You have indicated that users may be running third party applications or devices that synchronize with the server. Some applications ...

You have indicated that users may be running third party applications or devices that synchronize with the server. Some applications that access the Exchange server are require a lot of resources on the server because they issue a large number of requests, or they issue resource-intensive requests. If the load on the messaging server it too high, it can cause performance problems. If server RPC load has increased recently, you may want to investigate third party add-ins or programs that synchronize e-mail as the source of increased load. If you are unable to reduce the load on your server, and your server is beyond capacity, you may need to move some users to another server.