Cross Tenant Migration Microsoft 365: Best Practices & Requirements

Core Architecture of M365 Cross-Tenant Migration

Migrate email between two Microsoft 365 Tenants is a crucial step when transforming businesses. Enterprises need to migrate hundreds or thousands of users with data in TBs and business-critical work across Exchange Online, Mailboxes, SharePoint, and OneDrive. Therefore, it becomes essential to preserve productivity and data fidelity during the migration. 

Hence, to ensure that you can reduce migration risks during a Microsoft 365 tenant transfer, effective solutions are essential. This brings us to the two key migration solutions, i.e.:

• Native Microsoft Solution: Ideal for users with technical proficiency and expertise in PowerShell cmdlets. 
• SysInfo Microsoft 365 Migration Tool: A standardized method for large-scale migrations with granular control, better reporting, and automatic handling. 

To find out how to perform the migration appropriately, follow the step-by-step methods as explained here. But before that, ensure to fulfil the prerequisites as stated below. 

Pre-Migration Checklist to Follow

Before proceeding with the complex native tenant-to-tenant migration in M365, ensure the following:

• Have active Microsoft 365 subscriptions with licensing 
• Admin access for both tenant accounts (source and target)
• Exchange Online configured and validated 
• Reviewed identities, UPNs, SMTP addresses, and other 
• Determine domains to keep, move, and DNS timelines
• Assess mailbox size, permissions, status, and policies 
• Lower TTL value, plan rollback, and run pilot migrations 
• Mailbox migration and creating organizational relationships

Cross Tenant Migration Microsoft 365: Manual Route 

Microsoft offers native support for cross-tenant data transfers via Exchange Online. Organizations with Microsoft expertise and technical skills can follow this method after fulfilling the above prerequisites. Steps are:

1. In Exchange Online (Microsoft Entra Admin Center), start by preparing the target tenant. 
2. Create the Application Client ID and set the API Mailbox.Migration Permissions. 
3. Further, create a new client secret and grant permissions for your target tenant. 
4. Copy and secure the generated consent URL needed for the source tenant account. 
5. After that, configure a trust relationship between the source and target tenants to authenticate migration requests. 
6. Create new endpoints and build organizational relationships to move domain between Office 365 Tenants.
7. Register the application and grant necessary permissions. Create a CSV with source and target mailbox addresses and identifiers for mapping. 
8. Set your source tenant and create a new migration batch in the Microsoft 365 Admin Center. 
9. Map the source and tenant accounts with the CSV file and run the migration batch with PowerShell commands. 
10. Monitor the progress and wait until the migration completes successfully. In the end, remove endpoints and relationships. 

Note: Update the MX Records and check DKIM and DMARC settings post-migration.

This is a summed-up version of the manual method for the cross-tenant mailbox, OneDrive, or SharePoint migrations. Still, the method is too complex to understand and perform for non-technical users. Moreover, there are many other limitations attached to this method. 

Shortcomings of the Method

• Admin credentials and tech knowledge are mandatory. 
• Proper internet connectivity and permissions are required. 
• Too time-consuming and hectic with very large tenant migrations. 
• High chances and risk of losing the data due to human errors. 
• Improper configurations or a wrong step can halt the entire workflow. 
• Additional plans needed for OneDrive and SharePoint migrations. 

So, what’s the ideal solution to overcome these limitations and even handle mailbox throttling during migration without downtime or issues? It’s none other than a professional software solution, as explained in the upcoming section. 

Cross Tenant Migration Microsoft 365: Expert Route

SysInfo Microsoft 365 Tenant to Tenant Migration Software is a one-stop solution for hassle-free and secure migrations. It instantly connects the source and target tenants via Modern OAuth and Graph API and transfers all mailboxes, SharePoint, and OneDrive data without any difficulties. Additionally, it helps with custom and automated mapping and offers advanced filters for customized migration as desired by the individual, IT professional, or enterprise. Moreover, it preserves the structure and data fidelity, ensuring the business-critical data remains compliant and accessible as in the original tenant. 

Cross-Tenant Mailbox Migration Working Procedure 

1. Run the Office 365 Tenant to Tenant Migration Tool. Hit Copy Mailboxes.
   
   
2. Then, select the source tenant after opting for modern authentication mode and sign in. 
   
3. Further, pick the tenant user IDs and tap Continue to migrate emails.
   
4. Afterward, use Saved Credentials or Add New as desired, and complete authentication for the target tenant.
   
   
5. Later, verify the selected source mailboxes that you want to migrate and hit Continue to proceed.
   
6. Next, use the drop-down and map the source and target tenant accounts. Verify the mapping status. 
   
7. Finally, apply filters, pick the way to save the data in the target tenant, and tap Start Migration.
   
   

Later, you can check the migration progress in the Active Tasks window, and after completion, browse to All Reports. There, you can find a detailed report for the entire Microsoft 365 cross tenant mailbox migration. 

Conclusion 

Achieve a successful cross tenant migration Microsoft 365 by managing dependencies and choosing a reliable solution. Both native Microsoft PowerShell and Admin Center, and the SysInfo M365 Migration Tool work for a correct migration between the tenant accounts. It ensures all mailboxes, domains, identities, permissions, OneDrive content, and SharePoint sites are transferred securely. Ensure simplified migration of your data with pilot tests, throttling management, and comprehensive logs for guaranteed outcomes. 

Frequently Asked Questions

About The Author:

Simran Bhatia

Simran Bhatia is a technical content writer engaged in writing clear, concise, and SEO-optimized content. With a background in computer science and a passion for writing, I thrive to deliver complex technical content in simple layman terms.