diff --git a/nixos/modules/mail.nix b/nixos/modules/mail.nix
index 76eadb1..07326d0 100644
--- a/nixos/modules/mail.nix
+++ b/nixos/modules/mail.nix
@@ -65,7 +65,7 @@ in {
         openFirewall = true;
         settings = {
           server = {
-            lookup.default.hostname = "fb04184.mathematik.tu-darmstadt.de"; # Because the DNS PTR of 130.83.2.184 is this and this should be used in SMTP EHLO.
+            hostname = "fb04184.mathematik.tu-darmstadt.de"; # Because the DNS PTR of 130.83.2.184 is this and this should be used in SMTP EHLO.
             listener = {
               "smtp" = {
                 bind = ["[::]:25"];