The figure show three sets of replicated instances of Messaging Server. Each set of replicated services is connected to the network thorough a load balancer.
The leftmost set of replicated services shows two physical servers, each with an instance of Messaging Server MMP.
The middle set of replicated services shows two physical servers, each with an instance of Messaging Server Inbound MTA.
The rightmost set of replicated services shows two physical servers, each with an instance of Messaging Server Inbound MTA.