diff --git a/nixbld-etc-nixos/configuration.nix b/nixbld-etc-nixos/configuration.nix
index 6f3af3a0..db1c2e92 100644
--- a/nixbld-etc-nixos/configuration.nix
+++ b/nixbld-etc-nixos/configuration.nix
@@ -740,7 +740,7 @@ in
 
       mailer = {
         ENABLED = true;
-        HOST = "mail.m-labs.hk:587";
+        SMTP_ADDR = "mail.m-labs.hk:587";
         FROM = "sysop@m-labs.hk";
         USER = "sysop@m-labs.hk";
       };