What is a USPS Mailer ID?

The Mailer ID or Mailers ID is a number created and managed by USPS that uniquely identifies an entity in the creation and distribution of a mail piece. These entities may be a mail owner (the company that requests the mail piece to be produced), a printer, a mail service provider (a lettershop, or mail service bureaus) or a mail transportation company (mail logistics and distribution companies).

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