(default exchange) verifiedWritten by the Hub
The nameless exchange
RabbitMQ's built-in exchange, where a routing key is simply a queue name — which is why MailerQ's routing keys read like queue names.
In detail
rabbitmq-exchange ships empty, so everything the engine publishes goes here and lands in the queue whose name matches the routing key. That is what makes the configuration legible: success means the queue called success. Name a real exchange instead and the same keys become bindings, which is what a customer with their own topology will want — and the point at which rabbitmq-unroutable stops being theoretical.