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Migration Manager for Exchange 8.15 - User Guide

Pre-Migration Activities Migration Process Calendar Synchronization Mailbox Migration Public Folder Synchronization Free/Busy Synchronization Tracking the Migration Progress Creating Batches of Synchronization Jobs Outlook Profile Update Fine-Tuning the Agents Using Agent Hosts for Migration Agents Configuring Migration Using PowerShell Appendix A. Measurement of Migration Agent for Exchange Performance Appendix B. Migrating Large Public Folders to Exchange 2013 (or Higher) and Office 365 Appendix C. Migration of Recoverable Items Subfolders (Optional)

Adding a Native Move Collection

To create a new mailbox collection for an existing native move job, right-click the job in the management tree and click Add Collection.

This will start the Add Mailbox Collection Wizard, which will help you to set up and configure a new collection for the native move job. Each step of the wizard is described below.

Step 1. General Options

Specify the following general options:

  • The name of the native move collection
  • Optionally, a text description
  • Whether the collection will be enabled immediately after creation
  • The mailbox database that the mailboxes in the collection will arrive in
  • The instance of the Migration Agent for Exchange that will process this collection

Step 2. Target Options

Specify the mailbox database to move mailboxes to and the domain part to use in their primary SMTP addresses.

Step 3. Configure Mailbox Switching

The final step in mailbox migration is to switch to the target mailbox, making it the primary mailbox for the user. You can select to perform this step automatically and specify a schedule for it.

However, you may want to defer this step in case there are problems and perform the switch manually when you have made sure the mailboxes are ready.


  • If migration source is an Exchange 2003 organization, mailboxes will always be switched automatically regardless of selected option.
  • If you select to switch mailboxes manually, you need to configure SMTP connector between the source and target organization so that primary SMTP addresses will be routable from the target domain.

Step 4. Workflow

When processing the collection Migration Manager will attempt to follow the schedule you specify on this page. By default, the option to Start as soon as possible is selected. Change this if you want to specify a date when the collection processing should be started.

Do one of the following:

  • Select Start as soon as possible to make Migration Manager start moving the mailboxes in this collection immediately.
  • Select Do not start before to make Migration Manager start processing the collection no sooner than the specified date, but this might not be the first collection in the queue.

An additional workflow-related consideration is how to treat mailboxes with corrupted items (messages) in them.

If you think it is acceptable that mailboxes in the collection may have corrupted messages, select the Skip the corrupted messages option and specify the maximum number of corrupted messages that a mailbox can have and still be moved.

You can supply a number in the range from 1 to 2147483647 (the upper bound effectively means move mailboxes no matter how corrupted their contents are).

Step 5. Collection Items

The collection can be populated with user accounts. To change the user account list, use the buttons next to it.

NOTE: Migration Manager for Exchange does not process groups nested in organizational units (OUs).

Manually Switching Mailboxes

  1. Select the node of the native move collection you need.
  2. In the right pane, go to the Statistics tab.
  3. Select the mailboxes you need in the table at the bottom
  4. Click the Switch action.

Caution: Mailbox switch for mailboxes migrated using native move cannot be undone.

Exchange 2010 Considerations

If an Exchange 2010 organization is involved in the mailbox migration process, consider that in Exchange 2010 all mailbox communications flow via Client Access Servers (CAS) instead of Mailbox Servers as in previous versions of Exchange. Therefore Migration Manager for Exchange agents use CAS for mailbox and calendar processing.

In addition, if an Exchange 2010 organization acts as a migration destination, consider the following:

  • After a mailbox move operation is performed or a new Exchange 2010 mailbox is created during the migration process, the mailbox does not immediately become available for login. The Mail Target Agent will record login errors until the mailbox is ready (this can take up to 20 minutes). In these situations, login errors can be safely ignored.
  • If a mailbox move request completes with an error, delete this request before the agent creates a new one.

Exchange 2013/2016/2019 Considerations

When migrating mailboxes to Exchange Server 2013/2016/2019, consider the following:

  • Migration Agent for Exchange cannot process a message that is larger than 40MB. This limit is set in Migration Manager for Exchange configuration project to ensure migration stability. If you have strong reasons to change that value, see the SizeLimitInMbPerBatchUploadToO365 and SizeLimitInMbPerBatchUploadToExchange parameters in Configuring Migration Using PowerShell

  • If you want to change an agent instance for a collection that is being processed, you should stop the agent, wait until the current session is finished and then specify the agent instance you need.
  • If a mailbox is added to more than one collection via groups or organizational units, the Migration Agent for Exchange processes this mailbox only for the collection that is the first in the synchronization order.
  • One instance of Migration Agent for Exchange cannot process collections from on-premise Exchange migration and Microsoft Office 365 migration projects at the same time.
  • If a mailbox move request completes with an error, delete this request before the agent creates a new one.

Public Folder Synchronization

Public folder synchronization should be started before mailbox migration and before calendar and free/busy synchronization. This order of migration allows the users to keep using their public folders during the entire migration period, regardless of which mailbox (source or target) is currently used by the user.

NOTE:If you plan to migrate public folders to Exchange 2013/2016/2019 organization or Microsoft Office 365, review information provided in the Appendix B. Migrating Large Public Folders to Exchange 2013 (or Higher) and Office 365 section.

If you plan to synchronize public folders with Microsoft Office 365, also see the Migrating to Microsoft Office 365 document.

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