XFOR: How to Backbone MSMail 3.x over Exchange

- Microsoft Exchange Server, version 4.0

SUMMARY

This article describes how to backbone Microsoft Mail 3.x over a Microsoft Exchange Server.

MORE INFORMATION

NOTE: At this point you can only send mail. If you don't have directory replication setup between the two sites you won't be able to reply to any messages that are sent by MS Mail users from outside of your site.

To backbone Microsoft Mail 3.x over a Microsoft Exchange Server there are a few items that must be configured correctly before it will work.

The interesting thing about backboning over Microsoft Exchange is the ability to use all the connectors that come with Microsoft Exchange. We can use the Internet Mail Connector, X.400 Connector, and the Site Connector. The trick to doing this is assigning the correct address space to each connector that you use and having custom recipients for the MSMail users. Microsoft Exchange needs the custom recipients to resolve the address to a user.

The best way to explain this is by example. In this example we will have two Microsoft Exchange Sites connected in various ways and two Microsoft Mail post offices. We will call the Microsoft Exchange sites A and B. The post offices will be on the mail network of MICROSOFT and be called PO1 and PO2.

To begin we will connect the Microsoft Exchange sites. Site A will connect to site B via an X.400 connector. After connecting the Microsoft Exchange sites, connect in the Microsoft Mail post offices. In this example, we will connect PO1 to Site A and PO2 to Site B. What this includes is setting up the Microsoft Mail Connector on Site A and Site B.

Now what we have looks like this:

           PO1 -> Site A -> Site B -> PO2

Microsoft Exchange uses custom recipients to resolve Microsoft Mail addresses. These custom recipients will have to be created at Site A and Site B. Site B will have a custom recipient for every user on the Microsoft Mail post office PO2. Likewise, Site A will have a custom recipient for every user on the Microsoft Mail post office PO1. As an administrator, the recommended way to get the custom recipients into Microsoft Exchange is to DirSync them in. The other way is to manually create a custom recipient for each user. This can also be done via an import file and using the Microsoft Exchange Administrator program.

ESTABLISH ROUTE FROM PO1 to PO2

At Site A, run the Microsoft Exchange Administrator program and go to the object for the X.400 connector to Site B. On this connector, add the address space for Microsoft Mail. At this site, use MICROSOFT for the network and PO2 for the post office in the address space. Leave the mailbox entry empty so every piece of mail addressed to anyone on PO2 will go through. At this point we defined the route to PO2.

ESTABLISH ROUTE FROM PO2 to PO1

At Site B, run the Microsoft Exchange Administrator program and go to the object for the X.400 connector to Site A. On this connector, add the address space for Microsoft Mail. At this site, use MICROSOFT for the network and PO1 for the post office in the address space. Leave the mailbox entry empty so every piece of mail addressed to anyone on PO1 will go through. At this point we defined the route to PO1.

MOVING MAIL

Now that the routes are defined in Microsoft Exchange we need to define the routes in Microsoft Mail. On post office PO1 we need to define post office PO2 as indirect via the shadow post office in Site A. This will send all mail addressed to PO2 to the shadow post office on the Microsoft Exchange server. When the mail reaches the shadow post office, the Microsoft Mail Interchange service will retrieve the mail and hand it off to the Microsoft Exchange Message Transfer Agent (MTA) for routing. We need to do the same on post office PO2. At post office PO2, define post office PO1 as indirect via the shadow post office on the Microsoft Exchange Site B. This will send all mail addressed to PO1 to the shadow post office on the Microsoft Exchange server. This completes the Microsoft Mail configuration.

Now that all the routes are in place we can move mail. To address mail from PO1 to someone on PO2 we must have some pieces in place. We need to have an MTA that moves mail from the Microsoft Mail post office to the Shadow post office on the Microsoft Exchange Server. This article assumes that these are in place. Now that these are in place we can "one-off" address to a user on another post office.

MORE INFORMATION

The above setup allows the users on the Microsoft Mail post offices to "one- off" address to another user. To avoid this we can use directory synchronization. Directory synchronization will allow user lists on both post offices to be updated. This will allow the users to pick another user from the global address list or the network post office address list.

Another item to consider is implementing a Directory Replication Connector between the Microsoft Exchange Sites. This will eliminate the need for assigning address spaces to the connectors. When directory replication is involved, the Microsoft Exchange MTA will be able to know more about the mail routing. Each Microsoft Exchange site will be able to resolve the address and choose the correct route for the mail message.