What role is primarily responsible for directing mail traffic in Exchange Server?

The Transport Server Role is primarily responsible for directing mail traffic in Microsoft Exchange Server. This component manages the routing and delivery of email messages through the various Exchange servers within the organization and to external destinations.

The Transport Server Role handles multiple essential functions, including message queuing, routing decisions, and SMTP (Simple Mail Transfer Protocol) processing, ensuring that emails are efficiently delivered to their intended recipients. It also facilitates the handling of mail flow within the organization's infrastructure and across the internet.

In contrast, while the Client Access Server Role focuses on client connectivity for accessing mailboxes and services within Exchange, and the Mailbox Server Role primarily stores user mailboxes and manages database operations, these roles do not handle the routing and directing of mail traffic as the Transport Server does. The Edge Transport Server Role, while also involved in mail flow, primarily functions at the network perimeter for security and anti-spam purposes, and it is specifically designed to provide additional features, but it works in conjunction with the Transport role rather than being the main component responsible for overall mail traffic direction.