ASP.NET: Email Validation by RegularExpressionValidator

<form id="form1" runat="server">
    <div>
        <asp:Label id="lblEmail" Text="Email Address:" AssociatedControlID="txtEmail" Runat="server" />
        <asp:TextBox id="txtEmail" Runat="server" />
        <asp:RegularExpressionValidator
            id="regEmail"
            ControlToValidate="txtEmail"
            Text="(Invalid email)"
            ValidationExpression="\w+([-+.’]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"
            Runat="server"
        />
        <br /><br />
        <asp:Button id="btnSubmit" Text="Submit" Runat="server" />
    </div>
</form>