If a file has a filename ending in an extension which appears on the inclusion list, vscan will request a scan from one of the Scan Engines which has registered with it. However, if the extension of the filename for that file also appears on the exclusion list, vscan will not request a scan from one of the Scan Engines which has registered with it. Many administrators exclude files by extension at the NetApp Filer to conserve network bandwidth.

At the Symantec Scan Engine, Scan Engine performs true file typing before it applies exclusions by either file extension or MIME type. To do so, it must receive the entirety of the file, before it attempts to determine the file's true type.