Made with Pride in the USA
The Polybag versus the Constructed Poly Envelope

Why constructed poly envelopes are
better than polybags for direct mail

poly bag

Polybags, also known as polyethylene bags, provide an economical shipping choice that protects against dirt, moisture, and tampering.

They can be clear or opaque and printed with images and type. They’re available in several different thicknesses, referred to as mils, to protect and package as many different products as possible.  Lightweight polybags (1.6 mils) are cheap and used for temporary storage (think dry cleaning, newspaper, and grocery bags). 2 mil poly is typically used for light or medium weight. Heavyweight polybags (3 mils and higher) are used when strength and durability are essential.

poly bag envelope

Poly bags have grown in popularity thanks to eCommerce and are used to mail just about everything from food to clothing, books, nails, tools, and automotive parts. 

But should you use them when you want a recipient to take an action of some type – make a purchase, return a survey, contribute to charity?

Despite being referred to as “direct mail specialty envelopes” in online searches,
polybags aren’t designed for response-driven direct mail.

 The reasons why are detailed here.


Poly bags and the post office

No one likes surprises at the post office, and here’s your first one you may encounter with a polybag. The USPS will allow a poly bag to mail as an auto flat, but here’s the rub – this often doubles postage. That’s surprise number one.

 And if you try and mail poly bags that are too flimsy, you may be in for even more unwelcome surprises. Remember that cheap, thin 1.6 mil polyethylene most polybags are made from? It’s not automated for postage, which means problems at the post office.

Postal machines and scanners don’t like a thin, unevenly filled polybag. If the polybag has spaces where it’s completely flat and unfilled, the poly can fold, get caught in machinery and prevent the shipping labels from getting scanned properly.

A thin polybag that gets caught in machinery gets held up at the post office. And recipients are left wondering what happened and why it’s taking so long for their item to arrive.  You’re left holding “the poly bag,” so to speak.

Constructed poly envelopes made specifically for direct mail

Maybe you’re grappling with questions like these:

  • Will your mailing arrive quickly and to the right place?
  • Where should the label go?  How should it be printed?
  • How should the mailer be sealed?
  • Can you print the address directly on the envelope, or do you need an address label?
  • What are mailer size restrictions?
  • Are your allowances for insertion tolerance correct?
  • Do you need a paper label for a barcode?
  • Am I spending more than I should on postage?

Here’s what it boils down to.

If you could increase the odds that your direct mail piece would have an edge
over all the competing items in a mailbox to attract the recipient’s attention and
get opened – wouldn’t you do it?

The EnvyPak Automation Letter Rate (ALR) Envelope



The EnvyPak ALR envelope is a sturdily made, fully constructed four-sided clear poly envelope with welded sides and bottom and a sealable flap. It’s constructed with USPS approved crystal-clear 4.5 mil poly (not the flimsy 2 mil polyethylene used for polybags).

 EnvyPak ALR envelopes will work exceptionally well throughout the postal process because they’re made with rigid polypropylene. It won’t get caught in postage equipment.

And here’s another difference between the poly bag and a constructed poly
envelope:  EnvyPak is the only clear poly envelope that qualifies for
automation letter postage.

The EnvyPak ALR envelope still allows plenty of room for creative flexibility, meets postal guidelines and sails through inserting and processing equipment with flying colors.

USPS approval and poly envelope specifications

It took ten years of rigorous testing and engineering for this clear poly envelope to meet all USPS specifications for full automation rates.

Here are a few of the USPS specifications:

  • Height between 4” – 6”
  • Length between 8” – 10.5”
  • EnvyPak smooth anti-reflective polypropylene is required on address panel side
  • Address and IMB (International Mail Barcode) can be printed on insert to show through the anti-reflective polypropylene
  • Maximum clear gap of 0.2” (clear gap occurs when insert inside envelope shifts to the right inside of an envelope and it is possible to “see straight through” both sides of the envelope)

Click here For the complete list of EnvyPak ALR envelope specifications.

Creativity and the constructed poly envelope

Unlike polybags, EnvyPak ALR (Automation Letter Rate) poly envelopes are designed specifically for direct-response mailing campaigns. Direct mail sent in an EnvyPak envelope creates a positive, emotional impact because you can see what’s inside. And you can also print directly onto the envelope.

And you can be creative with how you use it.

  • You can print the address and barcode directly on the insert to show through the clear envelope, which allows for creative approaches between the insert and envelope design.
  • A paper address label can finally be eliminated with an EnvyPak envelope because the address can be printed on the inside content to show through.
And what about those white bands?There are unique ways to create a design that “blends” the white bands required by the USPS. Here are two examples that do that in artistic fashion

“Futuristic” ALR poly envelope

poly bag

EnvyPak envelopes with custom metallic print create a striking mail piece. Metallic PMS colors are available or we can print any PMS color on top of 877 silver. The silver shows through to create sheen.

This envelope uses white, 877 silver, blue/green gradient plus a white overprint for the copy and address block. The address block can be ink-jetted with solvent or UV ink.  It was machine inserted and sealed with glue. 

Translucent Registration


Think of an EnvyPak clear poly envelope as a blank canvas. Print used on the envelope can mask, compliment, highlight, or in the case of our sports car mailer, register with print on the insert.

  • This envelope was printed and converted inline on a Flexo press before the insert was printed.
  • The insert’s graphics were then adjusted to properly register with print on the envelope.
  • Low percentages of silver and white were also used to give the design a bright effect that seemed to pop off the envelope.

Save on postage with full automation

And here’s the best reason to try an EnvyPak ALR clear poly direct mail envelope.

 EnvyPak’s Automation Letter Rate (ALR) poly envelope can yield up to 54.6% savings in postage, savings traditionally only attainable with paper envelopes.

In  fact, EnvyPak’s ALR envelope mails for the exact same postage as a paper envelope. Depending on the quantity you need, it can be manufactured for either hand or machine inserting the contents.

This opens the door for both large and small marketers to have access to a unique, high-impact clear envelope that drives response.

Frequently asked questions about EnvyPak clear poly envelopes

Ready to learn more?

When you’re ready to start your next direct mail project, give us a shout.  We’re happy to help answer your questions.

Email:; or phone 877-835-3052.
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