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Mailer Identifier (MID)

The Mailer Identifier (MID) is a field within the Intelligent Mail barcode that is used to identify mailers. MIDs are assigned by the USPS® to a Mail Owner, Mailing Agent or other service providers who request them.

MIDs are either a 9-digit or a 6-digit numeric code and are assigned based on annual mail volume criteria. One 9-digit MID is assigned to a business location without a volume requirement.

Who is MID for?

For Intelligent Mail Basic or Full-Service, the MID can be owned by the Mail Owner, Mail Service Provider, or any Stakeholder in the supply chain.

First Class Mail
Standard Mail


An MID has several purposes and is used in Intelligent Mail barcodes in the physical mailing, to identify Mail Preparers and Mail Owners within eDoc and also to determine to whom mailing information and reports should be distributed.

The Mailer ID Service enables you to:

  • Search a CRID that may be tied to your account CRID
  • Request a new MID
  • Add a customer reference or nickname for your MID
  • Set up a data distribution profile for acquiring scan data related to Full-Service ACS, IMb Tracing, Full-Service Start-The-Clock/Container Visibility, Tray Visibility, and Bundle Visibility
  • Delegate your profile to be managed either from one account or by someone else
  • Set up an ACS billing and sign up for MID-based eInduction processing

Exception Process
If you need additional MIDs, not obtainable through the Business Customer Gateway-MID Tool, refer to the Mailer ID Exception Process. Mailing Agents who are authorized to obtain MIDs on behalf of Mail Owners, should refer to the Agent Application Process. All forms can be viewed and printed from the Important Links box on this web page. Complete the Mailer ID Application and the Additional Accounts Information sheet if applicable and submit them to the Business Mail Entry Unit (BMEU) or the Mailpiece Design Analyst for processing.

To locate your local Business Mail Entry Unit (BMEU) or Mailpiece Design Analyst (MDA), go to: (BMEU locator)

Program Registration Mailer ID Assignment
For shippers who enroll in Shipping Service programs using the Business Customer Gateway, one 9-digit (master) Mailer ID is initially assigned. Subsequent 9-digits are assigned based on a Mail Owner single business or a mail service provider's single-client business shipping location.


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Related Products

Customer Registration ID (CRID)

The USPS® Customer Registration ID (CRID) is a unique number that identifies a specific business location involved in a mailing. In order to submit electronic documentation (and receive Full-Service benefits), customers must have a customer registration ID assigned to their business location. 

Electronic Documentation (eDoc)

To participate in Full-Service Intelligent Mail®, mailers must submit information electronically. This computer-consumable version replaces existing hardcopies and includes the following: postage statement and qualification report.

OneCode ACS®

OneCode ACS allows customers mailing First-Class Mail®, Standard Mail®, and Periodical flats or letters to receive electronic or automated address corrections using the Intelligent Mail® barcode.


The electronic Induction (eInduction) process simplifies the induction of drop shipments and expedited plant load mailings by leveraging existing eDoc, Intelligent Mail Container barcode (IMcb), and handheld scanner technologies to verify payment and preparation of commercial mail containers.


For questions, please call 1-800-522-9085 or email