Migrating to Microsoft Exchange Server

Archiving External Messages
In our new, somewhat elaborate, SMTP environment, the archiving objective becomes simpler. We already proved that with built-in Exchange features, we can distinguish and, more important, reroute SMTP messages based on domain names. Also, we know that message archiving is an optional IMC function. We concluded that an additional IMC, dedicated to processing external messages, was our only requirement.

Figure 2 shows that we added an Exchange server, Extmail, and outlines configuration settings for the Our Firm site: We have two Exchange servers. Intmail is home server to all Exchange mailboxes and Custom Recipients. The Intmail IMC routes gw.ourfirm.com messages to the GroupWise SMTP gateway and all other mail to Extmail. The message archival feature of Intmail's IMC is disabled. We added Extmail to the site to send and receive Internet mail. Extmail uses DNS to deliver messages to appropriate Internet mail hosts. We configured Extmail to archive SMTP messages.

Again, let's trace the route of messages and their replies, to examine the design. Assume we've already contacted our client's ISP to add an A record (DNS terminology for the record that contains the IP address and fully qualified domain name of a computer and that is used for name resolution) for Extmail and to modify our MX record directing mail to Extmail.

Mail from an Exchange user, user@ourfirm.com, addressed to president@whitehouse.gov leaves the Exchange site via Extmail's IMC, which is configured with a global wildcard address space (*). Extmail uses DNS to find the appropriate mail host for whitehouse.gov and transfers the message. Extmail receives the reply, addressed to user@ourfirm.com, and subjects the message to the criteria of imcroute.cfg (the IMC Sample Extension DLL configuration file). If Extmail finds a match, the message is rerouted to the local host and IMC handles it. After archiving the message, Extmail's IMC delivers the message to the recipient's Exchange mailbox. No alternate recipient is specified, so the users receive the message in their inbox.

A GroupWise message to Exchange is different from our previous model. The message, from davej@ourfirm.com to user@ourfirm.com, reaches the GroupWise SMTP gateway, which directs the message to Intmail. If the message matches the criteria in imcroute.cfg, the message path is localhost, Intmail's IMC, and the message will be delivered to Exchange (this path includes no message archival). The reply is addressed to davej@ourfirm.com, which is a valid Exchange mailbox, configured to reroute mail to davej@gw.ourfirm.com. Intmail's IMC, configured with address space and message delivery options, transfers this reply to gw.ourfirm.com. The GroupWise SMTP gateway performs a directory lookup for davej and passes the message to the user's mailbox.

Again, GroupWise messaging with the Internet is the best illustration of our proposal. A message from davej@ourfirm.com to president@whitehouse.gov travels through the GroupWise SMTP gateway to Intmail, doesn't match domain criteria in imcroute.cfg, enters Intmail's IMC (isn't archived), is forwarded to Extmail, doesn't match domain criteria in imcroute.cfg, enters Extmail's IMC, and is archived and forwarded to the appropriate mail host for whitehouse.gov. The reply to this message (to davej@ourfirm.com) follows an equally ambitious route. From the whitehouse.gov SMTP host to Extmail (found via DNS lookup), the message matches the criteria of imcroute.cfg, is rerouted to localhost, is archived, and is delivered to Exchange by the IMC. Based on the alternate recipient configuration (to davej@gw.ourfirm.com) of my Exchange mailbox, the message then travels to Intmail's IMC, to the GroupWise SMTP gateway, and to my GroupWise mailbox.

Complex but Effective
Although our messaging project was not simple, Exchange Server answered our toughest challenges. We used NT's NetWare migration tool to create accounts and Exchange's Directory Import feature and Microsoft Access to create mailboxes and Custom Recipients. Within minutes after import file setup and sample runs, we had a complete directory of all user mailboxes, hidden Custom Recipients, and corresponding Windows NT accounts. Later, still using Directory Import and Access, we effortlessly modified each mailbox to include items such as department and distribution list membership.

Although industry regulations for message archival are not commonplace, our solution can be practical in countless other scenarios. For example, although our solution discusses migration from Novell's GroupWise, you can apply this solution in migrations to Exchange from any mail platform that supports SMTP. Also, to comply with the Federal Records Act, many government agencies retain copies of electronic communications involving matters of public record. These organizations can use parts of our solution to archive internal and external mail. In today's world of business partner connectivity and increased online vendor and customer correspondence, Microsoft Exchange has many options to offer. Its flexibility, however, underscores the value of critical thinking before implementation.