MSMQ, WCF and IIS: Getting them to play nice - Part 2

Welcome back! In Part 1 of this tale, we'd successfully configured a WCF client and an IIS-hosted service to communicate via MSMQ on the same machine. But we're only half done. As you may recall, our goal here is to deploy the client, service and queues all on separate machines. We also want to secure the configuration so that only or client is permitted to send messages to the queue.