Notice: This material is excerpted from Special Edition Using Microsoft Exchange Server, ISBN: 0-7897-0687-3. The electronic version of this material has not been through the final proof reading stage that the book goes through before being published in printed form. Some errors may exist here that are corrected before the book is published. This material is provided "as is" without any warranty of any kind.
By coupling the functions of a Gateway Post Office and the External program, the Microsoft Mail Connector bundled within Microsoft Exchange Server becomes the primary link between Microsoft Exchange Server and Microsoft Mail 3.x(PC and Appletalk). It also provides the connectivity link that ties Microsoft Exchange Gateways and MS MAIL 3.X Gateways. This Connector allows Microsoft Exchange Server to route and transfer messages to one or more MS MAIL 3.X(PC) systems over LAN, Asynchronous, or X.25 connections.
You can configure Microsoft Mail Connector for message transfer and routing by using components provided with Microsoft Exchange Server. The components built into the Microsoft Mail Connector are comparable to the components in the MS MAIL 3.X Post OfficePost Office and External message transfer programs. The Microsoft Mail Connector components run as services on a Windows NT operating system, which allows for better error logging, memory management, and performance monitoring of the entire messaging system. Integration of an existing MS MAIL 3.X system, using the External or the Multitasking MTA programs with Microsoft Exchange Server, can be easily configured to allow a common coexistence of both messaging systems on the same LAN.
In this chapter, you learn the following:
Microsoft Mail Connector Components
The following three components are located within Microsoft Mail Connector and work in conjunction with each other transparently to transfer and route messages to and from MS MAIL Post Offices (see fig. 6.1):
The Microsoft Mail Connector Interchange is a Windows NT service that converts the message from or to MS MAIL 3.X format, then routes and transfers messages between Microsoft Exchange Server and the Microsoft Mail Connector Post Office. This process is completely transparent to the users and completed in the background. Configuring the Microsoft Mail Connector Interchange must be done for LAN, asynchronous, and X.25 transport connections. Configuration requires using the Administrator program, in the Interchange tab, to create and setup an Administrator Mailbox to receive delivery status messages, the establishment of a primary language used by the majority of the Post Offices using the Connector, and if MS MAIL 3.X clients wish to view or save OLE documents received from Microsoft Exchange Clients, the Maximize MS MAIL 3.X Compatibility item must be selected.
The Microsoft Mail Connector Post Office is a temporary information store for messages in transit. The Connector Post Office is sometimes referred to as a gateway Post Office because it is dedicated to message transfer and has no local mailboxes. The Microsoft Mail Connector Post Office sits between the Microsoft Mail Connector Interchange and the Microsoft Mail Connector MTA. Since this Post Office works with messages being transferred both ways through its information store, it temporarily holds messages that have been converted and are waiting to be routed to MS MAIL 3.X clients or messages sent from MS MAIL 3.X clients, waiting to be converted. until it is transferred toward its appropriate destination.
The Microsoft Mail Connector Message Transfer Agent is a Windows NT service that connects to and transfers mail between the Microsoft Mail Connector Post Office and one or more MS Mail (PC) Post Offices. It can execute most of the same operations of the MS MAIL 3.X External and Multitasking MTA programs, including message distribution and delivery to users on MS MAIL Post Offices. The MTA contains the information for which the direct and indirect connection routing of mail messages occurs between MS MAIL 3.X Post Offices. The information is read from a list that is configured through the Microsoft Mail Connector section of the Administrator program.
Once again, all of the preceding components can be configured in the Administrator program, under the Microsoft Mail Connector, within the individual component tab.
Microsoft Mail Connectors components.
In an MS MAIL 3.X environment, the External (Mail Transfer Agent --MTA) and the Multitasking MTA (MMTA) programs transfer and route messages between MS MAIL Post Offices. The programs do not have all of the same advanced features as the Microsoft Mail Connector. However, any existing MS MAIL 3.X system using External and the Multitasking MTA programs to transfer and route messages, can easily be integrated with a Microsoft Exchange Server directly, with the help of the Microsoft Mail Connector.
The Microsoft Mail Connector MTA does not completely handle all of the functions of the MS MAIL 3.X External or Multitasking MTA. In some cases, the messaging system may still require some of the functions found in the External program.
For example, when MS MAIL 3.X Remote users dial in for their messages, they dial into the MS MAIL MTA (External), which handles message transfer between Remote users and the MS MAIL 3.X Post OfficePost Offices. With users still using the MS MAIL Remote client program, the MS MAIL MTA (External) cannot be replaced by the Microsoft Mail Connector. The continued use of the External program will need to be maintained, as well as the Microsoft Mail Connector.
