mailboxes: be explicit about what is exported

src/views/email.js

@@ -449,7 +449,18 @@ angular.module('Application').controller('EmailController', ['$scope', '$locatio
                 return console.error('Failed to list mailboxes.', error);
             }
 
-            var file = new Blob([ JSON.stringify(result, null, 2) ], { type: 'application/json' });
+            var content = JSON.stringify(result.map(function (mailbox) {
+                return {
+                    name: mailbox.name,
+                    domain: mailbox.domain,
+                    ownerId: mailbox.ownerId,
+                    ownerType: mailbox.ownerType,
+                    active: mailbox.ative,
+                    aliases: mailbox.aliases
+                };
+            }), null, 2);
+
+            var file = new Blob([ content ], { type: 'application/json' });
             var a = document.createElement('a');
             a.href = URL.createObjectURL(file);
             a.download = $scope.domain.domain.replaceAll('.','_') + '-mailboxes.json';