Tested Microsoft Migration Orchestrator: What It Really Does, Its Limitations & What You Should Know

Written By Eva Shirley
Approved By Shivam Rathore
Publish on September 11th, 2026
Reading Time: 12 minutes

User Query:

A few months back, one of our senior engineers in Pune spent a full weekend trying to move a test batch of mailboxes between two Microsoft 365 tenants using Microsoft’s own Orchestrator tool. On Monday, he came up with a positive outcome and a negative one.

The capability of Microsoft Migration Orchestrator to migrate workloads between tenants was the major advantage. However, its strict requirements and limitations make it work well only for certain migration projects. Then, which migration method should one go for?

Summary: Microsoft 365 tenant-to-tenant migration becomes necessary when an organisation moves users and data from one Microsoft 365 tenant to another. Organisations often need to migrate tenants when a company merges or acquires another organisation or performs tenant consolidations. This migration involves the mapping of identity mapping, licensing, dependencies on workloads, scopes, and post-migration configurations.

To accomplish this migration, a segment of users may prefer Microsoft’s own Orchestrator tool, while some opt for the Aryson Tenant to Tenant migration tool. In order to remove any kind of further confusion regarding the ideal method to choose, this blog is written. Therefore, read this article to the end to choose the suitable method as per your requirements.

Download Now Purchase Now

Scenarios Where Organisations Perform M365 Tenant-to-Tenant Migration

A tenant-to-tenant migration moves Microsoft 365 users and supported workloads from one Microsoft 365 organisation to another.

The requirement commonly appears during:

Mergers and acquisitions
Business divestitures
Company rebranding or restructuring
Tenant consolidation
Organisational separation
Internal business-unit migrations

For example, a company acquiring another organisation may need to move selected users from the acquired company’s Microsoft 365 tenant into its existing tenant. A divestiture may require only a portion of the source tenant’s users and data to move to a new organisation.

How Do Industries Shape Tenant-to-Tenant Migrations?

India’s three busiest M&A hubs perform cross-tenant migrations in a completely different workflow.

Mumbai and Pune: The banking sector & BFSI companies very frequently merge or restructure. Their major concern is to follow the RBI and SEBI requirements for data location, security, and audit records.

Hyderabad: Pharma companies deal with sensitive information and confidential documents; as a result, it is important to move permissions and access settings carefully.

Chennai: Whereas the automotive companies located in Chennai perform tenant move/split, rather than moving everything into a new tenant all at once.

Thus, every industry, and so the migration, differs from one another. What matters to a particular industry during migration might not have a large impact in any other sector. In line with this, the scope, identity strategy, workload dependencies, and coexistence requirements can differ significantly.

*Tenant move/split refers to moving only a certain part of a Microsoft tenant, rather than the entire tenant altogether. This usually takes place when an organisation sells a part (department) of its organisation to another organisation.*

These differences eventually affect the migration approach an organisation should choose. Microsoft’s own Orchestrator tool may work for some workflows. Whereas for others, dedicated software offers the required results.

What Does the Microsoft Migration Orchestrator Actually Do

The primary purpose of a Microsoft 365 Migration Orchestrator is to migrate multiple workloads from one tenant to another.

So, instead of considering each workload as a completely different project, administrators may create migration batches that hold multiple supported workloads – then let the Microsoft 365 Orchestrator take care of necessary sequencing.

The supported workloads are:

Exchange Online mailboxes: emails, contacts, calendars, tasks, and notes.
OneDrive: users’ OneDrive files
Teams chats: chat history and related meeting information
Teams meetings: migrated meeting information.

Keep it noted: The Orchestrator tool can only migrate content, not user identities. Therefore, in order to do the same, administrators need to create and prepare users in the target tenant all by themselves.

Migration Architecture Models Offered By Orchestrator

For each organisation, the Microsoft 365 Tenant Orchestrator migration requirements and concerns differ. Therefore, a common migration architecture may not support the needs of each tenant migration project. The orchestrator supports three different models to help organisations decide the workflow.

Migration model	Simple meaning	Suitable for
Single-event migration	Migrate every workload in one major migration	For migration of small data sets
Phased migration	Include the migration of users in groups over several stages	Large-scale organisations
Tenant move/split	Migrate only a specific number of users to another tenant	Divestitures or reorganisations

You may select an appropriate model on the basis of the total number of users, the data volume of the workload, and the business structure. The choice of migration model might vary whether the organisation goes through a consolidation or divestiture.

*It is recommended for large organisations to avoid migrating the entire tenant all at once. Rather, they should consider making groups of users and migrating them in different stages (i.e., phased migration). This eventually makes it easier to review the identity mapping, workload behaviour, mail routing, Teams access and UX before migrating the next group.*

Orchestrator Moves Content, Not Identities

One of the most important points to understand before using Migration Orchestrator is that it does not create and migrate user identities automatically as part of the content migration.

Users must be prepared in the target tenant before migration.

