Message Transfer Features in Exchange Server
Message Transfer Features in Exchange Server
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Both message flow through a Microsoft® Exchange server and the routing of messages to other Exchange servers and messaging systems have been considerably redesigned, starting with Exchange 2000 Server. The underlying Exchange architecture has also changed to support the new network-based paradigm of Microsoft Windows® 2000 and Exchange Server. Some of these changes do not directly affect the way a gateway is designed, but do influence its administration. It is also important for gateway developers to be aware of the several changes that do affect both gateway design and maintenance.
A complete description of the changes to message transfer is beyond the scope of this document, but the table below presents a summary of the differences between Exchange Server 5.5 and Exchange Server 2003 features that affect message transfer. This table highlights the changes that are most important to the development of gateways.
| Feature | Exchange 5.5 | Exchange Server 2003 | Comments |
| Operating System | Integrated with Microsoft Windows NT® 4.0. | Embedded in Windows 2000. | Exchange Server 2003 uses the same messaging terminology as Windows 2000. Microsoft Active Directory® stores all gateway configuration information. |
| Integration with the Internet | Internet protocols are built into the Information Store to ensure the browser rapid access to messages. | Internet protocols have been removed from the store. Microsoft Internet Information Services (IIS) now contains Internet protocols and also performs routing calculations in its SMTP transport core, which includes a categorizer and a routing engine. | IIS is a service of Windows 2000. There is rapid communication between IIS and the store through the new Exchange queuing layer, EXIPC. |
| Message Routing | The message transfer agent (MTA) determines message routes using the Gateway Address Routing Table (GWART), which is relatively static. | Routing is determined through dynamic link-state information that the routing engine obtains from Active Directory. | All configuration information is stored in Active Directory. There is no static GWART in Exchange Server 2003. No update is required when a new address type is added to a gateway. |
| Storage | Single Information Store with a single database. | Up to four storage groups in the store, each consisting of up to five databases, on a single Exchange server. | The architecture allows for more storage groups and databases per storage group in future implementations of Exchange. |
| Connectivity | X.400-based MTA supports a variety of connectors. | SMTP is the native transport and is a routing peer to X.400. | The MTA still exists to support foreign connectors that use the X.400 protocol and EDK gateways. The MTA no longer performs routing. |
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This topic last updated: March 2006
Build: June 2007 (2007.618.1)
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