Exclude Codes
Exclude Code let you set a Prefix to ignore when automatically matching. Some users and companies put ZZ in front of the Listing of Customers that are no longer useable.
For Folder Connect, to import custom files, go to Folder Settings and click Advanced. In the Exclude Code field enter the code you put before defunct customers, such as zz.
This feature is for convenience. Setting Customers as Inactive is an option to consider.