Another perspective is when you use the MS MAIL MTA (External); the MTA administers to modem setup and the dial-out process. It also requires its own separate dial-in infrastructure. If other remote applications require dial-out access also, another separate dial-in infrastructure will be needed. This requires quite a bit of communications equipment.
Microsoft Exchange uses Microsoft NT Server's standard remote network hardware that supports standard protocols such as the following:
Microsoft Exchange profits from the use of these standard protocols by making it possible to implement and integrate a single dial-in infrastructure to handle all remote communications services provided by the Microsoft NT Server. A multitude of remote access servers can be used by your Remote mail users to gain access to the mail system. For example, the Microsoft Exchange Client remote users can make use of the built-in Remote Access in Microsoft NT Server. This capability allows remote users to dial directly into Microsoft Mail Connector MTA through the Microsoft Exchange Server.
When both Microsoft Exchange and MS MAIL 3.X Post OfficePost Offices reside on the same LAN, you can configure the Microsoft Mail Connector to transfer route messages from the Microsoft Exchange Server MTA, convert the message, and deliver the message to the correct recipient on the MS MAIL 3.X Post OfficePost Office.
When you send a message to a Microsoft Exchange Server destined for an MS MAIL 3.X recipient located on the same LAN, the message is received by the Microsoft Exchange MTA. Then, the message is routed by the Microsoft Exchange MTA to the Microsoft Mail Connector Interchange. Here, the message and any OLE attachments are converted to MS MAIL 3.x format. The converted message is then sent to the Microsoft Mail Connector Post Office (Information Store) where it is held until the Microsoft Mail Connector MTA picks it up and delivers it to the appropriate MS MAIL 3.X Post OfficePost Office (see fig. 6.2).
The message transfer process from Exchange Server MTA to MS MAIL 3.X.
MS MAIL 3.X message delivery can be performed only over a Direct LAN connection. The Microsoft Mail Connector, External MTA and Multitasking MTA determine their routing information between Microsoft Exchange Server and MS MAIL 3.X by the the information that is entered into the Address Space. The address space is defined as a set of MS MAIL 3.X Post Office names, which mail messages will be routed to by the Microsoft Mail Connector. This entry in the address space is also known as an Instance.
When connecting MS MAIL 3.X over X.25 or Asynchronous services, the External MTA or Multitasking MTA program at the Remote Post Office location will also have to be configured with an instance in the address space of the MTA to connect with the Microsoft Mail Connector (see fig. 6.3).
Basic MS MAIL 3.X External (or Multitasking MTA) layout.
Configuring LAN Connections to existing Post Offices
The LAN connection happens to be the easiest and one of the simplest types of connections in terms of setup and administration. In this particular case, you don't have to use the External or Multitasking MTA programs at all. Instead, you can use the Administrator program in Microsoft Exchange Server to configure the majority of the message routing and transfer between the Microsoft Mail Connector and the MS MAIL 3.X Post OfficePost Offices.
MS MAIL 3.X Post OfficePost Office
If you have multiple MS MAIL 3.X Post OfficePost Offices on the same LAN, a way to increase the performance of the Microsoft Exchange Server is to configure one of the MS MAIL 3.X Post OfficePost Offices as the direct connection Post Office. This MS MAIL 3.X Post Office will be the recipient and sender of messages transferred to and from the Microsoft Exchage Server Microsoft Mail Connector. The Microsoft Mail Connector contains an instance in its address space to route messages to the MS MAIL 3.X direct connection Post Office. Additionally, the address space of the Microsoft Mail Connector also specifies instances for all of the other MS MAIL 3.X Post Offices located on the LAN as indirect connections. The MS MAIL 3.X Post Offices configured as an indirect connections transfer messages to and from the MS MAIL 3.X direct connection Post Office.
Similarly, the address space of the MS MAIL 3.X Post Office that is configured as the direct connection Post Office will also contain entries of indirect connection instances that describe the remaining MS MAIL 3.X Post Offices located on the LAN. MS MAIL 3.X Post OfficePost OfficePost OfficePost OfficeMS MAIL 3.X Post OfficePost Office (see fig. 6.4).
Basic LAN connection with direct and indirect route configuration.
To transfer and route messages correctly, the Microsoft Mail Connector must know about each of the remote Post Offices. Microsoft Mail Connector has an integrated feature that automatically extracts Indirect Routing information from an MS MAIL 3.X Post OfficePost Office. This feature means there is no need to manually configure the routing information for each of the MS MAIL 3.X Post OfficePost Offices connected indirectly to the Microsoft Mail Connector. The only requirement for the automatic upload of routing information is a LAN Connection. Unfortunately, if the MS MAIL 3.X Post OfficePost Office you are trying to connect to is over an Asynchronous or X.25 service, the indirect routing information will have to be input manually through the Microsoft Mail Connector property pages.
