This section describes considerations to be made before migrating from a Microsoft Exchange server to Communications Suite.
The Exchange server contains valuable user information, and an efficient migration will extract and use this information to provision the user accounts on the new Communications Suite server. In addition to users' old mail messages, the old server contains user calendars, tasks, and personal address books and contacts. The old server also contains user names, primary Internet addresses, Internet aliases, phone numbers, postal addresses, and even descriptive information such as users' departments, titles, and so forth, and also all of the enterprise's public distribution lists.
While a detailed account of server data migration is beyond the scope of this document, the old server is a valuable data resource that can be mined to drive user provisioning on the Communications Suite servers, as well as changes in mail routing. Sun Professional Services can help you to understand and accommodate server data migration in your deployment plan, and other third-party companies offer both technology and consulting expertise to facilitate the migration of your server data.
Not all users will migrate from the old server to the new server at the same time. User accounts on the new server are created and provisioned prior to users' actual migrations. As such, user mailboxes with the same address will reside on both the old and new servers simultaneously during your transition period. Some temporary mail-forwarding rules must therefore be defined to make sure that your users' mail is correctly routed during the transition period.
Even if the organization is implementing new Internet addresses, the old addresses must be maintained on the old server because replies to older messages will be deliverable only if the users' old primary Internet addresses continue to deliver to the correct server. Since all Internet mail for a given domain must go to a single server, specified in an associated MX record, your organization must decide when it will update its MX record to point to the new Sun Java System server.
If the MX record is switched to the Communications Suite server at the beginning of the transition period, you must configure the Communications Suite server so that any mail it cannot deliver to a local mailbox will be sent to the corresponding mailbox on the old server. Moreover, as new users are provisioned on Communications Suite, forwarding rules must be defined on the new server so that any mail that would normally be delivered to the new mailboxes will instead be forwarded to the corresponding user mailboxes on the old server. As each user migrates to the new server, delete the first forwarding rule on the new server, and define a new rule on the old server to forward all of the user's mail to the corresponding Communications Suite mailbox.
On the other hand, if the MX record will point to the old server until the end of the transition phase, configure the old server to send mail it cannot deliver locally to the corresponding user mailboxes on the Communications Suite server. As users migrate to the new server you must then define new rules on the old server to forward mail sent by other users on the old server to the users' new accounts on the Communications Suite server.
Larger organizations are likely to require weeks or months to complete a phased migration, and during transition there will be some users on each of the two systems. Many organizations prefer that all users maintain access to an accurate enterprise directory (white pages, global address book), but accuracy will require regular synchronizations of the two servers' directories as employees are hired, transferred, terminated and so forth. The deployment plan should therefore specify some mechanism for regularly synchronizing the two directories throughout your transition period.
Sun Professional Services can assist in addressing this issue. There are also several products available to perform directory synchronization.
Most network systems are designed to prevent people from discovering user passwords, and this is particularly true of Microsoft Exchange. These security safeguards make it impossible to automatically retain users' existing passwords as they migrate from the old server to the new.
Meanwhile, many organizations prefer to standardize the form of their Internet addresses, or to combine domains during their migration to Communications Suite. An organization must therefore decide, in advance, how account names and Internet addresses will be derived, and how users' new passwords will be assigned.
The network administrator must also devise a method for communicating these user credentials to both the users and the corporate help desk. One common approach is simply to prepare an email merge, just prior to a group's migration, so that each member of the migrating group receives his or her credentials independently, and just in time for the group's first logins to the new server.