The Enhanced Carrier Route (ECR) subclass Automation Basic rate for letters is not available for all 5-digit ZIP Codes. If a local post office has Carrier Route automation equipment, the Automation Basic rate is NOT available to mailers. Only when a local post office does not have the automation equipment is the lower rate offered to mailers. This is documented in the USPS Quick Service Guide, page 75.

This section pertains to Enhanced Carrier Route Automation Letters. The exception is shown at the bottom of page 75 entitled "Carrier Route rates limited to 5-digit ZIP Codes identified in the City State file." We receive a new City State file from the USPS every 30 days. If you feel it is in error contact your local post office.