How to Mail Envelopes: The Big, the Bold, and the Bulky

It’s time to learn how to mail envelopes of all sizes. The steps involved in mailing a regular envelope may be simple, but not all envelopes meet the requirements of a standard piece of mail.

Below we’ll cover how to mail large envelopes, clasp envelopes, conformer envelopes, and remittance envelopes. We’ll also answer some of the most common questions about mailing envelopes.


How to Address an Envelope

An address needs a:

  • Person or Business name
  • Street address and unit number
  • City
  • State
  • ZIP code
  • Country (if sending internationally)


How to address an envelope: Do's and Don'ts


 The following mistakes are often made when addressing an envelope:

  • Addresses cannot be written in pencil.
  • Everything should be in capital letters.
  • There should be no punctuation.
  • Only list the recipient’s full legal name.
  • Abbreviations should be used for streets, apartments, states, etc.


Your envelope will likely reach its destination even if you don’t follow these rules, but this is what is preferred by the United States Postal Service. It’s best to follow all guidelines from the USPS to ensure your mail doesn’t get lost, returned, or sent to the wrong address.


✉️ Learn more in our article: How To Address An Envelope: What To Write On An Envelope.


How to mail an envelope

How to Mail Envelopes of All Sizes

Follow these five simple steps to mail an envelope:

  1. Seal the envelope.
  2. Clearly write the recipient's address in the middle of the envelope.
  3. Clearly write your own return address in the top left corner.
  4. Attach appropriate postage in the top right corner.
  5. Put the envelope in a USPS mailbox, give it to a mail carrier, or bring it to the post office.

It sounds simple enough, but it all gets a little trickier when you have large, small, or strange envelopes to mail.


How To Mail Large Envelopes

How To Mail Large Envelopes

Large envelopes, also known as ‘flats,’ are used to transport magazines, CDs, marketing materials, legal documents, and so on. They often safely fit standard size papers (8½ x 11) without folding the documents.

An envelope is considered large if it exceeds any of the following:

  • 6⅛″ in height
  • 11½″ in length
  • ¼″ in thickness 

Large envelopes are mailed much like other envelopes. As long as you have the appropriate postage, you do not need to go to the post office to mail them. Write the intended address on the envelope, write your own return address in the top left corner, place the correct postage in the upper right corner, and either drop it in your mailbox or hand it to your mail carrier.

The USPS considers any envelope larger than 12” in height, 15” in length, ¾” in thickness, or 13 oz in weight a package, which is subject to parcel prices dependent on the weight of the mail.


How To Mail Large Envelopes

How To Mail Clasp Envelopes

Envelopes with clasps are considered non-machinable envelopes and must be hand-canceled. Even if your clasp envelope weighs less than 1 oz, you will be charged a non-machinable surcharge.

If you have documents you need to mail that are in a clasp envelope, you can either put that envelope inside another non-clasp envelope or pay the non-machinable surcharge. In either case, put the return address in the top left corner, the sending address in the middle, and the appropriate postage in the top right corner.


How To Mail Large Envelopes

How To Mail Conformer Envelopes

Conformer envelopes are sturdy envelopes built to transport heavy, large, or important items through the mail. Lesser known than other envelopes, conformer envelopes are often used for items with firm corners that might tear through a regular envelope, or to transport fragile items, or items that cannot bend. If you are trying to ship a large item but don’t want to pay the added shipping costs associated with mailing a box, a conformer envelope is your ideal choice.

Conformer envelopes are usually made with stiff paperboard and can expand to hold several items or documents at once. The stiffness and durability of the material mean the sharp corners of books won’t pierce the paper, and their secure seal (usually a Tyvek® binding) means heavy items are kept securely within the package.

To mail a conformer envelope, ensure that the seal is tightly secured. Add your return address in the top left corner, and the recipient's address in the center. If the conformer envelope has a glossy texture, ensure you write the address with ink that’s clear and permanent, such as a fine tip Sharpie. Place the appropriate postage in the top right corner.  

