Obtaining a Mailer ID from the USPS
Learn how to obtain a Mailer ID from the USPS to be used with Connect+ Series/SendPro P-Series meters, SendPro C400, SendPro C Lite, SendPro C, SendPro+, SendPro C Auto.
Products affected: Connect+® 500W, Connect+® 1000, Connect+® 2000, Connect+® 3000, SendPro™ P1000, SendPro™ P1500, SendPro™ P2000, SendPro™ P3000, SendPro® C400, SendPro C Lite, SendPro C, SendPro+, SendPro C Auto
A mailer ID is a 9-digit number that is required when using Electronic Return Receipt (ERR).
To get a Mailer ID from USPS, visit the USPS Business Customer Gateway Mailer ID page. A Mailer ID is a unique number used to identify your business in USPS mailing systems. The page explains what a Mailer ID is, why it's needed, and how to apply. If you're new to this, it also guides you through setting up an account and submitting your request.
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UPDATED: August 29, 2025