diff --git a/lass/2configs/exim-smarthost.nix b/lass/2configs/exim-smarthost.nix
index 360d839db..3353cdac0 100644
--- a/lass/2configs/exim-smarthost.nix
+++ b/lass/2configs/exim-smarthost.nix
@@ -8,6 +8,7 @@ with import <stockholm/lib>;
     dkim = [
       { domain = "lassul.us"; }
     ];
+    primary_hostname = "lassul.us";
     sender_domains = [
       "lassul.us"
       "aidsballs.de"