Preview Notifications (Email) in Browser Laravel 5.4

web.php

Route::get('/preview-mail', function () {
    $user = User::first();
    $mail = (new \App\Notifications\Api\Registration($user))->toMail('random@domain.com');

    $markdown = new \Illuminate\Mail\Markdown(view(), config('mail.markdown'));
    return $markdown->render('vendor.notifications.email', $mail->toArray());
});