jquery判断邮箱格式问题

var search_str = /^[\w\-\.]+@[\w\-\.]+(\.\w+)+$/;
var email_val = $("#Email").val();
if(!search_str.test(email_val)){
alert("please input right email !");
$('#Email').focus();
return false;
}

ar mail = $('#mail').val();
if (mail != '') {//判断
var reg = /^([a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+((\.[a-zA-Z0-9_-]{2,3}){1,2})$/;
if (!reg.test(mail)) {
alert('邮箱格式不正确，请重新填写!');
return false;
}
}

<script src="/js/jquery-1.4.2.js" type="text/javascript"></script>
<script language="javascript">$(document).ready(function() {
$('.error').hide();
$('.submit').click(function(event){
var email=$('.email').val();
if(valid_email(email)) {
$('.error').hide();
} else {
$('.error').show();
event.preventDefault();
}
});
});