Exchange Online (Microsoft 365) Mailbox to Microsoft 365 Groups Mailbox Migration Guide

This is the complete onboarding task flow for migrating mailboxes from one Microsoft 365 tenant to another Microsoft 365 tenant.

This migration scenario is useful if you want to migrate data from individual mailboxes into shared Microsoft 365 Groups mailboxes. This migration scenario only supports the migration of mail items into the Microsoft 365 Groups.

First time?

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.


  • 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.
  • We are not able to support migrations with two-factor or multifactor authentication. 
  • App password usage is not supported by this endpoint. 
  • The maximum file size for migration through MigrationWiz varies by migration type and environment, but may never exceed 60GB.
  • Exchange Web Services (EWS) must be enabled for the mailboxes in the Exchange Online tenant for this migration type.


    MigrationWiz no longer supports Teams private chat history as part of Mailbox migrations due to Microsoft's restriction on Teams data access through EWS. For more information please review this article.
Which items are migrated?
  • Inbox
  • Folders
  • Email
  • Contacts
  • Calendars
  • Tasks
  • Journals
  • Notes
  • Server-Side Rules
  • Folder Permissions
  • Post (when the destination is Exchange or Microsoft 365)
Which items are not migrated?


  • Safe Sender/Block Lists
  • In-line images in Tasks
  • Private Chats
  • Calendar acceptance status emails

Groups Documents

  • Notebooks
  • Anything not in a document library (See SharePoint)

Prepare the Source Environment

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 source.

Create an Administrator Account

Create an administrator account in Microsoft 365 to be used for migration or use the global admin account for the tenant. The administrator account must have either full access to the user mailboxes or be granted impersonation rights. We recommend using impersonation as it will help reduce the likelihood of the migration being throttled by Microsoft. 

To manually enable impersonation for the source endpoint in your MigrationWiz project:

  • Click on Edit the Project and click on Advanced Options.
  • Click on the Source/Destination tab.
  • Under SOURCE: MICROSOFT 365, make sure the box named Use Impersonation to Authenticate is checked.
  • Click on Save Options.


When impersonation is enabled and a job is requested to be performed in the project, MigrationWiz will attempt to run a remote PowerShell command in the tenant to grant the Application Impersonation role to the admin account being used in the project. For this to be successful, the admin account in the project needs to be a global admin to have the required permissions to do so.

Microsoft 365 does not always respond on time for this process and can sometimes cause the job to fail in the project with an error regarding not having permission to impersonate the user being migrated.

If that is the case or the admin account being used in the project is not a global admin, then manually perform this task in the tenant using the steps outlined under Manually Grant Application Impersonation below (you may opt to proactively perform these steps ahead of time instead of having MigrationWiz do it)

Manually Grant Application Impersonation


The remote PowerShell commands below can take several minutes to complete.

  1. Make sure you are using a global admin account to perform these steps
  2. Click the Windows Start button.
  3. Search for Windows PowerShell (PowerShell should already be installed).
  4. Start PowerShell under an administrator context (right-click -> run as administrator).
  5. Run the following PowerShell commands one at a time:
    Set-ExecutionPolicy Unrestricted$LiveCred = Get-Credential

    Install-Module -Name ExchangeOnlineManagement
    Import-Module -Name ExchangeOnlineManagement
    Connect-ExchangeOnline -ConnectionUri -Credential $LiveCred


    The Enable command may take a long time to run and may error out. If so, wait a few minutes and run it again.
    New-ManagementRoleAssignment -Role "ApplicationImpersonation" -User
  • Make sure to replace "" in the PowerShell command above with the admin account being used for migration.
  • Ignore any errors such as "This operation is not available in the current service offer."
  • Ignore any errors such as "The assignment of the management role 'ApplicationImpersonation' [...] won't take effect until the user is migrated."

Prepare the Destination Environment

Modern Authentication Requirements

The steps listed in Authentication Methods for Microsoft 365 (All Products) Migrations 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.

Create Administrator Account

Create an administrator account in Microsoft 365 for the migration or use the global admin account for the tenant.

Create the Microsoft 365 Groups

This step is only necessary if the group does not already exist. Either of these options can create Microsoft 365 Groups:

Manage Group Membership

The following actions may be performed to manage group membership before migration.

  • Add members to the Group using the Microsoft 365 admin center.
  • Add migration administrator account as a member of the group.

