To follow the flow of messages in an Exchange 2007 environment with all of the various server roles, the following flow occurs:

1.  An incoming message from the Internet first goes to the Edge Transport server.

2.  The Edge Transport server performs first-level recipient validation as well as spam and virus filtering. The message is then passed on to the Hub Transport server.

3.  The Hub Transport server performs compliance content assessment and then looks at the internal routing for messages and forwards the message to another Hub Transport server or directly to a Mailbox server.

4.  The Mailbox server places the incoming message into the user’s mailbox and noti   fies the user that a message has arrived.

5.  The user launches Outlook, OWA, their Windows Mobile device, or another client system and connects to the Client Access server. The Client Access server confirms the destination point of the user’s mailbox and provides the user access to their mailbox data.

6.  In parallel, if a voice mail message comes in for a user, the Unified Messaging server processes the incoming voice message, and then takes the message and places the voice message into the user’s mailbox residing on the Mailbox server for the recipient.