Microsoft 365 Tenant-to-Tenant Migration TEC Talk Recap

In April, we hosted a TEC Talk with over 450 attendees interested and engaged in the topic of Office 365 tenant-to-tenant migration.  Tenant consolidation projects due to mergers, acquisitions, and clean-up initiatives are not new, but they are ever-increasing in complexity as Microsoft adds more interconnected capabilities and services.  In this TEC Talk, I focused on the lessons I’ve learned over the years helping organizations consolidate their tenants while also covering the latest guidance. 

This webcast was part of our TEC Talk series, which focuses on providing practical and relevant information on a Microsoft 365 or Hybrid Active Directory topic without the marketing fluff. TEC Talks are a preview of what attendees can expect at The Experts Conference 2022 in Atlanta, September 20-21:.

The high attendance and active chat are testaments to the challenges IT pros are facing in this space.  In this article, I will review the top lessons learned and answer the open questions.

Current Challenges in Office 365 Migrations

Office 365 tenant-to-tenant migrations have several challenges.  Mergers, acquisitions, and divestitures are complex business transitions.  There is a lot of pressure to make the most of these investments.  However, even years into tenant-to-tenant migrations, we struggle with some common problems.

Intense growth in Office 365 customers, data, and features create increased complexity in these migrations.  New features are continually being released, but updates to migration APIs are not keeping pace. This leads to a shortage of native migration options for most workloads and limited APIs, causing systems administrators to fight a constant battle to keep up.  In the session, we dove into finding the pace of running your project.  We covered all the inputs, including determining your organization’s appetite for risk and the importance of protecting your migration window.

Microsoft Teams Migration Tips

Most tips for a Microsoft Teams migration follow the same patterns as those for other workloads.  The most obvious one is to be vigilant. Every migration has tight timelines, so you need to be realistic about what you are trying to achieve and when.

With timelines in mind, another tip is to focus the investigation, reporting, and scoping on the most used and largest Teams.  Dive into the details of the most active and largest Teams by data volume.  These “VIP” teams need focus as they are likely to have the largest impact on your organization if something goes wrong.  You may want even to consider user interviews to ensure you know how they are being used and their impact on the business.  Ask owners to set up certain items that should not be migrated.  By engaging early for the most active Teams, you can be more comfortable that the right data was migrated and was not lost during the migration process.

Keeping with the time theme, another tip is to protect your migration window.  You can do this by:

  • Pre-syncing whatever data you can.
  • Omitting low usage or archive Teams during your migration window
  • Limiting the amount of chat you migrate and consider options to migrate old chat to a text file time

These tips will reduce the amount of work that needs to be done in the maintenance Windows and increase your chances of a successful change Window.

For a refresher of this part of my TEC Talk, check out the recording.

Microsoft Platform Migration Planning and Consolidation

Simplify migration planning, overcome migration challenges, and finish projects faster while minimizing the costs, risks and disruptions to users.

TEC Talk Questions Answered

Question 1: Our users have hybrid joined workstations.  We’re not moving the users’ computers when we migrate their Office 365 content.  Because of this, they are getting TPM errors after they point to the Office 365 tenant.  How can we avoid these errors? 

Answer:  This error is common when users are running Click-To-Run Office.  To resolve this, you need to reset the Office Install properly.  Many migration vendors execute this with their reconfiguration agent to avoid these issues, including Quest On Demand Migration.  If you need to do it manually, Microsoft has a good KB article

If you choose to automate this yourself, note that some aspects of this script need elevated permissions, and other aspects need to run under the context of the logged-in user.

Question 2: The largest challenge I have been facing is migrating 1:1 chats from one Teams tenant to another.  Is there a clean and concise way to accomplish this? 

Answer: I agree. This is perhaps the most significant challenge right now in Office 365 tenant-to-tenant migrations.  Each chat and reply needs an API call to preserve all the chat metadata.  Otherwise, you could use other methods which don’t include preserving the message’s metadata.  The best advice in a Teams migration is to try to limit the amount of chat that is being migrated.  Some tools only let you migrate the previous two weeks in the format with metadata and migrate the rest to a text file.  Reading 1:1 chat often isn’t the issue; writing is.  This flexibility allows for the most recent work data to migrate over quickly, but the other items go into a format that is quicker to migrate.