  • Add migration administrator account as an owner of the group.

MSPComplete Steps

Create the customer

  1. Log in to MSPComplete.
  2. Click the Add button in the top navigation bar.
  3. Click the Add Customer button on the All Customers page.
  4. In the left navigation pane, select the appropriate workgroup and then click All Customers.
  5. Click Add Customer.
  6. Enter the new customer’s information in the Add Customer form. Primary Email Domain and Company Name are required. The rest are optional.
  7. Click Save.
  8. Repeat steps 1 through 4 for each customer you want to add. 

MigrationWiz Steps

Create the Mailbox Migration Project

You will now create the migration project and add your users.

Once a project is set up, you cannot add more users or make changes to the configuration except for advanced options. If you want to add users to the organization, please add them to the source before creating the project or add them manually to the destination. Once the project is created, users will be added to the project automatically from the source endpoint.

  1. Click the Go To My Projects button.
  2. Click the Create Project button.
  3. Create a Mailbox migration. 
  4. 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, a Customer 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.


Select an existing Microsoft 365 mailbox source endpoint, or create a new one. 

To create an endpoint: 

  1. Click Endpoints.
  2. Click Add Endpoint.
  3. Enter the endpoint name.
  4. Select endpoint type Office 365.
  5. Complete the Application (client) ID and the Directory (tenant) ID fields.
    Source Settings.png
  6. Click Next Step.


Select an existing destination endpoint for Office 365 Groups mailbox or create a new destination endpoint.

  1. Click New.
  2. Name the endpoint.
  3. Select type Office 365 Groups. If your endpoint is GCC High, select Office 365 (US Government) for your endpoint.
  4. For the URL field, enter the tenant's SharePoint top-level site URL.
  5. Enter the admin account credentials.
  6. Click Add.
  7. Complete the Application (client) ID and the Directory (tenant) ID fields.
    Destintation Settings.png
  8. Click Next Step.
  9. Click Save and Go to Summary.

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.

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 User Accounts

Add the user accounts that will be migrated to the project. This may be done in several ways, depending on the size of the project. Steps for each option are in the accordion below, simply click to show the option you select and follow the guidance there.

Small Migrations

For small migrations, it is easy to add users one at a time using Quick Add. The steps for this are below. 

Larger Migrations

For larger migrations, we recommend either using the Autodiscover or Bulk Add option.

Quick Add
This option allows you to add items one at a time. To do so, you only have to provide an email address if you entered administrative credentials when setting up the project. If you did not, enter the following user information:
  • An email address
  • Login name
  • Password
  • Mailbox status
Bulk Add

MigrationWiz allows you to bulk import mailboxes into the system.

To import one or more mailboxes:

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

Export the user list to a CSV file

You can copy and paste the user list into the Source and Destination Email columns within your MigrationWiz project dashboard under Add > Bulk Add.

To export the user list:

  1. Go to the Microsoft 365 admin portal.
  2. Click Users.
  3. Click Active Users.
  4. Click Export.
  5. Click Continue.

Be sure to save the CSV somewhere you can access it for upload later in the migration.


Autodiscover process within MigrationWiz can be used to discover items from the Source environment so that they can be imported into your projects. This can then be edited in the project to remove users not being migrated. All users are added with the source and destination email addresses set to match the source email.

This can be changed by using the Change Domain Name button at the top of the project page. If the usernames are changing during the migration, we recommend using the Bulk Add option.

There are a few requirements for this to work:

  • The Source has to be Exchange 2007 or later, or Microsoft 365, or G Suite. If you are using Autodiscover from G Suite, all G Suite domains must be added to the list of domains in the Endpoint.
  • The endpoint on the Source needs to use admin credentials.
  • For mailbox migration projects, the admin account that is specified within the Source endpoint needs to have a mailbox associated with it.
  • The admin mailbox must be listed in the public Global Address List (GAL).
  • The migration project type needs to be a Mailbox migration. For the exact steps to be followed during your migration, refer to the relevant Migration Guide. All Migration Guides can be found on the Help Center site.

One additional item to note here is that there is no way to restrict the IP addresses that the connection will come from.  This means that the steps outlined in our IP Lockdown guide will not apply here.  If your environment requires that any IP addresses be whitelisted, it is recommended that items be added to your project using one of the other available options.

