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In my last post (Intelligent Mail Barcode Dumbed Down), I covered the who, what, when, where and how of the Intelligent Mail barcode. In this post, I’m covering more of the what about the what.

The IMb is a series of 65 vertical bars that encode a string of between 20 and 31 digits, and can be placed on letters either in the address block (e.g. 7/8 inches from the left and 5/8 inches from the bottom on a #10 envelope) or in the barcode clear zone found on the lower right corner of the envelope. Twenty of the digits comprise the tracking code, and the remaining 11 are the routing code. Below, I describe them in greater detail.

The IMb Tracking Code 

The tracking code tells us about the mailer and the mailpiece.  

  • Barcode Identifier (BI): The BI is a required, specific 2-digit identifier assigned by the Postal Service™ and is used primarily to encode the presort identification 

  • Service Type Identifier (STID): The 3-digit STID is assigned by the Postal Service and indicates any combination of services that have been requested for the mailpiece. These services include defining the mailpiece as full service, basic or non-automation. It also is used to determine what the mailer wants the USPS® to do with mail that is found to be “undeliverable as addressed” (UAA), as well as the form of address correction that a mailer desires, if any. The USPS provides an STID chart here

  • Mailer ID (MID): The MID is assigned by the Postal Service is a 6 or 9-digit number that uniquely identifies a business or customer. Its length depends on the volume of mail business/customer sends out. 

  • Serial Number:  These 6 or 9-digit numbers are either mailer or postal produced. Serial numbers can be unique to a user’s entire mailing or unique to the individual mailpiece. Every IMb, other than those with an Origin IMb Tracing barcode, must include a serial number. The serial number can also be referred to as a Sequence Number. 

The IMb Routing Code

The routing code includes carrier route and delivery information. It is 0, 5, 9 or 11 digits depending upon the amount of information included by the mailer.

  • No information: zero digits.
  • When the 5 or 9-digit ZIP code is known or included in the IMb, the routing code is 5 or 9 digits.
  • A two-digit delivery point code can be included along with the 9-digit ZIP code when appropriate, bringing the digits in the routing code to eleven, digits that is. A delivery point code is based on what’s called the “secondary address value” or, more simply, an apartment or suite number.

How to Read the Intelligent Mail barcode Guide

Tension has prepared an easy-to-read overview of how to read the IMb, available to you. Click here to download.

Sixty-five bars. Thirty-one digits. Ten pieces of information that can uniquely identify a piece of mail. When more than 150 billion pieces of mail are processed by the USPS each year, it’s one way to stand out.

Disclaimer: All approvals must come from the USPS®. The information presented here is for illustrative purposes only.