Postal Requirements
The United States Postal Service (USPS) establishes regulations for the mailing of business and personal correspondence.

Here are some basic guidelines to assist in the design of your mail piece. Visit the USPS web site for more information on envelopes, size requirements, tips, mailing costs and other topics.

Start by downloading and printing out a Size Template to test your mailpiece.

Postal Cards
Cards (or postcards) are an inexpensive way to get an immediate message to customers. When cards arrive in the mail, there's the message — no envelope to open! With First-Class cards, you pay a low rate and get all of the benefits, like forwarding and return, that come with First-Class Mail. And, if you mail at the single-piece First-Class Mail rate, there is no extra work involved — simply drop the cards in a collection box.

You may think that your mail piece is a "card," because it is a single sheet of paper. But to qualify for mailing at First-Class Mail card rates, a card must be:

• Rectangular
• At least 3-1/2 inches high x 5 inches long x .007 inch thick.
• No more than 4-1/4 inches high x 6 inches long x .016 inches thick.

If your mailpiece does not meet the dimensions above, then the Postal Service considers it a letter (and charges letter rate postage). With Standard Mail, there is a little more flexibility — there is no separate (lower) postage rate for cards, so you don't have to worry about your postcard being too big — because you're paying letter rates anyway. But make sure that your card is no larger than 6-1/8" x 11-1/2" x 1/4" thick. Larger than that and you'll have to pay flat (non-letter) postage rates.

Some mailers want to attach stickers, magnets, or other items to their cards. However, an attachment may disqualify a card for mailing at the First-Class card rate — or even make it non-mailable. The rules about attachments to cards are restrictive, so check with your local mailpiece design analyst (MDA) or business mail entry staff, who can tell you if your mail piece design will be mailable.

For more information about mailing postal cards go to www.usps.com/businessmail101/mailcharacteristics/cards.htm

Letters
You probably have a picture in your mind of what a "letter" is. Possibly you're using a standard No. 10 envelope for your letter, so that's easy to picture. However, if you decide to create a mail piece with its own special envelope or if you are designing a piece that will be folded to letter size, be sure to keep in mind the following size requirements for letters:

To be eligible for mailing at the postage rates for letters, a piece must be:

• Rectangular
• At least 3-1/2 inches high x 5 inches long x .007 inch thick.
• No more than 6-1/8 inches high x 11-1/2 inches long x 1/4 inch thick.

First-Class Mail that weighs 1 ounce or less, depending on the shape, may be subject to the nonmachinable surcharge. Customers can be unpleasantly surprised that they must pay extra postage when, for example, they mail a square greeting card. The Postal Service charges extra postage because mail pieces that are too stiff, too square, or unusually shaped often jam postal equipment and are difficult to process. This costs the Postal Service time and money — and may ruin your mail piece.

Many mailers fold sheets of paper to form letter-size pieces or newsletters. Folded pieces can save time and money because you're not paying for or stuffing envelopes. Using wafer seals or tabs to close the open sides of folded mail pieces is recommended.

For more information about mailing letters go to www.usps.com/businessmail101/mailcharacteristics/letters.htm

Large Envelopes and Flats (Nonletters)
The Postal Service uses the words "flats" and "nonletters" to refer to large envelopes, newsletters, and magazines. The words are interchangeable. Whatever you call them, flats must:

• Have one dimension that is greater than 6-1/8 inches high OR 11-1/2 inches long OR 1/4 inch thick.
• Be no more than 12 inches high x 15 inches long x 3/4 inch thick.

The maximum size for a flat gives you plenty of room to put lots of material in the envelope. But keep in mind that weight (usually) affects rate. The more you put in an envelope, the more it weighs, and the more it weighs, the more postage you pay, especially for First-Class Mail.

For more information about mailing flats go to
www.usps.com/businessmail101/mailcharacteristics/flats.htm

NOTE: We suggest taking a sample of your design to your local Postal Business Center or post office for advice and approval. It may save you valuable time and expense.