Thanks to https://gist.github.com/croessner/64ae8150b3fa3636ec002b812c4ab2ff

data/conf/nginx/site.conf

@@ -24,10 +24,15 @@ server {
 			fastcgi_param PATH_INFO $fastcgi_path_info;
 		}
 
+		rewrite ^(/save.+)$ /rspamd$1 last;
 		location /rspamd/ {
 			proxy_pass       http://rspamd:11334/;
 		    proxy_set_header Host      $host;
 		    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+			add_header Strict-Transport-Security "max-age=31536000; includeSubdomains";
+			add_header X-Content-Type-Options nosniff;
+			add_header X-Frame-Options SAMEORIGIN;
+			add_header X-XSS-Protection "1; mode=block";
 		}
 
         location ^~ /inc/init.sql {

docker-compose.yml

@@ -55,7 +55,6 @@ services:
       restart: always
       dns: 
         - 172.22.1.2
-        - 127.0.0.11
       dns_search: mailcow-network
       networks:
         mailcow-network:
@@ -155,7 +154,6 @@ services:
       hostname: ${MAILCOW_HOSTNAME}
       dns: 
         - 172.22.1.2
-        - 127.0.0.11
       dns_search: mailcow-network
       networks:
         mailcow-network: