Add digest e-mails

config/application.rb

@@ -49,12 +49,5 @@ module Mastodon
       Doorkeeper::AuthorizedApplicationsController.layout 'admin'
       Doorkeeper::Application.send :include, ApplicationExtension
     end
-
-    config.action_dispatch.default_headers = {
-      'Server'                 => 'Mastodon',
-      'X-Frame-Options'        => 'DENY',
-      'X-Content-Type-Options' => 'nosniff',
-      'X-XSS-Protection'       => '1; mode=block',
-    }
   end
 end