The United States Postal Service offers address standardization and verification directly on their website for single addresses. In addition, third-party services such as SmartyStreets.com and Address-Validator.net offer address standardization for long lists of addresses in excel or comma separated values format.
Postal address verification is the process whereby the USPS attempts to standardize and verify a postal address. An address is mailable if it exists within the comprehensive list of U.S. addresses. The USPS delivers more than 500 million letters and processes more than 100 thousand address changes every day.
The first step in the authentication process is standardization. The USPS system standardizes postal abbreviations, makes spelling corrections, writes uniform city names and adds missing information to each of its postal addresses. A complete address contains a street address, city, state and ZIP code.
The matching process for single addresses or lists up to 100 addresses with the web service Address-Validator.net. This website taps into all available global address databases and offers a comprehensive validation and cleaning service. For lists of more than 100 addresses, the service charges $0.05 per address with lower costs for extremely large lists, as of 2015. Addresses that have been validated with the USPS are eligible for bulk discounts and minimize delivery delays.