For supported orchestrated migrations, the target user must exist as a MailUser (Mail-Enabled User) with the appropriate attributes and identity mapping. Microsoft specifically requires identity mapping to be completed before Exchange or OneDrive licenses are assigned to the target users.

The target user should not already have a provisioned Exchange Online mailbox when the migration is being prepared. Assigning Exchange Online or Teams licenses too early can cause the target account to become a mailbox user instead of the required MailUser object.

The target preparation therefore needs to cover:

Creating the target users.
Performing identity mapping between source and target users.
Ensuring the required Exchange Online and Teams licensing is available.
Preventing premature OneDrive provisioning.
Preparing the required groups and permissions.
Verifying the identity mapping before beginning migration batches.

Identity preparation is one of the areas where a technically correct migration plan can make a major difference to the outcome.

Licensing Requirements

Cross-tenant migration requires a per-user licence. The licence can be assigned to the user’s source or target account. Licensing should be confirmed before creating migration batches.

Microsoft requires a Cross-Tenant User Data Migration (CTUDM) licence for supported cross-tenant user-data migrations. The licence is associated with the migration user and can be assigned on the source or target side according to Microsoft’s current licensing requirements.

This licence is an add-on to the other subscription plans:

Microsoft 365 Business Basic, Standard, and Premium
Microsoft 365 F1/F3/E3/E5
Office 365 F3/E1/E3/E5
Exchange Online
SharePoint in Microsoft 365
OneDrive
EDU

The licence supports the migration of cross-tenant mailbox migration and OneDrive migration.

*Administrators should not assume that one migration licence covers every Microsoft 365 workload. Teams chat doesn’t require a per-user add-on. SharePoint tenant-to-tenant migration is a separate capability and has its own licensing considerations.*

Licensing should therefore be mapped against the actual migration scope before the project begins rather than after batches have already been prepared.

What Microsoft Migration Orchestrator Doesn’t Migrate?

Understanding what is outside the Orchestrator scope is just as important as understanding what it supports. Orchestrator should not be treated as a complete tenant-copying solution.

Workload	What Doesn’t Migrate?	Impact on the Project
SharePoint Sites	SharePoint sites and their shared data are not covered by Orchestrator.	Requires separate SharePoint migration planning and execution.
Teams Channels	Teams channels and their channel-based data are not covered by the Teams chat workload.	Organisations with channel-based collaboration need a separate migration approach.
Shared Channels	Not Covered	Shared-channel content requires separate assessment and migration planning.
Microsoft 365 Groups	Groups and their related structures are not covered as an Orchestrator workload.	Group creation, membership, and related configurations may need separate handling.
Power Platform	Power Apps, Power Automate, and related Power Platform configurations;not covered.	Requires separate migration or recreation planning.
Planner	Planner data is not covered by Orchestrator.	Plans and related data require separate migration planning.
Microsoft Forms	Forms data and configurations are not covered.	Forms may need to be migrated or recreated separately.
Microsoft Stream	Stream data is not covered.	Stream content requires a separate migration approach.
Yammer	Yammer data is not covered.	Yammer content and collaboration require separate planning.

Here’s What Nobody Tells You

There are certain points that get unnoticed when you consider Microsoft’s Cross-Tenant migration Orchestrator to migrate tenants. It is crucial to consider them to make sure you perform the data transfer without any further issues.

Shared data remains in the source tenant: Data associated with workloads outside the Orchestrator scope is not automatically moved to the target tenant.
No real delta synchronization: OneDrive is a one-time migration and does not continuously re-sync changes made afterward.
Failed mailbox migrations may require reruns: When mailbox migration errors occur, the affected mailboxes may need to be recreated or rerun rather than being automatically re-synchronized.
Legal and eDiscovery holds: Mailboxes under legal hold or eDiscovery hold cannot migrate until the applicable holds are resolved.
Sensitivity labels: Sensitivity labels do not transfer with the migrated content. Labeled content may need to be handled before migration and labels reapplied afterward.
Mailbox batch limit: Mailbox migrations support batches of approximately 2,000 users.
Teams batch limit: Teams chats and meetings have smaller batch limits of approximately 100 users.
Workload sequencing matters: Teams meetings have dependencies on the related chats and mailboxes. Selecting meetings without the required workloads can prevent the migration batch from starting.
Teams chat and OneDrive sequencing: Moving Teams chats prior to OneDrive migration may result in chat file attachments still referencing the original tenant – potentially leading to broken links post-migration.
Email signatures: Email signatures do not migrate and may need to be recreated in the target tenant.
Delegate permissions: Certain delegate permissions do not transfer and may require separate configuration.
Path and Storage Limits: OneDrive and SharePoint migrations are subject to Microsoft-defined limits. Administrators should check:

Number of items
Storage size
File and folder paths
User and site URL lengths
Existing target OneDrive or SharePoint site.

Microsoft currently documents a 400-character path limit for relevant SharePoint and OneDrive migration scenarios.

