\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*

protected string RenderPartialViewToString()
        {
            return RenderPartialViewToString(null, null);
        }

        protected string RenderPartialViewToString(string viewName)
        {
            return RenderPartialViewToString(viewName, null);
        }

        protected string RenderPartialViewToString(object model)
        {
            return RenderPartialViewToString(null, model);
        }

        protected string RenderPartialViewToString(string viewName, object model)
        {
            if (string.IsNullOrEmpty(viewName))
                viewName = ControllerContext.RouteData.GetRequiredString("action");

            ViewData.Model = model;

            using (StringWriter sw = new StringWriter())
            {
                ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(ControllerContext, viewName);
                ViewContext viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
                viewResult.View.Render(viewContext, sw);

                return sw.GetStringBuilder().ToString();
            }
        }