Some of the APIs are premium APIs, meaning they have charges.  When evaluating your options, understand the costs and limits, and how they apply to your organization’s needs.

Read more: Microsoft Teams Private Chat Migration Challenges Explained

Question 3: Do you have any recommendations on migrating inactive mailboxes, deleted SharePoint sites, and OneDrives? 

Answer: In terms of terminated and deleted user content, you have two significant options.  

Export and Preserve: If you are trying to migrate this data because you are retaining it on litigation hold / for a litigation need, you may choose to just simply collect and export this data.  This data can then be re-imported into your organization’s tooling used for these kinds of situations. 

Other purposes: If you are retaining this data for other purposes, or this terminated user data / deleted site data needs to be migrated over, you have both a technical and a licensing issue.  At a basic level, you will need to reactivate the accounts and sites to migrate them.  Reactivation will consume licensing, so you need to make a plan with your Microsoft account team to handle these inactive accounts.  In theory, you will safely reactivate the accounts, license them on both sides, migrate them, and then re-delete them on both sides.  Be sure to check your target retention policies carefully!  Check with your Microsoft account team or license reseller to understand the options available to you, as there are limits on how fast you can re-use licenses. Organizations with Enterprise Agreements (EAs) tend to find more flexibility in their team if it is tied to a merger, acquisition, or divestiture.

Read more: The Three Keys to a Successful OneDrive and SharePoint Migration

Question 4: Are there tools that manage and ensure proper transfer of accounts on legal hold in compliance? 

Answer: The simple answer is, sadly no.  You will need to understand what holds are in the source.  If you are using eDiscovery Premium (formerly known as Advanced eDiscovery and recently rebranded to Microsoft Purview Premium), you need to understand what holds are in the source and/or target.  Regardless of your options, most will follow this process:  

  1. Ask Legal and Compliance to confirm all active holds are, in fact, active and if there should be others. 
  2. Provision your target account as you normally would.  Put the user on full litigation hold for the workloads in scope. For more details see this Microsoft article on legal holds.
  3. Migrate the content and confirm it is all complete.
  4. If you used premium hold features (tags, filtering, advanced indexing) you will need to recreate them.  You should then carefully remove the broad holds, ensuring you are testing and doing it correctly!

Read more: How to Create a Communication Compliance Policy

Question 5: At the risk of getting heckled out of here, what is the unique selling point of using a third-party tool such as Quest rather than the native migration options?  Are they still too immature? 

Answer: No heckling here!  I covered this in detail at a user group in Manchester UK a few months back.  At a high level, native tools, as of writing this, mainly remain in preview programs.  Preview programs have limitations in support and are difficult to truly rely on for significant projects.  In cases where migrations must happen in their migration window, this adds a lot of risk.  The other aspect is most of the migration work is done with a lot of different tools instead of using one migration tool.  In addition to all this, even in preview, not all data has a migration tool, including Microsoft Teams.  This forces most organizations to leverage office 365 tenant to tenant migration tools for at least some of their workloads.  

It would be best to look at the total cost of your projects when doing your analysis.  This needs to include the effort of using the tooling, features, licensing, and cost to operate.

Read more: Prepare an Office 365 migration plan assessment using PowerShell


Mergers, acquisitions, and divestitures are a permanent part of doing business today.  These require Office 365 tenant-to-tenant migrations. Because these migrations are becoming increasingly complex, it’s important to stay informed about Office 365 new features, new challenges, and tools available to facilitate smooth migrations. For in-depth training on Microsoft 365 migrations, you don’t want to miss The Experts Conference in Atlanta, September 20 -21, 2022. Explore the agenda and register early to save your spot.

Microsoft Platform Migration Planning and Consolidation

Simplify migration planning, overcome migration challenges, and finish projects faster while minimizing the costs, risks and disruptions to users.

About the Author

Mike Weaver

Mike is a Senior Product Manager at Quest.  Mike specializes in Office 365 tenant-to-tenant migrations and PST migration projects. With a wealth of experience in mergers, acquisitions, and divestitures (MAD), Mike often writes about technology solutions and personnel considerations to ensure both successful integration and adoption.  Mike can also be found on Twitter (@MADMike_365) or from time to time on his blog (

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