The USPS provides free Early Warning System (EWS) data to prevent matching errors due to the age of the address information in the GSDFILxx datasets. The USPS creates a new EWS dataset each week that you can download from the USPS Website (https://postalpro.usps.com/cass/EWS).
The USPS requires EWS files for CASS processing. You can use the GSDFILxx datasets on the GeoStan Geocoding Suite installation for 135 days, but after 105 days you cannot create a CASS report.
When you download the EWS file, ensure it is uploaded in TEXT mode to the mainframe as RECFM=FB LRECL=87, and ensure the JCL uses DDNAME //EWSFILE.