Frequently Asked Questions

Click on a frequently asked question below to learn more about the Intelligent Mail® package barcode or download the PDF.

What is the Intelligent Mail® package barcode (IMpb)?

The Intelligent Mail package barcode is a new barcode format designed by the U.S. Postal Service® (USPS) for all commercial and online consumers. The IMpb is required, meaning all FedEx SmartPost® packages must adhere to the IMpb specifications.


When will FedEx be able to process the IMpb format?

FedEx will be able to accept IMpb labels after February 1, 2012.


When will all customers need to begin producing IMpb labels?

The USPS has stated they will finalize the implementation of the Intelligent Mail package barcode effective January 28, 2013. However, FedEx is working with the USPS to ensure our customers have enough time to make the transition to become IMpb compliant. More information will follow regarding the transition timeline.


Is the competition required to adopt IMpb?

Yes, all shipping providers using the USPS will be required to use the IMpb format.


What IMpb data construct is FedEx using?

Commercial mailers have the option of choosing from 9 different constructs. Primarily, the constructs vary based on whether they contain a 6- or 9- digit mailer ID; a 7-, 10-, 11- or 14-digit serial number; and if it includes the ZIP code or not. FedEx SmartPost is utilizing data construct C03.


What is the difference between the current barcode and the IMpb?

There are three main differences in the IMpb:

  1. Application Identifier change
    1. Current barcode has an application identifier of 91
    2. IMpb has a channel-specific application identifier of 92
  2. Moving from a 2-digit USPS service type code to a 3-digit USPS service type code
    1. A 3-digit service type code will provide more intelligence within the barcode as to mail class, sub-class and special services.
    2. A list of service type codes FedEx SmartPost will accept will be provided with the IMpb label specification.
  3. Moving from an 8-digit unique serial number to a 7-digit unique serial number


Will the IMpb result in duplication of tracking numbers for shippers because of the reduction of unique serial numbers?

No. The IMpb allows for 10 million unique tracking numbers within each mail class. For example, a customer who ships via FedEx SmartPost® Bound Printed Matter and Parcel Select® can use 10 million tracking numbers for FedEx SmartPost Bound Printed Matter and another 10 million for Parcel Select without the risk of duplication. Tracking numbers will remain unique for six months, after which shippers can reuse those numbers (as they do today).


Why was the ZIP code and application identifier of “420” removed from the IMpb label?

The USPS has decided to eliminate the ZIP code and application identifier of “420” from the human readable portion of the label only. This information is still embedded within the actual barcode.


Why doesn’t FedEx SmartPost accept 6-digit Mailer IDs (MIDs)?

To maintain consistency, FedEx SmartPost requires the use of a 9-digit mailer ID by all customers. Currently, all FedEx SmartPost customers are on a 9-digit MID. FedEx SmartPost only accepts a 9-digit MID and does not accept a 6-digit MID.


I use the barcode internally (i.e. inventory management). Do I need to make any changes?

Refer to question #6 to see the differences between the current barcode and the IMpb and make changes as needed.


Why did FedEx SmartPost change the serial number to 7 digits?

The serial number was reduced from 8 digits to 7 digits to offset the 1-digit increase in the IMpb service type code. The USPS moved from a 2-digit service type code to a 3-digit service type code with IMpb. Maintaining the overall length of the barcode minimizes database changes for our customers. The uniqueness of the barcode is a combination of MID, service type code and serial number.


How does the FedEx 1D barcode differ from IMpb?

The FedEx 1D barcode is a FedEx Express and FedEx Ground barcode change. IMpb is a change made to the USPS barcode and should not be confused with FedEx 1D barcode.


Why is the USPS adopting the IMpb format?

The USPS has indicated that IMpb Implementation will:

  • Apply a “single” intelligent barcode to all packages
  • Provide better end-to-end tracking visibility
  • Enhance service performance
  • Better understand the costs associated with handling each product


Does IMpb impact all customers shipping with FedEx SmartPost?

Yes, all customers that currently ship and plan to ship will need to use a compliant IMpb label.

  • Customers using FedEx® electronic shipping solutions will need to upgrade to the most recent version of their platform.
  • Customers on spec based/third-party systems will need to code to the IMpb specifications.
  • FedEx® Compatible Solutions Program providers will need to upgrade to support the IMpb specifications.

For more information, go to


Who can I contact for more information?

Customers can contact their account representative or email


U.S. Postal Service, USPS, Parcel Select and IMpb are registered trademarks of the United States Postal Service. © 2011