Since you don't see other errors, I'm thinking this is an environment issue.
First - environments
Make sure your call to php artisan queue:listen
(or queue:work
, if applicable) is using the correct environment so the correct database is getting used:
$ php artisan queue:listen --env=YOUR_ENV
Here's a post on setting up queues in Laravel 4 which might be helpful for more information.
Second - namespaces
As you (apparently?) aren't seeing any PHP errors, this is less likely, but another idea:
If your class is namespaced, you may need to use the \
character to get your models, which are in the global namespace.
// From:
$mailing = new Mailing();
// To:
$mailing = new \Mailing();