Microsoft 365 Tenant-to-Tenant Migration—Move Mailboxes, SharePoint & OneDrive Without Downtime

Explanation of Tenant-to-Tenant Migration?

It’s just a simple process in which a user moves their data and supported workloads from one tenant to another. To perform tenant-to-tenant migration properly, you may need to prepare identities, permissions, and dependencies.

For example, consider the situation

Whenever a company takes over another business, they may need to:

• Tenant A containing its existing users and data.
• Tenant B containing the acquired company’s users and data.
• A target environment where the organizations will eventually operate.

Note: The process may involve more things compared to just copying files and mailboxes. For this reason, Microsoft 365 Tenant Migration should be treated as a structured project.

Microsoft 365 Native Tenant Migration Options and Limitations

Microsoft’s current migration framework is not based on one tool for every workload. Instead, administrators can use Migration Orchestrator for coordinated user-level migrations or use dedicated cross-tenant migration capabilities for individual workloads. This process is important for organizations that migrate between multiple tenants.

About Migration Orchestrator

Microsoft’s Migration Orchestrator is a systematic approach to moving users’ data between tenants. It supports four workloads in an orchestrated migration batch:

For organizations handling multiple workloads together, Microsoft 365 tenant-to-tenant migration helps to maintain these things:

• Mailbox
• OneDrive
• Teams-related Dependencies

The orchestrator manages workload dependencies. For example, Teams meeting migration depends on a successful mailbox migration.

Admins or individuals who migrate from one tenant to another must therefore prepare the destination path before moving the data. Microsoft also recommends running multiple supported workloads together in the same batch when they belong to the same migration scenario.

The orchestrator does not migrate identities. Administrators must create and configure users in the target tenant and prepare them for migration. Microsoft also states that shared data such as Teams channels and SharePoint sites is outside the

scope of the Orchestrator. Those workloads use separate migration paths.

Microsoft’s current Orchestrator process uses validation, pre-cutover synchronization, and a cutover phase. Planning becomes crucial for providers that migrate between tenants because the source and destination environments have different types of configuration. During the pre-cutover phase, Exchange can synchronize mailbox data while users continue working in the source mailbox. The cutover then moves the user to the target environment.

Microsoft 365 Native Migration Options at a Glance

Native Migration Option	What It Covers	Key Points / Limitations
Migration orchestrator—mailbox	Email, contacts, calendar, tasks, notes	Preview feature: Outlook Outbox items don’t migrate (they’re stored locally, not synced to the cloud). Teams meeting migration depends on a successful mailbox migration first.
Migration orchestrator—OneDrive	Personal OneDrive files and folders	One-and-done—no incremental or delta passes, even under the orchestrator. A redirect is left at the source location until the source tenant is deprovisioned. Up to ~4,000 accounts can be queued per batch; not available on Government Cloud tenants
Dedicated cross-tenant SharePoint migration	SharePoint team/communication sites and content	Entirely separate from the orchestrator, classic workflows, Power Apps, and Power Automate Connections need to be recreated on target. Up to ~4,000 site migrations can be queued at a time; licensed by data volume rather than per use

 

None of this makes Microsoft’s native tooling a bad option—for a straightforward, smaller migration. It’s a legitimate, Microsoft-supported route still uses the older Exchange Admin Center + PowerShell batch process. It predates the orchestrator and remains fully supported.

But running different paths, different licensing models, and no shared dashboard is where the administrative piles up on projects. That’s the gap a dedicated migration tool is built to close. For such large environments, Microsoft 365 tenant-to-tenant migration can benefit from a single workflow.

Why Enterprises Choose the Aryson Tenant-to-Tenant Migration Tool

The Aryson Tenant-to-Tenant Migration Tool is a Graph API-based utility built to put that entire workflow in one place. Administrators can migrate Exchange Online, OneDrive, SharePoint, and Microsoft Teams with proper user mapping and run quickly. Highly selective migrations can also be done through advanced filters. They rely on incremental processing so large volumes of data don’t have to move all at once. Built-in duplicate detection and a dedicated monitoring dashboard round out the workflow.

Cross OneDrive and SharePoint Migration

The software allows users to migrate their OneDrive data to SharePoint, and vice versa is applicable as well. This eventually lets organizations move data between OneDrive and SharePoint as their storage and collaboration needs change.

What Aryson Microsoft 365 Tenant-to-Tenant Migration Can Perform

Workload	Supported Data
Exchange Online	Mailboxes, emails, contacts, calendars, and supported mailbox data
OneDrive	Files and folders with selective migration, file-type, size, and date-based filtering
SharePoint	Sites, document libraries, lists (generic lists), folders, and selective content migration
Microsoft Teams	Teams, channels, messages, replies, files, folders, Planner, Tabs, Apps, Loop components, reactions, mentions, quotes, meeting links, and supported collaboration content

 

Why Graph API Migration Is Better Than Legacy Approaches

Older migration tools leaned on IMAP, MAPI over HTTP, or EWS protocols. Microsoft has been deprecating or rate-limiting them for years. Graph API is the official integration for Microsoft 365 data, and for tenant migration specifically, it brings a few advantages:

• OAuth 2.0 authentication—no stored passwords, and it works with MFA.
• One permission model across Exchange, SharePoint, and OneDrive instead of three.
• Incremental sync support, which is what makes delta migration passes possible in the first place.
• Metadata preservation—sender details, timestamps, and folder associations survive the move.

