sender_regexp()
  Sender IP address regexp scanner.
  
  This scanner can be used to scan for sender's IP address. You can use
  it to perform some actions (for example send report to admin) if
  a virus is comming from your local addresses.
  
  Usage: sender_regexp([['VirName', 'RegExp_Pattern...'], ...])
  
  Where: 'VirName' is a string, which identifies defined virus
         'RegExp_Pattern...' is a regexp pattern
    
  Example: sender_regexp([
             ['LOCAL_IP', '(192\.168|172\.(1[6789]|2[0-9]|3[01])|10)\.']
           ])