Front-end servers may start rapidly establishing Transmission Control Protocol (TCP) connections to themselves that are kept open indefinitely. After you stop all client connections to the front-end server, the connections still remain open.
This issue can occur if the information stores have been removed from a front-end server that also functions as an Simple Mail Transfer Protocol (SMTP) bridgehead server. Although it is recommended that you delete the information stores on front-end servers, if you have a front-end server that also functions as a SMTP bridgehead server, the information store process must be running so that the front-end server can generate delivery status notifications. The store generates delivery status notification code; therefore, on SMTP bridgehead servers, at least one private information store needs to be mounted and running. The root cause of open connections has not yet been determined. Some customers use front-end servers as SMTP bridgehead servers.
The Inetinfo.exe process may create those connections. Inetinfo may also consume all available resources by taking 100 percent of the central processing unit (CPU) time and leaving no available memory
Microsoft has confirmed that this is a problem in Microsoft Exchange 2000 Server.