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Direct Mail Design Basics

Are you looking to design your mailing campaign for maximum deliverability? It doesn’t have to be a daunting task if you adhere to these key USPS (United States Post Office) tips.


The USPS prefers a sans-serif font for addressing mail pieces. The font size should be eight-point or higher, and all capital letters. The difference between serif fonts and sans-serif fonts is that sans(without)-serif fonts are without little feet on the bottom of the letters. This means the USPS equipment can better read the address block of your mail piece.


When picking out an envelope size or designing a self-mailer, you will need to determine if you are mailing at letter rates or flat rates. For letter rates the max size of the envelope or oversized card is 6.125” x 11.5”. A folded self-mailer or booklet max size is 6” x 10.5”. If your mailpiece is larger, your piece will mail out with flat rate postage. Note the difference between postage for a Marketing Mail Letter vs. a Marketing Mail Flat can be as high as 30.1 cents per piece. The most common direct mail envelope sizes are a #10, a 6”x9”, and a 9”x12” envelope. The #10 and 6”x9” envelopes both mail with letter rates. The 9”x12” envelope mails out with flat rate postage.

Another element to think about is if you want to use a window envelope or a standard envelope. Window envelopes are typically used for bills, statements, or other transactional mailings. A standard closed face envelope may give a mail piece a more personal feel.


The background color of your envelope should be white, neutral, or a light pastel color. This allows USPS equipment to read the barcode and address block on your mail piece. Avoid dark, bright, black, and fluorescent colors as they prevent the USPS equipment to read barcodes, resulting in misreads, postage surcharges and returned mail. If you print an envelope or self-mailer in full color, knock out the address block. Use a standard window from a #10 envelope to determine the size of the knockout. The size of a standard #10 window is 1.125” x4.5”. If you knock out the area with a 1.5” in height you will have enough room for addressing while keeping a .125” clearance to the left and right and a .028” clearance from top and bottom.

By implementing these key design tips you can ensure that your next mailing campaign has maximum deliverability which will increase your response rates and save you from costs incurred from undeliverable mail.

For more information on designing for direct mail contact us at for your copy of the USPS Best Practices PDF.

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