Guidelines for Mail Piece Design

In order to qualify for the lowest postal rates, your mailing must be automation compatible. There are two components to this requirement, the physical requirements of the mail piece you are sending, and the address quality requirements.

For the sake of brevity, we present only the requirements that apply to letter mail. For the same reason, we don't present minutia such as envelop address windows dimensions and suggested card stock grain. For the full set of requirements please see the Mailpiece Dimensions chapter of the USPS Publication 25.

Physical Requirements

To be automation compatible, your mail piece must

meet size and weight requirements,
be readable by automation equipment,
be sealed securely,
be made of good quality white or light-colored paper, and
contain no sharp or bulky items.

Size and Weight Requirements

The mail piece can weight up to 3.3 ounces and can be up to a quarter-inch thick. It's length and width must fall within the dimensions shows below.
Height between 3.5 and 6.125 inches, length 5 to 11.5

In addition, the length of the piece (the edge parallel to the address lines) divided by the height of the piece must be between 1.3 and 2.5. The example below shows a letter with an aspect ratio of 1.5, which qualifies.

Aspect ratio must be between 1.3 and 2.5

Readable by Automation Equipment

Machine Readable Layout

A Secure Seal

If you are mailing an envelope that is sealed, then you're all set. If your piece is a self-mailer then you must seal each piece with tape or have the printer put on a wafer seal.

Here are some ways to seal your booklet or self-mailer. You must use stickers, as staples are not allowed. One trick is to design your piece so that when you hold it so you can read the address label, the bottom edge is a folded edge. If the bottom is open, you need to use two wafers to seal it. If the top is open, you only need one seal.

First wafer seal example
Second wafer seal example
Third wafer seal example
Fourth wafer seal example

Address Quality

Address quality is a separate issue from making your mail piece automation compatible. To get the lowest possible rates, your address list must be processed by a software program that is certified by the US Postal Service as meeting the Coding Accuracy and Support System (CASS) requirements. These programs check each address in your list, standardize the address format, and add the last four digits to the zip code.

We have used online service List Cleanup a number of times. They charge $10 to CASS-certify your list (for up to 10,000 names). If you pay $25, you can have your list corrected against the last three years of move update cards, in addition to being CASS certified.