Microsoft Exchange Server 2003 Load Simulator will simulate the performance load of MAPI clients with this benchmarking tool, which allows you to test how a server running Exchange 2003 responds to e-mail loads. These tests send multiple messaging requests to the Exchange server, thereby causing a mail load. LoadSim is a useful tool for administrators who are sizing servers and validating a deployment plan. Specifically, LoadSim helps you determine if each of your servers can handle the load to which they are intended to carry. Another use for LoadSim is to help validate the overall solution.