diff --git a/nixbld-etc-nixos/configuration.nix b/nixbld-etc-nixos/configuration.nix
index 5aacd896..161de034 100644
--- a/nixbld-etc-nixos/configuration.nix
+++ b/nixbld-etc-nixos/configuration.nix
@@ -1158,6 +1158,7 @@ in
     enablePop3 = true;
     enablePop3Ssl = true;
     certificateScheme = "acme-nginx";
+    rejectSender = [ "sapcloudsupport@alerts.ondemand.com" ];
   } // (import /etc/nixos/secret/email_settings.nix);
   services.roundcube = {
     enable = true;