Migration Wizard searches the target Active Directory for user objects that match the mailboxes selected for migration. For each security identifier (SID) not found in Active Directory, Migration Wizard creates a disabled user object that corresponds to the account that you are migrating. Most matches are based on Microsoft Windows-based SIDs. In addition, Exchange Server 5.5 uses the SID to associate mailboxes with Windows user accounts.

If Migration Wizard finds a user object in Active Directory that matches the mailbox to be migrated, Migration Wizard:

• Connects to the source directory.
  
• Copies attributes from the source user object.
  
• Merges directory information from the source user object with the user object in the target Active Directory forest.
  
• Creates a mailbox on the target Exchange Server 2003 server.
  
• Connects to the source Exchange Server 5.5 server.
  
• Copies mailbox content from the source mailbox to the new mailbox on the target Exchange Server 2003 server.
  

If you migrate mailboxes to a new Active Directory forest but you keep the user objects in the current domain or forest, Migration Wizard will not find the appropriate SIDs in the target Active Directory. In this case, Migration Wizard:

• Creates a mailbox on the target Exchange Server 2003 server.
  
• Connects to the source Exchange Server 2003 server.
  
• Copies mailbox content from the existing mailbox to the new mailbox on the target Exchange Server 2003 server.
  
• Gives the source user object rights to access the target Exchange Server 2003 mailbox.
  

  Important:
  A trust relationship must exist between the source and target domains to allow the source user object to access its new Exchange Server 2003 mailbox. For more information about creating a trust relationship between separate domains, see the Windows 2000 Server or Windows Server 2003 Help.

  Note:

  The Windows Account Creation and Association page in Migration Wizard lists the mail accounts that you selected for migration. If an existing user object is located in Active Directory, the existing user object's distinguished name is shown in the Existing Windows Account column. If a disabled user object is created for the mailbox account, the disabled user object's distinguished name is shown in the New Windows Account column.

After searching for user objects, Migration Wizard searches Active Directory for contacts that match the mailboxes that are selected for migration. When a match is found, Migration Wizard:

• Reads directory information from the contact.
  
• Merges the information from the contact's attributes with the attributes for the new user object.
  
• Deletes the contact object.
  

The directory information from the contact object is merged with the user object's attributes based on the following rules:

• The target Active Directory is the most recent directory service.
  
• An attribute will not be overwritten if the target value already exists.
  
• Source multivalued attributes are preserved.
  
• An attribute will not migrate if it is not part of the target schema.
  

If Migration Wizard does not find any contacts, it considers the search process to be complete (no new objects are created).

Before you run Migration Wizard, it is recommended that you reduce the amount of Exchange Server 5.5 directory information and mail data as much as possible to ease the migration process. You can reduce the amount of data both before migration begins and during the migration process. Two ways to reduce data before you begin the migration are:

• Delete outdated files from your Exchange mail system.
  
• Instruct users to delete old mail and calendar data.
  

During the migration process, you can use Migration Wizard to reduce the amount of data that you migrate. On the Account Migration page, ensure that only the user accounts that you want to migrate are selected. On the Migration Information page, use the following options to specify what data should or should not be migrated:

• To migrate messages that are dated within a specific time period, select Migrate Mail messages within a date range. Then specify a date range by typing a starting date in the Date Range box and an ending date in the To box.
  
• To avoid migrating mail messages with specific subjects, such as a list of words or letters, select Do not migrate mail messages with specific subjects. In Subject List File, click Browse to locate the file that contains the subjects that you want to filter.
  

  Note:
  The files in Subject List File must be saved in Unicode file format.

To install the Exchange Server 2003 version of Active Directory Connector (ADC), you must have at least one server in each Exchange site running Exchange Server 5.5 SP3. The account that you use to install ADC must be a member of the Enterprise Administrator, Schema Administrator, and Domain Administrator groups. The account must also be a Local Machine Administrator on the local machine.

Exchange Server 5.5 and Exchange Server 2003 Coexistence

Active Directory Connector Requirements When Migrating Exchange 5.5

Inter-Organizational Connection Agreements and Two-Way Replication

Although inter-organizational connection agreements can only be configured to replicate in one direction, you can achieve coexistence by configuring two one-way inter-organizational connection agreements between the Exchange Server 5.5 server and Active Directory. Setting up two one-way ADC inter-organizational connection agreements that point in opposite directions enables the inter-organizational ADC to replicate the Exchange Server 5.5 directory information to Active Directory and to stamp replicated objects with the X500 address of the Exchange Server 5.5 mailbox. If you use the inter-organizational Active Directory Connector for directory synchronization during coexistence, do so only during the migration process.

Note:
When you establish two one-way inter-organizational connection agreements, ensure that the target container of one connection agreement is not the source container of the second connection agreement.

X500 Addresses

Identifying Resource Mailboxes

A primary mailbox is the mailbox where a user receives mail. A non-primary (or resource) mailbox is a mailbox created for resources such as conference rooms or group mailboxes. Resource mailboxes are owned by users who also own a primary mailbox. In Exchange Server 2003, a mailbox is an attribute of an object in Active Directory, not an object itself. Therefore, each user object in Active Directory can only be matched to one mailbox, which is the user's primary mailbox.

Resource mailboxes become separate objects in Active Directory during the migration process. For this reason, resource mailboxes must be identified before running Migration Wizard so that Migration Wizard handles them differently than primary mailboxes. Migration Wizard identifies resource mailboxes that are to be migrated by searching for the value NTDSNoMatch in the custom attributes for each resource mailbox. For this reason, if a user has a primary mailbox and one or more resource mailboxes, all mailboxes but the primary mailbox must be stamped with the value NTDSNoMatch.

Important:
Migration Wizard will only migrate multiple mailboxes that are associated with the same user if all but one of the mailboxes are stamped with the value NTDSNoMatch.

In addition to the initial migration tasks that you must perform, mailbox users must perform the following tasks before you run Migration Wizard:

• Remote access users must synchronize their offline folder store (.ost) files with the Exchange Server 5.5 server so that any messages in their Outbox will be sent.
  
• Exchange client and Schedule+ users must synchronize their schedule (.scd) file with the Exchange Server 5.5 server.
  
• Users must decrypt encrypted messages.