This field determines what happens to email messages that have been identified by ClamAV as containing a virus. The available options are :

Throw away
  Any detected viruses will be immediately deleted.
Write to standard virus file ~/mail/virus
  Viruses are written to the standard folder for manual analysis and deletion.
Write to mail file under home directory
  Viruses are saved to the mail file under the user's home directory that you enter. To write to a Maildir format directory, put a / at the end of the filename.
Forward to email address
  Any virus-laden messages will be forwarded to the entered address.
Write to other file
  Viruses will be written to the given mail file (or directory if the path ends with /), which can be anywhere on the server.