Microsoft 365 Group to Microsoft 365 Group Mailbox (Conversations) Migration Guide

This guide is for Microsoft 365 Group to Microsoft 365 Group Mailbox (Conversations) migrations, and is meant to work in conjunction with the SharePoint to SharePoint Migration Guide (Including Microsoft 365 Groups) if group file migration is also required.

There are some tools and resources that will make the migration easier.

First migration?

While this guide includes all steps required, migrations are complex projects that require a lot of planning ahead of time. We’ve created a guide on scoping, planning, and managing the migration process for your use. If this is your first migration, we recommend reading this guide 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. 

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

The maximum file size for migration through MigrationWiz varies by migration type and environment, but may never exceed 60GB.

Below is a list of items that are and are not migrated with this type of migration project. This list changes frequently, so review this list before any and all migration projects.

What items are and are not migrated?


  • Inbox
  • Email
  • Primary Calendar
Not Migrated
  • Safe Sender/Block Lists
  • In-line images in Tasks


Not Migrated

  • Notebooks
  • For Groups documents: anything not in a document library (See SharePoint)


  • Some group conversations might not be nested at the Destination.
  • The group OneNote notebook is not migrated.
  • We are not able to support migration endpoints that use admin accounts with two-factor or multifactor authentication enabled. 
  • Only the Inbox and Calendar folders are migrated for this migration scenario. Folder filters will need to be added to your project. The folder filters are covered in the steps for adding advanced options in this guide.

Prepare the Source Environment

  1. Create an administrator account in Microsoft 365 to be used for the migration, or use the global admin account for the tenant. 
  2. Add the migration administrator account as an owner and a member of the source group. 
  3. Make note of the owners and members of the group. You will need this information later when replicating the membership of the Source group at the Destination group.

Prepare the Destination Environment

  1. Create an administrator account in Microsoft 365 to be used for the migration, or use the global admin account for the tenant. 
  2. Create the Office 365 Group, if it doesn't already exist. 
  3. Add the migration administrator account as an owner and a member of the destination group. 
  4. Add other owners and members to the group to replicate the membership of the Source group.

MSPComplete Steps

Create Customer

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

Purchase licenses

For Group conversation migrations up to 50GB, we recommend using the Mailbox Migrations license. For any migrations over that amount, a User Migration Bundle license will be required. 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 the appropriate license for your migration
    1.  Mailbox Migration licenses for migrations under 50GB
    2. User Migration Bundle licenses for migrations over 50GB.
  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.

MigrationWiz Steps

Create a Mailbox Migration project

  1. Click the Go to My Projects button.
  2. Click the Create Project button.
  3. Select Mailbox Project for the type of project to create.
  4. Click Next Step.
  5. Enter a Project name and select a Customer.
  6. 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.

  1. Select an existing source endpoint or create a new endpoint. To create a new source endpoint:
    1. Click New.
    2. Name the endpoint.
    3. Select type Office 365 Groups.
    4.  For the URL field, enter the tenant's SharePoint top-level site URL.
    5. Enter the admin account credentials.
    6. Click Add.
  2. Click Next Step.
  3. Select an existing destination endpoint or create a new destination endpoint. To 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.
  4. Click Next Step.
  5. Click Save and Go to Summary.

Add Items

Add the Source and Destination group email addresses. This may be done in several ways, depending on the size of the project. 

Small Migrations:

For small migrations, it is easy to add users one-at-a-time using Quick Add. This option allows you to add items one at a time. You have to enter an email address, login name, and password for each user if you didn't enter administrative credentials when setting up the project. You only have to provide an email address if you entered administrative credentials when setting up the project.

Larger Migrations:

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

Bulk Add uses a CSV containing the source and destination email addresses for the O365 Group mailboxes to add to the project.

To import one or more Microsoft 365 Group 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

Apply Licenses

Apply User Migration Bundle licenses to all email addresses in the migration project. 

  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 and project sharing must be enabled, if the project was not created under your account.
  2. Click the project that requires licenses to be applied.
  3. Check the box to the left of the email for the email addresses to whom you want to apply a User Migration Bundle license.
  4. Click the More menu (3 stacked lines) at the top of the project page.
  5. Click Apply User Migration Bundle License.

Set the project Advanced Options 

Navigate to Support Options in your MigrationWiz dashboard and add the following:

  • Under Filter Folders: ^(?!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.
  • Add: RecipientMapping=">". Replace "" and "" with your actual domain names. This performs a find-and-replace that updates email addresses from one domain name to another. Use this support option when migrating mailboxes from an old domain name to a new domain name. If the email address of the users stays the same after the cut-over, this option is not needed.
  • Important: "Use Impersonation to authenticate" must NOT be checked in the advanced options for the source or destination the migration will fail. This setting is found under the Source/Destination tab in the advanced options of the project.

Run Verify Credentials

  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.​ 

Run Migration

Notify users

Notify users that a migration is occurring. Send an email to all users telling them the time and date of the migration and let them know what to expect for their Outlook profile reconfiguration. Samples and screenshots can be found in our DeploymentPro documentation if you are utilizing that tool. 

Full pass

Important: Under the Select what to migrate section, ensure that only Mail is selected before starting the migration. You may also select calendars. 

  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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