I got this error on client webpart project of sharepoint hosted app?

Dear everyone, 

anyone know how to solve this message error, pleas share with me,

function sendEmail() {
    var appweburl = decodeURIComponent(getQueryStringParameter('SPAppWebUrl'));
    var hostweburl = decodeURIComponent(getQueryStringParameter('SPHostUrl'));
    //var urlTemplate = hostweburl + "/_api/SP.Utilities.Utility.SendEmail";
    var urlTemplate = appweburl + "/_api/SP.Utilities.Utility.SendEmail";
    var digest = $("#__REQUESTDIGEST").val();
 //   alert(urlTemplate);
    $.ajax({
        contentType: 'application/json',
        url: urlTemplate,
        type: "POST",
        data: JSON.stringify({
            'properties': {
                '__metadata': { 'type': 'SP.Utilities.EmailProperties' },
                'From': 'tola.dy@domainname.com',
                'To': { 'results': ['tola.dy@domainname.com'] },
                'Body': 'body',
                'Subject': 'subject'
            }
        }
      ),
        headers: {"Accept": "application/json;odata=verbose","content-type": "application/json;odata=verbose",
            // "X-RequestDigest": $("#__REQUESTDIGEST").val()"X-RequestDigest": digest
        },
        success: function (data) {
            //var result = data.d.results;
            //var i = result.length;
            alert('success');
        },
        error: function (err) {
            alert(JSON.stringify(err));
        }
    });


}

Thank for help...

------------------------------------------------------------ ---Tola---