>>11
Messages are delivered asynchronously. This implies that they are queued. That in turn suggests that these queues are unbounded in size, so that if the receiving process doesn't get enough processor time to handle messages as they come, the queue will grow and grow and grow.
In practice though, I hope there's some sort of a backstop. Me, I like synchronous messaging, or alternatively send-and-wait messaging where you can do something before the "wait" part.