What is a system-resource monitoring feature of the Microsoft Exchange Transport service?

The system-resource monitoring feature of the Microsoft Exchange Transport service is back pressure. This feature plays a critical role in maintaining the health and performance of the Exchange server. Back pressure is implemented to prevent the server from being overwhelmed by too much message traffic, thereby ensuring that the system remains stable and responsive.

When the Exchange server detects that resources such as memory, CPU, or disk space are being consumed at an unsustainable level, back pressure will intervene. It does this by temporarily limiting the acceptance of new messages into the transport queue until the server’s resource usage falls back to normal levels. This mechanism helps to protect the system from outages and degradation that can occur when resource thresholds are exceeded.

In contrast, while options like load balancer, queue management, and message tracking all play important roles in the functioning of the Exchange server, they don't serve the specific purpose of monitoring system resources and managing the flow of email traffic based on resource availability. Load balancers distribute workloads across multiple servers; queue management involves sorting and handling messages in the queue; and message tracking provides insights into the status and flow of messages, none of which directly equate to the monitoring and management of critical system resources like back pressure does.