diff --git a/hosts/servers/mail-01.nix b/hosts/servers/mail-01.nix
index 2aa5eb9..32cc880 100644
--- a/hosts/servers/mail-01.nix
+++ b/hosts/servers/mail-01.nix
@@ -63,6 +63,7 @@ in
 
   services.postfix = {
     config = {
+      inet_protocols = "ipv4";
       smtp_bind_address = floatingIPv4;
 
       mydestination = lib.mkForce [