Asynchronous and X.25 Connections for Remote Post Offices
You need two components to connect Microsoft Exchange Server and an MS MAIL 3.X Post OfficePost Office over an X.25 or Asynchronous service. The first is the Microsoft Mail Connector MTA, the main routing component of the Microsoft Mail Connector included within the Microsft Exchange Server. It runs as a service on the Microsoft NT Server. When configured, it contains the routing information in the address space that will be used to route messages to and from the MS MAIL 3.X Mail systems.
The second is the MS MAIL 3.X External or Multitasking MTA program provided with MS MAIL 3.X Server. This program provides the message transfer and modem management functions necessary to communicate over a remote connection within an MS MAIL 3.X system. If the MS MAIL 3.X External MTA will reside on a DOS computer, this will need to be dedicated computer. DOS will not allow multiple sessions, or executables, to occur at the same time. Setting up the Multitasking MTA on a Microsoft Windows NT Workstation would allow multiple MTA's to reside and route messages on a single computer. The Multitasking MTA can also reside on a separate Microsoft Windows NT Server if desired. I reccommend using the Microsoft Windows NT Workstation because it doesn't require passwords.
If a Direct Asynchronous or X.25 route is desired, MS MAIL 3.X External or Multitasking MTA must be located on the same LAN as the Post Office (see fig. 6.3).
When a message destined for an MS MAIL 3.X Post OfficePost Office is sent from a Microsoft Exchange client, the message is stored temporarily in the Microsoft Mail Connector Post Office. If the message is not picked up by the Microsoft Mail Connector MTA and routed to its destination, the message will remain in the Connector Post Office until it times out and is returned to the sender, or it gets picked up and delivered by a LAN connected instance of the MS MAIL 3.X External or Multitasking MTA or Gateway (see fig. 6.3)
Using Multiple Microsoft Mail Connectors (PC) MTAs
Each Microsoft Mail MTA instance will react differently depending on the type of connection it uses.
Each instance is named and registered as a Windows NT service on the Microsoft Exchange Server computer on which it was created and can be started or stopped independently of any other service.
Each instance has a primary connection type, although all instances can service LAN-Connected Post Offices. Depending on the number of Post Offices and what their connection type is, it might be more efficient to group the same connection types in the same instance. If the connection types are diverse, multiple instances should be created.
For example, if your network contains 10 LAN-connected MS MAIL 3.X Post OfficePost Offices and five Asynchronous-connected MS MAIL 3.X Post OfficePost Offices, it would be more efficient to create an instance on the Microsoft Mail Connector MTA for servicing only the LAN-connected Post Offices and another instance for connecting to and servicing the Asynchronous Post Offices.
If there are only two Asynchronous-connected MS MAIL 3.X Post OfficePost Offices and 10 LAN-connected MS MAIL 3.X Post OfficePost Offices, only one instance needs to be created on the Microsoft Mail Connector MTA for the Asynchronous connected Post Offices. Since all instances can service LAN connected Post Offices. The LAN connected Post Offices can then be added to the same instance.
If your organization contains a large number of MS MAIL 3.X Post OfficePost Offices, you might need multiple Microsoft Mail Connector MTAs for message connectivity between MS MAIL 3.X and Microsoft Exchange recipients. Since the same MS MAIL E-Mail address is used by every Microsoft Exchange Server in the site. MS MAIL essentially views each of the Microsoft Exchange sites as one large MS MAIL Post Office. Therefore, it is recommended for routing purposes, that one Microsoft Mail Connector MTA should be used for every Microsoft Exchange Server Site, which subsequently means multiple instances.
If you are going to use Multiple Microsoft Mail Connector MTAs, make sure each Microsoft Exchange Server has its own Microsoft Mail Connector MTA. Also, use duplicate address entries in two or more Microsoft Mail Connectors to route messages based on cost. This is useful for redundancy and load balancing traffic across connections and between servers.
Multiple MS MAIL 3.X Sites and individual MS MAIL 3.X Post OfficePost Offices can be coupled into a single messaging system using Microft Exchange Server as a Backbone to the existing MS MAIL 3.X messaging system. To make this connection, message transfer should first be set up between each of the Microsoft Exchange Server sites and a MS MAIL 3.X Post OfficePost Offices. Make sure that each of the MS MAIL 3.X Post OfficePost Offices correctly routes the messages to their destination through the Microsoft Mail Connector. When connected through a Microsoft Exchange Server, this will allow each of the MS MAIL 3.X Post OfficePost Offices to see the other MS MAIL 3.X Post OfficePost Offices as connected indirectly through one or more other Post Offices. If Directory Synchronization has been setup between any of the sites and the MS MAIL 3.X Post OfficePost Offices, all of the new information added to the Microsoft Exchange Server while setting up the message transfer between the sites and the MS MAIL 3.X Post OfficePost Offices, will be replicated to each of the connected Post Offices and the information shared by all (see fig. 6.5).
