/1 (7 1/8" x 10 3/4"), E/2 (8 1/2" x 11"), F/3 (8 1/2" x 13 3/4"), G/4 (9 1/2" x 13 3/4"), H/5 (10 1/2" x 14 3/4"), J/7 (14 1/8" x 18 3/4"), and K/8 (19" x 18 3/4").

On this collection page, the internal dimensions are shown in millimetres for each order code (for example, A/000 is listed as 110 x 165 mm). Use the internal dimensions on this page as your primary reference, and treat the size code as a quick shorthand when comparing mailers across ranges.

Types of bubble lined mailers in this category

• White paper bubble lined mailers (Secure range)
  

  This collection focuses on white bubble lined mailers in the Secure range. They are intended for postal despatch where you want a clean outer appearance and built-in cushioning. The table on this page lists each mailer by order code, size code, internal dimensions (mm), and pack quantity.

Products and sizes available on this page (by size code)

The following size codes are shown in the collection table. Choose based on the internal dimensions and the thickness of your contents:

• A/000 — compact internal size for small, flat items (example shown: 110 x 165 mm).
• B/00 — slightly longer format for small accessories and documents (example shown: 120 x 215 mm).
• C/0 — wider option for thicker stationery packs or small boxed items (example shown: 150 x 215 mm).
• Additional sizes — the Secure range typically continues through larger formats (D/1, E/2, F/3, G/4, H/5, J/7, K/8). Refer to the table on this page for the exact internal dimensions and pack quantities offered in this collection.

Case Study: Reducing damage and returns for small, fragile items

A small fulfilment operation shipping mixed “small parcel” items (such as cosmetics, accessories, and small components) often faces two recurring issues: surface scuffs from movement inside the pack and corner damage from impacts during sorting. Switching from unpadded envelopes to bubble lined mailers can reduce both problems because the bubble lining acts as a built-in buffer and helps keep the item from rubbing directly against the outer paper. In practice, the biggest improvement usually comes from matching the mailer size to the product: a snug fit reduces movement, while leaving enough clearance prevents seam stress and closure failure.

In this scenario, the team standardised a small set of sizes (for example, A/000 for compact items and B/00 or C/0 for slightly larger packs) and introduced a simple packing rule: add a thin inner wrap for items with sharp edges, and avoid overfilling beyond the internal dimensions. The result is a more consistent packing process and fewer “arrived damaged” reports, especially for items with delicate finishes.

How to choose the correct bubble lined mailer

1) Start with internal dimensions (fit), not external dimensions

The internal dimensions shown in the table are the usable space for your contents. Measure your product at its widest points (length and width) and add clearance for insertion. If your item is rigid or boxed, allow extra room so corners do not catch on the lining. If your item is flexible (for example, textiles), you can often choose a closer fit.

2) Consider thickness and postal format limits

Postal categories are often driven by thickness as much as length and width. For example, Royal Mail’s published maximum thickness for “Letter” is 5 mm, while “Large Letter” allows up to 25 mm (2.5 cm), with maximum face dimensions of 24 cm x 16.5 cm for Letter and 35.3 cm x 25 cm for Large Letter. Bubble lined mailers add thickness by design, so even if the face dimensions fit a “Letter” template, the packed thickness may push the item into “Large Letter.”

Use the “Royal Mail” column on this page as a starting point, then confirm your packed thickness (including the item and any inserts). If you are close to a threshold, test-pack one unit and measure the thickest point with a ruler or callipers.

3) Match the mailer to the item’s risk profile

• Fragile surfaces (polished, printed, coated): choose a snug size and consider an inner sleeve to prevent abrasion.
• Sharp edges or corners: add an inner wrap or small carton to prevent punctures and seam stress.
• Multiple items in one pack: separate items with a divider (paper, tissue, or a small bag) to reduce rubbing.

4) Plan for labels, barcodes, and handling

Ensure the chosen mailer provides enough flat area for your shipping label without covering seams or folds. If you use automated label application, keep the label placement consistent across sizes. For returns workflows, consider whether you need space for an internal returns note without overfilling.

Packing tips for better protection and smoother despatch

• Do a “shake test”: after sealing, gently shake the mailer. If the contents move significantly, consider a smaller size or add a light void-fill layer.
• Keep closures clean: dust, oils, or fibres can reduce adhesive performance. Seal on a clean, dry surface.
• Avoid overstuffing: forcing bulky items can stress seams and may increase the chance of tearing during sorting.
• Protect corners: for boxed items, add a thin corner protector or wrap to reduce corner crush.
• Use the right label stock: choose labels that adhere well to paper surfaces and remain readable if exposed to light moisture.

Common mistakes to avoid

• Choosing by size code alone: always confirm the internal dimensions in millimetres shown in the table.
• Ignoring thickness: bubble lining adds bulk; packed thickness can change the postal category even when length/width fit.
• Sending sharp items without an inner wrap: sharp corners can puncture the lining and outer paper under pressure.
• Overloading with inserts: leaflets, samples, or multiple items can push the pack beyond its intended capacity.

Frequently Asked Questions