Graph API limits you should know

It’s worth understanding the limitations of the Graph API-based approach. Standard user, shared, resource, and room mailboxes migrate cleanly. Group mailboxes and archive mailboxes need special handling and aren’t a simple drag-and-drop. OneDrive migrations won’t transfer those files that Microsoft’s malware scanning has flagged. SharePoint migrations move the core site content rather than custom code or full version history.

Key Features of Aryson Tenant-to-Tenant Migration

1. User Mapping: Once you authenticate the destination account, you just have to select the source and destination mailboxes for mapping. The rest of the mapping is handled by the software. Proper mapping is particularly important during Microsoft 365 tenant migration.
2. Selective Migration: You are allowed to select specific users and SharePoint libraries, lists, or OneDrive instead of migrating the whole tenant. Filters can also be applied by file extension, file size, and date range.
3. Incremental Migration: Enterprises have large volumes of data that they can migrate without any duplication. Even the Skip Previously Migrated Data option detects content that has been transferred and allows migration of the relevant data.
4. Duplicate Checking: It provides removal of duplicates for supported Microsoft 365 workloads. Duplicates can be compared using sender for emails and content-based comparison for SharePoint and OneDrive files.
5. Destination Paths: You can choose destination folders and paths to save migrated content wherever you want.
6. Authentication: The tool allows users to authenticate their tenants via modern OAuth and secrets to access the Microsoft 365 tenant.
7. Monitoring: After configuration is done, you can start the migration and verify transferred data.

How Aryson Tenant-to-Tenant Migration Works

1. Install and open the Aryson Tenant-to-Tenant Migration Tool with administrative rights
2. Select the OneDrive, SharePoint, or Mailbox option from the Home.

Note: You have to first sign in to your Microsoft account



3. Connect and authenticate the source and destination tenants.

   Once the connection is done, load data to migrate from one tenant to another

   
   
4. Select the workloads and data to migrate.
5. Map users and configure filters—by folder, site, date, file type, or size.

6. You can also apply filters and have options to attach attachments

   
   
7. Start the migration and monitor progress from the dashboard.
8. Review reports and verify the migrated data in the destination tenant.

Note: Thus, after following the above steps, you can perform your Microsoft 365 tenant-to-tenant migration smoothly. But the software has more to offer. It’s worth going through the detailed documentation of Aryson Tenant to Tenant Migration Guide to reduce the risk of data loss.

Difference Between Aryson vs. Microsoft Native Migration

Capability	Aryson M365 Tool	Native Microsoft
Exchange mailbox migration	✓ Batch, up to 5,000+	✓ Limited, PowerShell-heavy
SharePoint + OneDrive	✓ Single workflow	✗ Separate tools required
Calendar + Contacts	✓ Included	✗ Manual or unsupported
Delta / incremental passes	✓ Built-in	✗ Not available natively
MFA + OAuth 2.0	✓ Yes	✓ Yes
Teams migration	✓ Yes	✗ Separate product required
Deduplication	✓ Hash-based	✗ No
PST export alongside migration	✓ Unique capability	✗ No
macOS support	✓ Including Apple Silicon	✗ No
Free trial	✓ 50 emails/folder, 25 contacts	N/A — service-based

 

Some Examples of Migration Projects

For projects having multiple workloads and more users, Microsoft 365 tenant-to-tenant migration can be easier to migrate.

“5,200 mailboxes, no redos.” “We completed a cross-tenant migration involving more than 5,200 mailboxes, SharePoint sites, and OneDrive accounts during a merger. Not in one go, but in scheduled phases. Graph API-based processing kept data integrity solid; the delta feature meant our cutover weekend was two hours, not two days.” Michael H., IT Director, United Kingdom

“2,800 mailboxes, permissions intact“ “The filtering capabilities let us transfer only relevant data while preserving permissions, metadata, and folder hierarchy. We didn’t have to clean up a single misplaced mailbox post-migration.” Sarah T., Systems Architect, Canada

“4,000 accounts across departments“ “The incremental migration feature eliminated duplicate processing. Real-time reporting meant I could show stakeholders exactly what had moved and what hadn’t at any point during the project.” David R., Enterprise IT Manager, USA

 

What You Can and Cannot Do in a Free Trial

The trial version lets you run an actual migration—not just a UI tour. Here’s the scope:

What the trial includes	Limit
Mailbox emails per folder	500 items per folder
SharePoint / OneDrive files	Files up to 20 MB each
SharePoint list items	5 items per list
Contacts per mailbox	100
Calendar events per mailbox	100
Deduplication	Preview only—no deletion
Full version required for	Unrestricted migration at scale

 

The 500-items-per-folder limit is enough to validate the mapping, folder hierarchy, and authentication setup before buying. Run a demo of a test mailbox to see if your source and destination tenant connectivity works or not. Before buying the software.

Prerequisites and Supports

Software version	26.5 (updated June 2026)
Windows installer size	250 MB
Supported OS	Windows (10/11/8/8.1/Xp), Enterprise (E1, E3, E5), Business, Academic (A1–A5), Frontline (F1), and Exchange Online.
Authentication	Microsoft OAuth 2.0, Graph API, MFA-compatible
Internet required	Yes—Graph API calls to Microsoft 365
Admin permissions required	Microsoft 365 Global Admin or delegated admin with Exchange and SharePoint access

 

Let’s Conclude

A Microsoft 365 tenant-to-tenant migration is not only about data transfer. It’s more about user mapping, dependencies, permissions, etc., all happening together. For organizations that are moving multiple workloads at a large scale. They need a dedicated conversion tool that supports OneDrive, SharePoint, etc., together in one workflow. Allowing us to map users, make specific selections, remove duplicates, and provide live monitoring.

Frequently Asked Questions: