Error in use of Asynchronous Action (Async)

This action should send an email Asynchronously, everything very simple until then, even use the same class in other projects with the same version of MVC. But to my surprise, this project does not work. You simply see the error below.

Error:

  

The asynchronous action method 'EsqueciMinhaSenha' returns to   Task, which can not be executed synchronously.

Stacktrace:

  

at   System.Web.Mvc.Async.TaskAsyncActionDescriptor.Execute (ControllerContext   controllerContext, IDictionary 2 parameters) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary 2   parameters) at   System.Web.Mvc.ControllerActionInvoker. < > c__DisplayClass15.b__12 ()   at   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter (IActionFilter   filter, ActionExecutingContext preContext, Func'1 continuation) at   System.Web.Mvc.ControllerActionInvoker.