A target URL that is longer than the source URL can therefore cause an otherwise valid migration to fail because the combined path exceeds the supported limit.

Aryson Tenant Migration Tool vs M365’s Orchestrator Tool

Considering the above limitations of the Microsoft migration Orchestrator tool, organisations prefer to use the Aryson Tenant to Tenant Migration tool. They first follow the Microsoft 365 migration checklist and use one of the methods mentioned below.This might take place due to various reasons tabulated below.

Features	Microsoft Orchestrator Tool	Aryson Tenant to Tenant Migration Tool
SharePoint Migration	❌	Migrates SharePoint sites, document libraries, files, folder hierarchy, and supported metadata as part of the same cross-tenant migration solution.
Deduplication	❌	Deduplication for Exchange mailbox, OneDrive, SharePoint, and Teams
Teams Channels	Teams channels and shared-channel content are not covered by the Teams chat workload	Supports Teams and channels, including channel structure, messages, files, folders, Planner, tabs, and apps
OneDrive Incremental Migration	Cross-tenant OneDrive is a one-time process and does not provide incremental/delta passes.	Provides incremental migration and can skip previously migrated files, emails, or content so that only new or missing data is transferred.
User & Folder Mapping	Requires source-to-tenant identity preparation & mapping	Provides automated user, mailbox, Onedrive and SharePoint mapping
Migration Monitoring & Reporting	Requires tracking migration status and failure	A centralised dashboard, migration reports, activity logs and monitoring
Cross-Storage Migration	❌	Provides OneDrive->SharePoint and vice versa.
PST Export	❌	Aryson can export mailbox data to PST, with folder mapping and options to split large PST files by size or date range.
Attachment Control	Native migration does not provide the same attachment-level migration controls described for Aryson.	Lets administrators include, exclude, or customise attachment transfer according to project requirements.
Migration Without PowerShell	Can involve configuration and administrative setup.	Aryson provides a Graph API-based migration workflow without PowerShell, with automated mapping and a graphical interface

Apart from this, there is a lot more to do with the Aryson Tenant-to-Tenant Migration, the Software Guide interface and functionalities. Refer to the complete documentation of this utility to explore the software in a better manner and effortlessly migrate workloads.

Post-Migration Changes Made to the Source Mailbox

After a successful cross-tenant mailbox migration, the source mailbox is no longer the active mailbox for the migrated user. The source object is converted to a MailUser so that mail routing can continue toward the target mailbox. This is why administrators need a clear mail flow and rollback strategy before the cutover.

The source objects should not simply be deleted immediately after migration. Microsoft also recommends maintaining the required mail forwarding and source objects until the tenant migration process is complete, particularly where batches and migrated meetings are involved.

Final Takeaway

There are different considerations about the Microsoft 365 migration using Microsoft migration Orchestrator. In the above blog we discussed how simple it is to migrate workloads by coordinating supported workloads in a single workflow. However, this tool doesn’t copy the entire tenant. Therefore, in order to migrate exchange mailboxes, OneDrive, Teams and chats, you may use the Aryson Tenant to Tenant migration tool. This Graph API-based utility comes with 24/7 personalised assistance to help you with migration if you encounter any queries.

Frequently Asked Questions

Q1. Does Microsoft Migration Orchestrator migrate Teams data?

Ans: Yes, Microsoft Migration Orchestrator supports Teams chats and meeting information. However, it does not migrate Teams channels, shared channels, channel files, Planner data, apps, or other Teams-connected workloads. These require separate planning or a dedicated migration solution.

Q2. Is Microsoft 365 tenant-to-tenant migration possible without downtime?

Ans: Microsoft 365 tenant-to-tenant migration can be planned to minimise user disruption through phased migration waves, coexistence, and proper mail routing. However, complete zero downtime depends on factors such as identity mapping, workload dependencies, DNS changes, licensing, and post-migration configurations.

Q3. What are the main limitations of Microsoft Migration Orchestrator?

Ans: Migration Orchestrator supports Exchange Online mailboxes, OneDrive, Teams chats, and meetings only. It does not cover SharePoint sites, Teams channels, Microsoft 365 Groups, Power Platform, Planner, Forms, Stream, or Yammer. In order to migrate SharePoint sites and Teams, you can use the Aryson Tenant-to-Tenant Migration tool.

Q4. Is Microsoft’s Migration Orchestrator enough for my Microsoft 365 tenant-to-tenant migration?

Ans: It depends on the project scope. Orchestrator can work well when only supported workloads need to be migrated and all prerequisites are met. However, organisations requiring SharePoint migration, Teams channels, incremental migration, deduplication, automated mapping, or broader workload coverage may prefer the Aryson Tenant to Tenant Migration Tool.

About The Author:

Eva Shirley

Eva Shirley is a skilled technical content writer with expertise in creating engaging and informative content. With over 5 years of experience and a passion for writing, she has solved many users' queries by providing quality content.