Zimbra to On-Premises Exchange Migration Guide


This is the complete onboarding task flow for migrating mailboxes from Zimbra (version 6 and later) to On-Premises Microsoft Exchange versions 2013, 2016, or 2019. 

MigrationWiz no longer supports TLS 1.0.  TLS 1.2 is now required. Verify TLS version and update, if necessary, before starting the migration.

This migration guide contains the necessary steps to perform the actual migration, but there are many steps to preparing for migration. If this is your first time performing a migration, we have created a Migration Planning & Strategy Guide to walk you through planning, set-up, and general migration best practices.

To discover what items are moved with MigrationWiz in this scenario, and which items will not be moved, see Moved Items. Note that these items will vary by source and destination, so check the proper environment listings carefully.

MigrationWiz is a migration tool, not a syncing tool. If changes are made at the source after migration, they will not sync to the destination, nor will changes made at the destination sync to the source. We do not have “live” monitoring of changes (as with a sync agent) and we cannot handle scenarios such as conflict resolution without user interaction.

MigrationWiz supports the capability to share migration projects across a Workgroup. When the Project Sharing feature is turned on, all Agents besides those who are Inactive can view all migrations projects. For more information, visit Project Sharing in MigrationWiz. 

We are not able to support migrations with two-factor or multifactor authentication. 


Prepare the Source Environment

 Note: Users will need to enter usernames on the Zimbra side, even when using an admin account.

  1. Export the list of users to a CSV file. This will be used when adding users to your MigrationWiz mailbox project. KB005011
  2. Inform users to split up folders that have a very large number of items.
    • Zimbra will exhibit poor migration performance for folders with a large number of items.
    • Calendar folders can be slower to migrate when the data is complex. For example, recurring calendar meetings result in a much higher number of calendar events.
  3. Ensure that you have admin credentials available for use during migration.
    • Use existing credentials.
    • Create a new admin account for migration. This will create an additional admin account with the password of 'test123':
      zmprov ca testadmin@domain.com test123 zimbraIsAdminAccount TRUE
    • Transform a normal existing user account into an admin account (in this example future-admin will become an admin):
      zmprov ma future-admin@domain.com zimbraIsAdminAccount TRUE
  4. Test mailbox access. KB004332
  5. Make sure the necessary ports to connect to the Zimbra server are open. Access to SOAP web services is needed for migration. This is via both regular and admin user mode. Ports 80, 443, and 7071 are the common ports. KB004139


Prepare the Destination Environment

  1. Set up user accounts.
  2. Create an admin account for migration that has full access permissions to all mailboxes. KB004725
    • Get-Mailbox -ResultSize Unlimited | Add-MailboxPermission -AccessRights FullAccess -Automapping $false -User MigrationWiz Notes:
      • In the PowerShell script above, change the -User account to match the name of the admin account that was set up for migration.
      • Any user account that is a part of the domain administrator, schema administrator, or enterprise administrator groups will not have any administrative rights to mailboxes, no matter how many permissions are granted. A security default of Exchange Server is to explicitly deny any user that is a member of these groups. This is why we recommend creating a new user account specific for migration.
    • Set up a remote PowerShell session with Exchange 2010+. KB005111
    • To manually grant administrative access for migration, execute the following PowerShell command in the Exchange Powershell Console:
  3. Disable throttling against the admin account. Refer to Option 1 in KB004945.
  4. Verify mailbox accessibility, using EWS.​ KB004304
  5. If you want to be able to migrate messages with attachments larger than 10MB, the following limits need to be increased:
    • Increase message size limits. KB004613
    • Increase maximum accepted content length. KB004609
    • Increase maximum receive message size. KB004532
    • Increase maximum accepted re​​​​quest length. This is only valid if your Destination server is running Exchange 2007. KB004610


MSPComplete Steps

  1. Create the customer. KB005421
  2. Create the Source and Destination endpoints. KB005427
    • For the Source endpoint:
      • Click Endpoints > Add Endpoint > Enter endpoint name > For endpoint type, select Zimbra 6.5+.
      • Enter Zimbra server URL KB004331
      • Click the Provide Credentials radio button, and enter the admin account credentials. These are either your existing admin credentials or the credentials for the account that was created under the "Prepare the Source Environment" section of this guide.
    • For the Destination endpoint:
      • Click Endpoints > Add Endpoint > Enter endpoint name > For endpoint type, select Exchange Server 2003+.
      • Enter the OWA URL KB004392
      • Click the Provide Credentials radio button, and enter the admin account credentials for the account that was set up under the "Prepare the Destination Environment" section of this guide.
  3. Purchase User Migration Bundle licenses. User Migration Bundle licenses allow multiple types of migrations to be performed with a single license. They also allow DeploymentPro to be used to configure Outlook email profiles. Refer to these articles for more information:



MigrationWiz Steps

  1. Create a Mailbox Migration project. Read the How do I create a new migration project? article for more information.
  2. Add the accounts (also referred to as "items") that will be migrated to the project. KB004842
  3. Set the Project Advanced Options. KB004834
    The following options are most valuable for this migration scenario:
    • Set Maximum concurrent migrations. We recommend setting this to a very low value, such as 5, to ensure that server utilization does not go above 80%. If the Source Zimbra server is running low on resources, it can result in email being migrated as blank. If the Source server has enough server resources, set this parameter based on the bandwidth guideline of three (3) mailboxes per 1Mbps of bandwidth. Therefore, for example, if there is a 10Mbps connection, we recommend setting the maximum concurrent migrations parameter to be 30. If the Source server has very few available server resources (e.g., it is running low on memory or it has very high CPU utilization), we recommend setting this value to a lower number to avoid overwhelming the Source server with requests.
    • Under Support/Support options, add: ZimbraCalendarExpandInstances=1 KB005122
  4. Run Verify Credentials. KB004511
  5. Notify users that a migration is occurring. Send email to all users, telling them the time and date of the migration.
  6. Pre-Stage pass: Select the users > Click the Start button from the top, and select Pre-Stage Migration > Under the Migration Scheduling section, from the drop-down list, select 90 days ago > Click Start Migration. KB004938
  7. MX Record Cutover. Change over MX records on the DNS provider's portal. Also, include the AutoDiscover (CName) setting.
    Note: If migrating in batches and mail coexistence is required, you will not be cutting over the MX records until your final batch of users has been migrated, and you must perform this extra step:
    • Set up Zimbra mail forwarding. KB004256
  8. Send email to end users to let them know what to expect for their Outlook profile reconfiguration. If using DeploymentPro, refer to KB005799 for some sample text and screen shots that can be included in this email.
  9. Full (Delta) pass: Select the users > Click the Start button from the top, select Full Migration > Click Start Migration. KB004938
  10. Run Retry Errors. KB004658
  11. Look through the user list and click any red "failed migration" errors. Review the information and act accordingly.
  12. If problems persist, contact Support. KB004529
  13. If not using DeploymentPro, users must create new Outlook profiles, and set up their signatures again, and reattach any PST files that were attached to their previous profile.
  14. Click the pie chart icon in the MigrationWiz dashboard to receive an email containing all the project migration statistics. KB004626


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