NVC scans all in- and outgoing emails as well as postings to and from newsgroups to ensure that they do not contain malware of any kind. In addition, attachments can be blocked based on file extension or specific file name to further increase security. The email scanning feature works with most email programs currently available. On-access scanning involves constant monitoring of the file system on the workstations. For antivirus software, it is imperative to detect and block a computer virus before it is activated. Whenever a file is accessed in a read/write operation, or a program is executed, the on-access scanner is notified and scans the file automatically.