diff --git a/app/Livewire/Ui/System/SettingsForm.php b/app/Livewire/Ui/System/SettingsForm.php
index 8fd461c..d54b5cc 100644
--- a/app/Livewire/Ui/System/SettingsForm.php
+++ b/app/Livewire/Ui/System/SettingsForm.php
@@ -216,6 +216,8 @@ class SettingsForm extends Component
             $this->applyDomains(false);
         }
 
+        $this->syncSysmailDomain();
+
         $this->loadSslStatus();
 
         $this->dispatch('toast', type: 'done', badge: 'Domains',
@@ -223,6 +225,39 @@ class SettingsForm extends Component
             text: 'Konfiguration wurde übernommen.', duration: 4000);
     }
 
+    private function syncSysmailDomain(): void
+    {
+        $platformBase = strtolower(config('mailpool.platform_zone', env('BASE_DOMAIN', '')));
+        if (!$platformBase || $platformBase === 'example.com') return;
+
+        $systemSub  = strtolower(config('mailpool.platform_system_zone', 'sysmail'));
+        $expectedFqdn = "{$systemSub}.{$platformBase}";
+
+        // Bestehende System-Domain suchen (is_system=true, nicht is_server)
+        $existing = \App\Models\Domain::where('is_system', true)
+            ->where(fn($q) => $q->whereNull('is_server')->orWhere('is_server', false))
+            ->first();
+
+        // Alles passt → nichts tun
+        if ($existing && $existing->domain === $expectedFqdn) return;
+
+        // Alte System-Domain + Postfächer löschen falls Domain geändert
+        if ($existing && $existing->domain !== $expectedFqdn) {
+            \App\Models\MailUser::where('domain_id', $existing->id)->forceDelete();
+            $existing->forceDelete();
+        }
+
+        // Neu anlegen via Seeder
+        try {
+            Artisan::call('db:seed', [
+                '--class' => 'Database\\Seeders\\SystemDomainSeeder',
+                '--force' => true,
+            ]);
+        } catch (\Throwable $e) {
+            \Illuminate\Support\Facades\Log::error('SystemDomainSeeder failed', ['error' => $e->getMessage()]);
+        }
+    }
+
     private function cleanDomain(string $value): string
     {
         $value = trim($value);