Basic site to site backbone configuration.
Using Existing MS Mail (PC) Gateways
Microsoft Exchange Server supports a wide variety of MS MAIL(PC) Gateways, which grant messaging services to other messaging systems. Supported MS MAIL(PC) Gateways include the following:
All of these Gateway programs come enclosed with Microsoft Mail Server 3.X on an options diskette included with the software. Each of the Gateway programs will require a short installation and configuration process. They are menu driven and easy to follow.
There are two ways Microsoft Exchange Clients can pass information through an existing MS MAIL 3.X mail system gateways. First, a typical gateway scenario in an existing MS MAIL 3.X environment would find the MS MAIL 3.X Gateway software running on a dedicated computer. A MS MAIL 3.X Post Office will need to selected as the Gateway Post Office. All messages destined for the foreign mail system will pass through this gateway Post Office, and vice versa. In order for Microsoft Exchange clients to access the actual Gateway and pass messages to the foriegn mail system, the Microsoft Exchange Connector Post Office needs to have the MS MAIL 3.X Gateway Access Component installed on it (see fig. 6.6). Secondly, if a Microsoft Exchange Server is selected as the Gateway Post Office, the MS MAIL 3.X Post Offices will then be required to hold a Gateway Access component. Either way will integrate a Microsoft Exchange Server into an existing MS MAIL 3.X Gateway scenario (see fig. 6.7).
Basic MS Mail 3.x Gateway Layout.
A typical gateway scenario.
Using Exchange Connectors as Gateways
If you decide on using Microsoft Exchange for your Gateway needs, Microsoft Exchange X.400 Connector or Internet Mail Connector or both will need to be installed on the Microsoft Exchange Server. The MS MAIL 3.X Post OfficePost Offices given access to the foreign mail service need to be connected to the Exchange Server via the Microsoft Mail Connector and must have a gateway access component installed on it. One benefit to using Microsoft Exchange as a Gateway is the ability to alleviate the need for a dedicated computer running the Gateway (see fig. 6.8).
When a mail message is sent from an MS MAIL 3.X Post OfficePost Office destined for the foreign mail service, the message is sent to the Microsoft Mail Connector, which passes it to either the Microsoft Exchange X.400 Connector and/or the Internet Mail Connector. The selected connector will then pass the message to the foreign mail service. For a message traveling from a foreign mail system, reverse the procedure.
The following figure illustrates another method using Exchange as a gateway.
Using Microsoft Exchange as a gateway.
Directory Replication and Synchronization
Directory Replication is the automatic process of replicating the Directory information between Microsoft Exchange Servers within a site. The information that is replicated includes all the information available about an organization's resources and users including mailboxes, public folders, distribution lists, servers, and more. Other components use the directory to map addresses and route messages. Replication can also be configured to automatically replicate all or only the desired amount of the directory information between multiple Microsoft Exchange sites.
Directory Synchronization is the process of keeping a Microsoft Exchange Server directory synchronized with directories from MS Mail (PC) and MS Mail (AppleTalk) systems. This is accomplished by the MS MAIL 3.X DISPATCH program included with the MS MAIL 3.X Server. Like Directory Replication between Microsoft Exchange Server sites, only the desired information will be transferred.
In order for a Microsoft Exchange Server to accomplish Directory Synchronization with a MS MAIL 3.X mail system, the Microsoft Exchange Server must be running the MS MAIL 3.X Directory Synchronization Agent. The Directory Synchronization Agent on a Microsoft Exchange Server plays one of two roles depending on the mail system environment, DIRSYNC Server or DIRSYNC Requester (see fig. 6.9). On an existing MS MAIL 3.X system, The Microsoft Exchange server can be configured as either a DIRSYNC Server or Requester (see fig. 6.10). However, the Microsoft Exchange Server cannot be configured as both a Server and a Requestor simultaneously. On a MS MAIL 3.X mail system, there can only be one DIRSYNC Server. All of the rest of the MS MAIL 3.X Post Offices can be configured as DIRSYNC Requestors.
If the Microsoft Exchange Server is configured as the DIRSYNC Server, it can synchronize all other MS MAIL 3.X Post Offices setup as DIRSYNC Requestors.
Once again, integration into an existing MS MAIL 3.X system is entirely conceivable and not difficult.
Using Microsoft Exchange as a DIRSYNCH server on an existing MS Mail system.
Using Microsoft Exchange as a DIRSYNCH Requestor on an existing MS Mail system.
This chapter has addressed the topic planning your Microsoft Mail Connector. For more information, refer to the following:
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