.formRed {-webkit-box-shadow:inset 0px 0px 10px rgba(255,0,0,0.8);-moz-box-shadow:inset 0px 0px 10px rgba(255,0,0,0.8);box-shadow:inset 0px 0px 10px rgba(255,0,0,0.8);}  
  .formGreen {-webkit-box-shadow:inset 0px 0px 10px rgba(0,255,0,0.8);-moz-box-shadow:inset 0px 0px 10px rgba(0,255,0,0.8);box-shadow:inset 0px 0px 10px rgba(0,255,0,0.8);}

<script type="text/javascript">  
  var regV = /^((?:(?:(?:\w[\.\-]?)*)\w)+)\@((?:(?:(?:\w[\.\-\+]?){1,20})\w)+)\.(\w{2})$/;  
  $('input[name=email]').keyup(function() {  
  var rRegV = $(this).val().search(regV);  
  if(rRegV == -1 && $(this).val().length > 0) {  
  $(this).addClass('formRed');  
  }  
  else if($(this).val().length > 0) {  
  $(this).addClass('formGreen');  
  }  
  else {  
  $(this).removeClass('formRed formGreen');  
  }  
  });  
  </script>