function validEmail(email)
  {                 
   invalidvalue = " /:,;"     // cannot be empty
   
    for (i=0; i < invalidvalue.length; i++)
    {
      badvalue = invalidvalue.charAt(i)
      if (email.indexOf(badvalue,0) != -1)  // does it contain any invalid characters? 
      { 
        return false
      }
    }
    at = email.indexOf("@",1)
    if (at == -1) {
      return false
    }
    if (email.indexOf("@",at+1) != -1) {    // only one @ symbol
      return false
    }
    dot = email.indexOf(".",at)       //  at least one dot (.) after the @ symbol
    if (dot == -1) {
      return false
    }
    if (dot+3 > email.length) {          // must be at least 2 characters after the dot (.)
      return false
    }
    return true
  }