Postal Basics

To execute a successful mail campaign it is critical that your design and address-set up meet the requirements of the U.S. Postal Service. Rules include but are not limited to envelope sizes, position and sequence of address lines, graphic restrictions, and mandatory clear zones. To support your efforts, we have included several of the most important guidelines which should prove helpful.

To review the complete list of regulations, please reference the Domestic Mail Manual (DMM), published by the U.S. Postal Service which is available on the Internet at You can also check with your local Postmaster about additional requirements in the area from which the envelopes will be mailed.

Clear Zones

When the envelope is addressed with a name, address and ZIP code, the Postal Service will read the ZIP code with an OCR (Optical Character Reader) and print a barcode on the envelope in the lower right-hand corner. This is why you must keep a “clear zone” on the lower right-hand corner of the envelope (now 5/8” up from the bottom and 4 3/4” out from right edge).

Intelligent Mail® Barcode

The Intelligent Mail barcode (formerly known as the 4-State Customer Barcode) is the next generation of USPS® barcode technology used to sort and track letters and flats. Intelligent Mail barcode technology, among other things, combines the capabilities of the POSTNET™ barcode and the PLANET Code® barcode into one unique barcode.

The Intelligent Mail barcode combines the data of the existing POSTNET™ and the PLANET Code® barcodes, as well as other data, into a single barcode. The Intelligent Mail barcode is a type of height-modulated barcode, that uses four distinct vertical bar types (full, tracker, ascender and descender) as shown below.


Postcard Layout Guide

This template should be used when laying out the mailing side of your postcard to ensure that your layout conforms to postal regulations for automated mailings.


Design Elements & Backgrounds

You should avoid the use of background colors or photographic images with greater than 7% ink density and vertical lines in or around the blue shaded areas. Those elements might interfere with the scanner’s ability to read the postal barcode, causing a white label to be slapped onto your design to serve as a clean base for an inkjetted barcode. The result will not be pretty.

Sizes & Postage

  • The minimum size for a postcard is 3 1/2” x 5”
  • The maximum size for a postcard that mails at postcard rate is 4 1/4” x 6”
  • The maximum size for a postcard that mails at letter rate is 6 1/8” x 11”


  • The minimum thickness for a postcard that measures 4 1/2” x 6” or smaller is .007 in
  • The maximum size for a postcard that mails at postcard rate is 4 1/4” x 6”
  • The maximum size for a postcard that mails at letter rate is 6 1/8” x 11”

The Resource Download Site

The USPS website has a list of resources for the Intelligent Mail® Barcode.

For the Resource Download Site, visit:

To check the Intelligent Mail® Barcode Question and Answer PDF, visit:

To understand the steps in creating your Intelligent Mail® Barcode, visit: