Zimbra to Microsoft 365 Migration Guide

This is the complete onboarding task flow for migrating mailboxes from Zimbra (version 6 and later) to Office 365. MigrationWiz no longer supports TLS 1.0.  TLS 1.2 is now required. Verify the TLS version and update, if necessary, before starting the migration.

App passwords are not supported for the Microsoft 365 endpoint. 

First migration?

We created a guide on scoping, planning, and managing the migration process for your use. If this is your first migration, we recommend you read this guide carefully.


MigrationWiz is a migration tool, not a syncing tool. If changes are made at the source after migration, they do not sync to the destination, nor do the changes made at the destination sync to the source. We do not have “live” monitoring of changes (as with a sync agent) and 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. 

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

Zimbra 6+

What items are and are not migrated?


  • Inbox
  • Folders
  • Email
  • Contacts
  • Calendars
  • Tasks

Not Migrated

  • Zimbra Tags

Prepare the Source Environment

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

Export Users

Export the list of users to a CSV file. This will be used when adding users to your MigrationWiz mailbox project later in the migration.

  1. Open Zimbra Admin.
  2. Select Account.
  3. In the Search box, type the domain name to be exported.
  4. On the Toolbar Zimbra Admin, select the Download button.
  5. Save the CSV file generated.

Split Large Folders

Direct 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.

Prepare Admin Credentials

Ensure that you have admin credentials available for use during migration. If electing to assign the admin role through the Zimbra administrator portal instead of the below commands, the user needs to be granted Global Administrator. Assigning just an Administrator will not work.


    • 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

Test mailbox access

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 modes. Ports 80, 443, and 7071 are the common ports. 

There are two modes to connect to a Zimbra server, Regular and Admin User mode.

  1. In regular user mode, we need access to SOAP web services, which are typically the following:
  • ​On port 80 if it is an HTTP connection.
  • On port 443 if an HTTPS connection.
  • In admin user mode, we also need access to SOAP web services, typically:
    • ​On ports 80 and 7071 when the Zimbra URL is HTTP.
    • On ports 443 and 7071 if the Zimbra URL is HTTPS.
  • You need to connect using both ports. Some operations will go over the admin port, while others will go over the regular port.

    Prepare the Destination Environment

    Create the admin account

    1. Create a user in Microsoft 365
    2. Connect to Exchange Online by using remote PowerShell
    3. Type the following command, and then press Enter:
      Get-Mailbox -ResultSize unlimited -Filter {(RecipientTypeDetails -eq 'UserMailbox') -and (Alias -ne 'Admin')} | Add-MailboxPermission -User AdministratorAccount@mydomain.com -AccessRights fullaccess -InheritanceType all

    After you perform these steps, the specified user will be able to access all user mailboxes in Microsoft 365. The user will be able to view the contents of the mailboxes from either Outlook or Outlook Web App.

    Set up accounts in Microsoft 365

    1. Set up accounts on Office 365 and assign licenses. These can be created in several ways:

    Modern Authentication Requirements

    The steps listed in the Obtain Client and Tenant ID Settings for Mailbox and Exchange Online Migrations section of the Authentication Methods Migrations KB apply to both the source and destination tenant when they are Exchange Online, in regards to Exchange Web Services (EWS) in mailbox, archive mailbox, and public folder projects. Use a Global Administrator for the configuration steps.

    Please review the documentation before preparing the destination.

    Prepare the tenant to send & receive large items

    We do not impose any limit on item/attachment sizes. However, large items/attachments can fail to migrate because of external factors.  There are two considerations:​

    1. What is the maximum attachment size allowed by the Destination system? 
    • Most email systems impose size limits. For example, if the Destination system has a 30MB limit, any item/attachment larger than 30MB will fail to migrate.
  • What is the connection timeout for the Source and Destination system? 
    • ​​For security reasons, most email systems close opened connections after a predetermined amount of time. For example, if the Destination system only has 512Kbps of network bandwidth and closes connections after 30 seconds, we may be unable to transfer large items/attachments before the connection is closed.

    MigrationWiz will automatically make multiple attempts to migrate large items. Upon completion of a migration, you may resubmit it in error retry mode to try to migrate failed items. This is always free of charge.:

    When migrating from or to Office 365 use the steps provided here to increase the Max Send and Max Recieve quotas, Change message size limits in Office 365.

    Purchase licenses

    We recommend purchasing the User Migration Bundle license for this migration scenario. 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. For questions on licensing, visit MigrationWiz Licenses

    To purchase licenses

    1. Sign in to your BitTitan account. 
    2. In the top navigation bar, click Purchase.
    3. Click the Select button and choose User Migration Bundle licenses.
    4. Enter the number of licenses you want to purchase. Click Buy Now.
    5. Enter a Billing address if applicable.
    6. Click Next.
    7. Review the Order Summary and enter a payment method.
    8. Click Place Your Order.

    Apply for licenses

    1. Select the correct workgroup on the top of the left navigation pane. This is the workgroup that the customer and migration project were created under. Your account must be part of the workgroup if the project was not created under your account.
    2. On the left navigation pane, click Customers.
    3. Click the customer that employs the user to whom you want to apply for a User Migration Bundle license.
    4. Click the Users tab at the top of the page.
    5. Check the box to the left of the email for the user(s) to whom you want to apply for a license.
    6. Click the Apply User Migration Bundle License button at the top of the page. It is recommended that users be added to the Customer page with the vanity domain. Then have the User Migration Bundle Licenses applied, before editing to show the .onmicrosoft domain, if the .onmicrosoft domain will be used for the migration.
    7. If at least one unassigned User Migration Bundle license is available for each selected user, click Confirm.

    MigrationWiz Steps

    Create a Mailbox Migration project

    1. Click the Go to My Projects button.
    2. Click the Create Project button.
    3. Click on the type of project that you wish to create. For this migration:
    • Mailbox: Mailbox projects are used to migrate the contents of the primary user mailbox from the previous environment to the new environment. Most mailbox migrations can migrate email, calendars, and contacts.

    For mailbox migrations, use administrative credentials to access mailboxes. In most migration scenarios, the admin account needs to have full access rights to the Source mailboxes. 

      1. Click Next Step.
      2. Enter a Project name and select a Customer.
      3. Click Next Step.


    Endpoints are now created through MigrationWiz, rather than through MSPComplete. The steps for this section outline how to create the endpoints in MigrationWiz.

    If you are selecting an existing endpoint, keep in mind that only ten endpoints will show in the drop-down. If you have more than ten, you may need to search. Endpoint search is case and character-specific. For example, Cust0mer will not show up if the search is customer. We recommend keeping a list of endpoints you have created, along with any unique spellings or capitalization you may have used.

    You may either use existing endpoints or create new ones. 

    Create a New Source Endpoint

    1. Click Endpoints.
    2. Click Add Endpoint.
    3. Select Zimbra 6.5+.
    4. Enter Zimbra server URL.

    5. 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.

    6. Click Add.
    7. Click Next Step.

    Create a New Destination Endpoint

    1. Click Endpoints.
    2. Click Add Endpoint.
    3. Enter endpoint name.
    4. Select endpoint type Office 365.
    5. Click Provide Credentials.
    6. Enter the admin account credentials. This should be for the global admin account. 
    7. Click Add.
    8. Complete the Application (client) ID and the Directory (tenant) ID fields, otherwise, you cannot save your project.

      Destintation Settings.png

    9. Click Next Step.


    When configuring the destination endpoint, do not forget to complete the client ID and the tenant ID fields for the Destination endpoint, otherwise, you cannot save your project migration.

    Once the information has been provided for both, the source and/or destination endpoint, and the customer selects Save and Go to Summary, MigrationWiz performs an endpoint validation check for the Microsoft 365 endpoint.

    This validation tests the administrator credentials entered into the project and the Modern Authentication setup only. If there is an issue, the screen redirects to the endpoint and provides an error message or flyout that can be selected for more information regarding the error.

    Common Errors when Configuring Your Endpoint

    For more information, review the AADSTS700016, AADSTS90002, and ADDSTS50126 issues on the Common Errors Using Modern Authentication page.

    Add Users

    Add the user accounts that will be migrated to the project. MigrationWiz allows you to bulk import mailboxes into the system. Note: The Username of the source mailbox needs to be for the user mailbox being migrated and not the Zimbra administrator account.

    Use the Bulk Add option and import from the CSV file, the one prepared under the Prepare the Source section of this guide. 

    To import one or more mailboxes, follow the next steps.

    1. Sign in to your MigrationWiz account.
    2. Select the Project for which you want to perform the bulk import.
    3. Click on Add.
    4. Click on Bulk Add.
    5. Follow the instructions on the page.

    Add Advanced Options

    Recommended Options

    Under Support/Support options:

    • Set the project to use impersonation at Destination. Checkmark the Use impersonation at Destination box. 
    • Set Maximum concurrent migrations. We recommend setting this to a meager 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 30. In case the Source server has limited available resources such as low memory or high CPU usage, we suggest setting a lower value to prevent overloading the server with requests.
    • Add: ZimbraCalendarExpandInstances=1

    Default Options

    The client and tenant ID fields for the destination in the Support tab of the project’s Advanced Options, are view-only fields. This means that you cannot edit or remove them from the support options page. To edit them,  you need to edit the project.


    You cannot update the default Advanced Options, in case you try to modify or add new ones the following message arises.
    Duplicate Support Option.png

    Run Verify Credentials

    1. ​Sign in to your MigrationWiz account.
    2. Open the Project containing items you wish to validate.
    3. Select the items you wish to validate.
    4. Click on the Start button in your dashboard.
    5. Select Verify Credentials from the drop-down list.

    Once complete, the results of the verification will be shown in the Status section.​ 

    Notify Users

    Notify users that a migration is occurring. Send an email to all users telling them the time and date of the migration.

    Run Migration

    Pre-Stage pass

    1. Select the users you wish to migrate.
    2. Click the Start button from the top.
    3. Select Pre-Stage Migration.
    4. Under the Migration Scheduling section, from the drop-down list, select 90 days ago.
    5. Click Start Migration.

    MX Record Cutover

    • Change over MX records on the DNS provider's portal.
    • Also, include the AutoDiscover (CName) setting.

    If you are migrating in batches and 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 two extra steps:

    Full pass

    1. Select the users.
    2. Click the Start button from the top.
    3. Select Full Migration.
    4. Click Start Migration.

    Run Retry Errors

    Look through the user list and click any red "failed migration" errors. Review the information and act accordingly.

    If problems persist, contact Support.

    Request Statistics

    Click the pie chart icon in the MigrationWiz dashboard to receive an email containing all the project migration statistics.

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