diff --git a/sp-modules/simple-nixos-mailserver/config.nix b/sp-modules/simple-nixos-mailserver/config.nix
index a969f36..b3de78f 100644
--- a/sp-modules/simple-nixos-mailserver/config.nix
+++ b/sp-modules/simple-nixos-mailserver/config.nix
@@ -75,7 +75,9 @@ lib.mkIf sp.modules.simple-nixos-mailserver.enable
       "admin@${sp.domain}" = "${sp.username}@${sp.domain}";
     };
 
-    certificateScheme = "acme";
+    certificateScheme = "manual";
+    certificateFile = "/var/lib/acme/root-${cfg.domain}/fullchain.pem";
+    keyFile = "/var/lib/acme/root-${cfg.domain}/key.pem";
 
     # Enable IMAP and POP3
     enableImap = true;