national change of address (ncoalink) "is a secure dataset of approximately 160 million permanent change-of-address (coa) records consisting of the names and addresses of individuals, families and businesses who have filed a change-of-address with the usps". it is maintained by the united states postal service and access to it is licensed to service providers and made available to mailers. there are six licenses available including full service providers (48 months) and limited service providers (18 months). the use of ncoalink is required in order to obtain bulk mail rates, as it minimizes the number of uaa (undeliverable as addressed) mailpieces saving the mailer money and reducing the usps's processing of this type of mail.