The Mailbox Transport Services Layer

The Mailbox Transport Service consists of two separate services: the Mailbox Transport Submission service and Mailbox Transport Delivery service. The Mailbox Transport Delivery service receives SMTP messages from the Transport service on the local Mailbox server or on other Mailbox servers, and connects to the local mailbox database using an Exchange remote procedure call (RPC) to deliver the message. The Mailbox Transport Submission service connects to the local mailbox database using RPC to retrieve messages, and submits the messages over SMTP to the Transport service on the local Mailbox server, or on other Mailbox servers.

The tests mapped to this layer monitor the core components and functions of the Mailbox Transport Submission and the Mailbox Transport Delivery services and reports abnormalities. 

Figure 10 : The tests mapped to the Mailbox Transport Services layer