Using CASS certified software ACT ONE is able to offer you Address Standardization, Zip+4, Delvery Point Barcode,
Carrier Route, and Line of Travel information for your customer or mailing list.  
This process first standardizes all addresss information (this includes inserting pre/post directionals and using USPS abbreviations) . Then, Zip+4 codes, carrier route codes, and line of travel information are assigned to the file based on valid addres ranges for the input street address.

Please be aware that even though a Zip+4 code has been assigned to your list, it is possible that the address could still be undeliverable.  For a precise deliverability confirmation, or DSF service should be used instead of CASS.  
DSF does not use a range match.  It uses an exact match of all delivery elements to determine if an address is truly deliverable.
A CASS report is provided with all Address Standardization.  This report allows you to take advantage of any applicable postage discounts.