diff --git a/selfprivacy-module.nix b/selfprivacy-module.nix
index 3c6dd68..18b1579 100644
--- a/selfprivacy-module.nix
+++ b/selfprivacy-module.nix
@@ -195,11 +195,11 @@ with lib;
         types.submodule (
           { ... }: {
             options = {
-              domain = mkOption {
+              subdomain = mkOption {
                 type = with types; strMatching "[A-Za-z0-9][A-Za-z0-9\-]{0,61}[A-Za-z0-9]";
-                example = "myservice.example.net";
+                example = "myservice";
                 default = config.sp.domain;
-                description = "Domain to send emails from";
+                description = "Subdomain to send emails from";
               };
 
               systemdTargets = mkOption {
diff --git a/sp-modules/simple-nixos-mailserver/config.nix b/sp-modules/simple-nixos-mailserver/config.nix
index 7425ea9..747bf5f 100644
--- a/sp-modules/simple-nixos-mailserver/config.nix
+++ b/sp-modules/simple-nixos-mailserver/config.nix
@@ -23,7 +23,7 @@ let
       inherit (value) hashedPasswordFile sendOnly;
     }
   ) sp.email;
-  extraDomains = lib.mapAttrsToList (_: value: value.domain) sp.email;
+  extraDomains = lib.mapAttrsToList (_: value: "${value.subdomain}.${sp.domain}") sp.email;
   extraTargets = lib.mapAttrsToList (_: value: value.systemdTargets) sp.email;
 in
 lib.mkIf sp.modules.simple-nixos-mailserver.enable (