It’s best to find out from the post office or a delivery service how much postage you will need to mail your conformer envelope, as this might change depending on the thickness and weight of the mail. Thick conformer envelopes won’t fit inside a mailbox, so it’s best to take these packages directly to the post office.


How To Mail Remittance Envelopes

Remittance envelopes are most commonly used to collect or transport money, usually in the form of charitable donations. They come with an attached extra flap the sender can use to write down their pertinent information, which is folded up and secured when the envelope is sealed.

Once you’ve filled out the fields on the remittance envelope, you can use the flap to seal in your personal information. If your remittance envelope does not have pre-paid postage, add one standard letter stamp in the top corner. Many remittance envelopes will have the address of its destination already on the envelope. If the address isn’t printed on the envelope, fill it out. Complete the return address section as well with your home or business address.


Common Mail Questions Answered

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Can You Mail Small Envelopes?

According to USPS, the smallest letter envelope mailing size is 3½” x 5”. A coin envelope, for example, is too small to be mailed on its own.  

To mail a small envelope, you would need to put the small envelope inside a larger one that meets the minimum dimensions to mail.


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Can You Send Black Envelopes In The Mail?

Yes, you can send black or colored envelopes in the mail, provided that the color is well contrasted between the information written on the envelope and the color of the envelope itself.

If you are mailing black envelopes, you need to write addresses in ink that’s clearly visible. Often pens or markers capable of writing on black paper are white or metallic. You can also use a printer to print addresses on stickers that you place in both address portions of the envelope.


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How Much Does It Cost To Mail A Large Envelope?

The stamp for a large envelope costs $0.70. If your mail meets the requirements of a large envelope, that’s the only cost to mail. 

Large envelopes are envelopes with a minimum - maximum length of 11½” - 15”, a height of 6⅛” - 12”, and thickness of ¼” - ¾”. A large envelope cannot exceed 13 oz; otherwise, it will be considered a package and be subjected to parcel pricing.


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Where Can I Buy Postage Stamps?

There are a few different places you can buy postage stamps, and we’ll start with the most obvious: the post office! You can purchase stamps at the counter during regular business hours, or from the USPS self-service kiosk available 24/7. A post office is, generally, the only place where you can buy a single stamp.

Other than the post office, you can buy postage stamps from Walmart, Kroger, Walgreens, as well as other pharmacies and grocery stores. You can also purchase stamps online from the USPS online store or from Amazon.


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Where Can I Buy Postage Stamps On Sunday?

Although the post office is closed on Sundays, many have a USPS self-service kiosk in the lobby that remains operational 24 hours a day, 7 days a week.

If your post office doesn’t have a self-service kiosk, you may also buy postage stamps on Sunday from Walmart, Kroger, and Walgreens, as well as online from USPS or Amazon.


Larry Says

Do you have more burning questions about postage stamps and the history of the United States Postal Service? Read Where to Buy Stamps: A Complete Guide to USPS Stamps to find the answers.


Next Up From Blue Summit Supplies

✉️  An Ultimate Guide to Poly Envelopes

✉️  All About Tax Form Mailing: 1099 and W2 Envelopes


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Jordan's passion for travel led her to design a career as a remote content marketer. Nearing 1000 published articles, she's spent the past decade using her interdisciplinary education to research and write content for a wide variety of industries. Working remotely, Jordan spends half of the year exploring different corners of the world. At home, she's content exploring fictional lands—Spark an immediate and detailed conversation by mentioning Game of Thrones, Red Rising, Star Wars, or Lord of the Rings.

1 comment

Shane Pelkey

Hi my name is Shane Pelkey first time here on your site. I was researching for an answer to a question I originally had for myself. Reading through your website it seems you would know this answer that many others have answered differently. Anyways can I get a shipping label/how for a basic white 10×6 envelope (ROUNDING HERE)? I am also meeting the requirements for a year round stamp, and that cant exceed 1oz. Furthermore staying under the 1/4 in girth measurement following by the 61/8H × 111/2L requirements. If there’s anyway possible for me to do this withought having to buy the shipping label I would really appreciate it.

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