mail: add ipv6 rdns check

(cherry picked from commit 6fcfa6cac0)

dashboard/public/views/email.js

@@ -45,11 +45,12 @@ angular.module('Application').controller('EmailController', ['$scope', '$locatio
     $scope.storageQuotaTicks = [ 500*1000*1000, 5*1000*1000*1000, 15*1000*1000*1000, 50*1000*1000*1000, 100*1000*1000*1000 ];
 
     $scope.expectedDnsRecords = {
-        mx: { },
-        dkim: { },
-        spf: { },
-        dmarc: { },
-        ptr: { }
+        mx: {},
+        dkim: {},
+        spf: {},
+        dmarc: {},
+        ptr4: {},
+        ptr6: {}
     };
 
     $scope.expectedDnsRecordsTypes = [
@@ -57,7 +58,9 @@ angular.module('Application').controller('EmailController', ['$scope', '$locatio
         { name: 'DKIM', value: 'dkim' },
         { name: 'SPF', value: 'spf' },
         { name: 'DMARC', value: 'dmarc' },
-        { name: 'PTR', value: 'ptr' }
+        { name: 'PTR4', value: 'ptr4' },
+        { name: 'PTR6', value: 'ptr6' }
+
     ];
 
     $scope.openSubscriptionSetup = function () {