A. The Microsoft Exchange Server 2003 Load Simulator (LoadSim), which you can download at http://www.microsoft.com/downloads/details.aspx?FamilyID=92EB2EDC-3433-47CA-A5F8-0483C7DDEA85&displaylang=en , lets you simulate the performance load of a number of Messaging API (MAPI) clients. After you download the tool, extract and run loadsim.msi. Don't install the tool on the Exchange server; install it on a client that has Microsoft Office Outlook 2003 installed. The download includes a document that describes how to use and monitor the tool