LetterStream offers 2 services (CASS and NCOA) that allow you to submit an address list in .csv format, which takes your entire address list and standardizes it according to the USPS recommendations.
The differences in the products are as follows:
CASS - this option standardizes your address list
NCOA - this option standardizes your address list, as well as checks your recipient's names against the National Change of Address system, which will return the most recently known addresses for your recipients
To learn how to use our address cleanup options, click here.