function checkemail(f) {
   if (f.email.value == "") {
      chnecell(geenemail);
      f.email.focus();
      return (false);
   }
   if (f.email.value.length < 1) {
      chnecell(geenemail);
      f.email.focus();
      return (false);
   }
   var x = f.email.value;
   var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
   if (!filter.test(x)) {
      chnecell(foutemail);
      f.email.select();
      return (false);
   }
   if (document.getElementById('smbut')) {
      document.getElementById('smbut').style.visibility = 'hidden';
   }
   return (true);
}