Decoding the USPS Intelligent Mail Barcode

The Intelligent Mail Barcode (IMB) is a 65-bar barcode for use on mail in the United States. The term “Intelligent Mail” refers to services offered by the United States Postal Service for domestic mail delivery. It effectively incorporates the routing ZIP code and tracking information included in previously used postal barcode standards.Use of the barcode provides increased overall efficiency, including improved delivery, and new services.

The main component of the barcode is the Delivery Point Identifier (DPID), an eight-digit number that encodes the destination of the mail. This is the only part filled by a user, the other components are filled automatically.

Uses of IMB:

  • Better visibility into the mailstream.
  • Ability to track individual pieces, handling units and containers.
  • Receive information about mail preparation and address quality.
  • Determine when a mailing was inducted to the postal system.
  • Address correction services, if requested.
  • Mail induction (start-the-clock) information.
  • Optional Confirm Service.


1.Barcode identifier:

  • A Barcode Identifier is assigned by the United States Postal Service to encode the presort identification that is currently printed in human readable form on the optional endorsement line (OEL). It is also available for future United States Postal Service use. This is accomplished using two digits, with the second digit in the range of 0–4. The allowable encoding ranges are 00–04, 10–14, 20–24, 30–34, 40–44, 50–54, 60–64, 70–74, 80–84, and 90–94.
  • 2. Service type identifier (STID):

    A three-digit value represents both the class of the mail (such as first-class, standard mail, or periodical), and any services requested by the sender.

    3. Mailer ID:

    A six- or nine-digit number assigned by the United States Postal Service identifies the specific business sending the mailing. Higher volume mailers are eligible to receive six-digit Mailer IDs, which have a larger range of associated sequence numbers; lower volume mailers receive nine-digit Mailer IDs. To make it possible to distinguish six-digit IDs from nine-digit IDs, all six-digit IDs begin with a digit between 0 and 8, inclusive, while all nine-digit IDs begin with the digit 9.

    4. Sequence Number:

    A mailer-assigned six- or nine-digit ID specific to one piece of mail, to identify the specific recipient or household. The mailer must ensure that this number remains unique for a 45-day period after the mail is sent if a Full Service discount is claimed; otherwise, it does not have to be unique. The Sequence Number is either six or nine digits, based on the length of the Mailer ID. If the Mailer ID is six digits long, then the Sequence Number is nine digits long, and vice versa, so that there will always be fifteen digits in total when the Mailer ID and the Sequence Number are combined.

    5. Delivery point ZIP code:

    This section of the code may be omitted, but if it is present, the five-, nine-, or eleven-digit forms of the ZIP code are also encoded in the Intelligent Mail barcode. The full eleven-digit form includes the standard five-digit ZIP code, the ZIP + 4 code, and a two-digit code indicating the exact delivery point. This is the same information that was encoded in the POSTNET barcode, which the Intelligent Mail barcode replaces.


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