Postal Address Verification (also known as address standardization, address validation, address verification and CASS certification) is the process used to check the validity and deliverability of a physical mailing address. According to the United States Postal Service, an address is valid (or mailable) if it is CASS-Certified. This means that it exists within the comprehensive list of mailable addresses in their Address Management System.
Therefore, we use the services of a CASS licensee http://smartystreets.com/ to check all our records that contain postal address details are regularly cleansed.
Once an address has been cleansed and verified as mailable, you can be nearly 100% sure that it will be delivered as expected. Correct address information allows you to be confident that mailings are going to the correct destination which will prompt higher response rates from prospects as well prevent you wasting your time and money mailing to undeliverable addresses.
Please see the home page for details of the number of records in the Directory that are Cass Certified.
Read more about Cass Certification at http://en.wikipedia.org/wiki/Postal_address_verification