Autodiscover of items will not work while using Modern Authentication

Autodiscovery exposes the following items:

  • For mailbox migration, autodiscovery will list all mailboxes at the Source.

Steps to Run Autodiscover

  1. Navigate to the project you want to import users into.

  2. Ensure that you have created an endpoint for the source project.

  3. Once in the project, on the top navigation bar, click on the Add drop-down, then select Autodiscover Items. This will begin the Autodiscover process.

  4. Once discovered, click on the Import button, to import the items into your MigrationWiz project.

Advanced Options

The following option is the most valuable for this migration scenario.

Support Tab

Default Options

The client and tenant ID fields for source and 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.

Advanced Options.png


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

Source/Destination Tab

At the Source/Destination tab in the advanced options of the project, under DESTINATION: MICROSOFT 365, uncheck the box labeled Use Impersonation to Authenticate. This option does not work for Office 365 Groups If you do not uncheck this box, the migration will fail.

Filtering Tab

  •  ^(?!Inbox$). This RegEx expression migrates the Inbox, but not its subfolders. To migrate both the Inbox folder and Calendars folder, use instead the RegEx expression ^(?!Inbox$|Calendar$). These filters are used to prevent failures, as Groups should only contain an Inbox folder, and possibly a Calendar.  No other folders are supported. This expression must be in the source language, such as ^(?!Boîte de réception$) for French.

Run Verify Credentials

You may verify the credentials of items in MigrationWiz without migrating data or consuming any licenses.

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

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


Purchase and apply User Migration Bundle licenses for all the users being migrated. For this migration type, we suggest the User Migration Bundle.

  • User Migration Bundle Licenses have unlimited data available per license.
  • User Migration Bundle Licenses are applied to the customer's users and expire 12 months after their purchase date. 
  • Document, Personal Archive, and DeploymentPro projects are all included when using User Migration Bundle Licenses.
  • This license type must be applied manually.

Purchasing Licenses

  1. Sign in to your BitTitan account. 
  2. In the top navigation bar, click Purchase.
  3. Click the Select button and choose the license type you need.
  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.

Applying User Migration Bundle Licenses

  1. Sign in to MigrationWiz at
    • You can either sign in and make sure to select the MigrationWiz button above the email field or sign in to the MSPComplete page, then click the All Products button and select MigrationWiz.
  2. 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. If the project was not created under your account, your account must be part of the workgroup and project sharing must be enabled. 
  3. Click the project that requires licenses to be applied.
  4. Check the box to the left of the email for the user(s) to whom you want to apply for a User Migration Bundle license.
  5. Click the More menu (3 stacked lines) at the top of the project page.
  6. Click Apply for User Migration Bundle License.

If you have more questions about licensing, including redeeming coupons, or changing categories, see MigrationWiz Licenses.

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.

Notify Users

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

MX Record Cutover

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

Send an email to end users to let them know what to expect for their Outlook profile reconfiguration. 

Run Migration

You are now ready to run the migration. 

  1. Select the users.
  2. Click the Start button from the top.
  3. Select Full Migration.
  4. Select to migrate Mail only.
  5. Click Start Migration.

Run Retry Errors

Look through the user list and click any red "failed migration" errors. Review the information and act accordingly. Each error logged represents an item that was not migrated. MigrationWiz contains a mode in which you can resubmit the migration to retry failed items. This mode of operation is always free of charge. You may only submit mailboxes in this mode only if they satisfy all of the following conditions:

  1. The last migration pass was completed successfully.
  2. The mailbox contains at least one error.

If your mailbox does not satisfy these conditions, you will receive a warning when submitting the migration in this mode and your request will not be fulfilled.

To submit one or more mailboxes in retry mode, perform the following steps:

  1. Sign into your MigrationWiz account.
  2. Click the Go To My Projects button.
  3. Select the project that contains the mailboxes that you want to retry.
  4. Select the mailboxes that have migration errors.
  5. Click on the Start button.
  6. Select Retry Errors from the menu.
  7. Click the Retry Errors button.

When errors are repaired, they will disappear from the error log. Some errors may not disappear if the Source item was not reprocessed (due to filters, for example), has been deleted or moved, or if the item failed again. 

If problems persist, contact Support.

Post Migration

  • Show users how to access the Microsoft 365 Group; this will appear in their Outlook, under Groups.
  • Click the pie chart icon in the MigrationWiz dashboard to receive an email containing all the project migration statistics.
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