src/Notifications/NotificationServiceProvider.php
public function register()
    {
        parent::register();

        $this->app->make(ChannelManager::class)->extend('mail', function () {
            return $this->app->make(Channels\MailChannel::class);
        });
    }
public function register()
    {
        parent::register();

        $this->app->make(ChannelManager::class)->extend('mail', function () {
            return $this->app->make(Channels\MailChannel::class);
        });
    }
Register the service provider.

@return void