notifications.php

<?php return 
[
  'from' => env('NOTIFICATION_FROM_EMAIL', 'default-email@example.com'),  
];

Notifier.php

<?php

class Notifier {
  
  protected $from;

  public function __construt($fromEmail) {
    $this->from = $fromEmail;
  }
  
  
}

NotifierServiceProvider.php

<?php

class NotifierServiceProvider extends ServiceProvider {
  
  public function register() {
    $this->app->bind(Notifier::class, function($app) {
      return new Notifier($app['config']->get('notifier.from'));
    });
  }
  
}