mailer.php

<?php

$this->app->singleton('mailer', function ($app) {
    $config = $app->make('config')->get('mail');

    $mailer = new Mailer(
        $app['view'], $app['swift.mailer'], $app['events']
    );

    if ($app->bound('queue')) {
        $mailer->setQueue($app['queue']);
    }

    // ...

    return $mailer;
});