diff --git a/nixbld-etc-nixos/configuration.nix b/nixbld-etc-nixos/configuration.nix
index d1b122c4..d540969a 100644
--- a/nixbld-etc-nixos/configuration.nix
+++ b/nixbld-etc-nixos/configuration.nix
@@ -851,14 +851,11 @@ in
   mailserver = {
     enable = true;
     localDnsResolver = false;  # conflicts with dnsmasq
-    # Some mail servers do reverse DNS lookups to filter spam.
-    # Getting a proper reverse DNS record from ISP is difficult, so use whatever already exists.
-    fqdn = "42-200-147-171.static.imsbiz.com";
-    domains = [ "nmigen.org" ];
+    fqdn = "mail.m-labs.hk";
+    domains = [ "m-labs.hk" ];
     loginAccounts = (import /etc/nixos/secret/email_accounts.nix);
     certificateScheme = 3;
   };
-  security.acme.certs."${config.mailserver.fqdn}".extraDomainNames = [ "mail.nmigen.org" ];
 
   system.stateVersion = "21.05";
 }