Validate_Email

<!-- jQuery: Validating an email. -->
$('#txtEmail').blur(function(e) {
            var sEmail = $('#txtEmail').val();
            if ($.trim(sEmail).length == 0) {
                alert('Please enter valid email address');
                e.preventDefault();
            }        
            var filter = /^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]
                             {2,4}|[0-9]{1,3})(\]?)$/;        
            if (filter.test(sEmail)) {
                alert('Valid Email');
            }
            else {
                alert('Invalid Email');
                e.preventDefault();
            }
        });
<!-- HTML: Validating an email-->
<asp:TextBox id="txtEmail" runat="server" />