diff --git a/nix/nixos-module/container/upstream.nix b/nix/nixos-module/container/upstream.nix
index f0b530e..d37bb14 100644
--- a/nix/nixos-module/container/upstream.nix
+++ b/nix/nixos-module/container/upstream.nix
@@ -77,7 +77,9 @@ in
       iptables -N fwd_smtp || \
         iptables -F fwd_smtp
       iptables -A fwd_smtp --source ${config.site.net.serv.subnet4} -j RETURN
+      iptables -A fwd_smtp --dest ${config.site.net.serv.subnet4} -j RETURN
       iptables -A fwd_smtp --source ${config.site.net.flpk.subnet4} -j RETURN
+      iptables -A fwd_smtp --dest ${config.site.net.flpk.subnet4} -j RETURN
       iptables -A fwd_smtp -j REJECT
       iptables -I FORWARD -p tcp --dport 25 -j fwd_smtp