The Mailbox Transport service is stateless, and does not queue any messages locally. For outgoing messages, 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.
If you would like to read the other parts in this article series please go to:Īs explained in the previous articles of this series, this service runs on all Client Access servers and acts as a stateless proxy for all inbound and outbound external SMTP traffic.įor outgoing messages, the Transport service on Mailbox servers uses Send connectors to communicate with the Front End Transport service.