rework of the e2e test suites

app/Http/Controllers/Testing/TestMailboxController.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace App\Http\Controllers\Testing;
+
+use App\Http\Controllers\Controller;
+use App\Testing\Mailbox;
+use Illuminate\Http\JsonResponse;
+
+class TestMailboxController extends Controller
+{
+    public function index(): JsonResponse
+    {
+        abort_unless(app()->environment(['local', 'testing']), 404);
+
+        return response()->json([
+            'data' => Mailbox::all(),
+        ]);
+    }
+
+    public function destroy(): JsonResponse
+    {
+        abort_unless(app()->environment(['local', 'testing']), 404);
+
+        Mailbox::flush();
+
+        return response()->json([
+            'status' => 'ok',
+        ]);
+    }
+}