Shared Mailboxes Migration from Tenant to Tenant Office 365

Migrating user mailboxes in a merger, acquisition, or divestiture is challenging enough, but Shared Mailboxes usually bring their own complexities. These mailboxes are the critical hubs of team communications, customer service, and departmental queries, such as info@ or support@, containing essential collaborative history and intricate permission sets that need to be preserved.

A simple oversight while handling Shared Mailboxes during the transfer between one Microsoft 365 tenant and another will result in disrupted workflows, communications, and security gaps.

This blog post provides the best methods for smooth, secure, and successful Shared Mailboxes migration from tenant to tenant Office 365 (or M365).

Why Shared Mailboxes Are Important to Migrate Accurately

Shared mailboxes allow teams to communicate and collaborate without the requirement for individual licensing. Departments like sales, HR, and support rely on them daily. Mishandling shared mailboxes during tenant-to-tenant migrations can lead to:

• Lost historical communication
• Broken folder structures
• Missing Permissions and Access Issues
• Disrupted workflows and email downtime

Therefore, enterprises should follow best practices and select the right migration tool to ensure all shared mailbox information, along with permissions and configurations, migrates securely to the new tenant.

Common Challenges with Shared Mailbox Migrations

Enterprises usually face a number of challenges when trying to move shared mailboxes between Microsoft 365 tenants:

• Complex Permissions: Shared mailboxes usually have multiple owners and delegates that require accurate mapping.
• Large data volumes: The departmental mailboxes can store years of emails and attachments, which makes their migrations time-consuming in nature.
• Downtime Risks: Even a few hours of mailbox inaccessibility can disrupt internal communication.
• Security and Compliance: Data loss or unauthorized access leads to compliance violations such as GDPR and SOC 2 Type 2, among others.

We at CloudFuze help enterprises overcome these hurdles by managing every stage of migration with high precision.

At CloudFuze, we bypass this complexity entirely.

How to Migrate Shared Mailboxes from Tenant to Tenant

Mainly, there are two approaches: manual migration and third-party migration tool.

Method 1: Manual Shared Mailbox Migration (PST Export/Import)

In Microsoft 365, shared mailbox migration can be done manually by exporting the mailbox data from a source tenant to a target tenant using Outlook or PowerShell.

Steps Involved:

• Temporarily convert the Shared Mailbox to a User Mailbox in the source tenant.
• Assign a License to the mailbox for export access.
• Export Data Using Outlook to a PST File
• Create a new shared mailbox in the target tenant.
• Import the PST file into the new mailbox through either Outlook or PowerShell.
• Manually reallocate Permissions on the source tenant for each person who was granted access.
• Convert the User Mailbox back to a Shared Mailbox once the data is fully imported.

Limitations of the Manual Method:

• Time-consuming for multiple shared mailboxes
• High risk of missing permissions or data
• Requires manual mapping and validation
• No built-in real-time monitoring
• Possible downtime for users during migration

This method will work for small organizations or one-time migrations, but it is not scalable for large enterprises.

Method 2: Migrating a Shared Mailbox using CloudFuze

Enterprises looking for a faster, error-free, and secure migration process use CloudFuze Migrate. Our tool preserves metadata, permissions, and folder structure accurately.

How CloudFuze Simplifies Shared Mailbox Migration

• Automatically retains all mailbox permissions
• Enables zero-downtime mailbox access
• Preserves 100% metadata and folder structure
• Handles any size with scalable API support
• Transfers calendars, contacts, and attachments accurately
• Mailbox mapping by importing via CSV

Key Metadata CloudFuze Preserves

CloudFuze’s 3-Phase Shared Mailbox Migration Framework

Phase 1: Planning and Pre-Staging with Precision

• Inventory and audit: Do an inventory of all Shared Mailboxes, their sizes, and their delegates.
• Target Provisioning: Ensure proper and accurate user access within the target tenant.
• Pre-Stage Migration: Prior to the final cutover, transfer most of the historical data in order to eliminate downtime.

Phase 2: Faster Data Transfer and Attribute Preservation

• Dedicated Batches: This allows for the optimization of migration batches for shared mailboxes.
• Data Fidelity: Ensure that all items, e-mails, calendars, and contacts migrate accurately.
• Attribute Preservation: By default, keep mailbox visibility and configuration settings.

Phase 3: Validation and Seamless Go-Live

• Permission Check: Checks that access levels remain the same after migration.
• Final Delta Sync: Before go-live, it captures all the incremental changes.
• User Readiness: Provide users with instructions for DNS updates and post-migration configurations.

Shared Mailboxes Migration Tenant to Tenant Office 365: Before and After

The screenshots above illustrate how our tool successfully migrates shared mailboxes from one Microsoft 365 tenant to another. It maintains structure, permissions, and data integrity.

• Before Migration (Left):

The user alex@gajha.com belongs to the source tenant. You can see multiple shared mailboxes (like filefuze, TNG, ISGR) associated with this tenant in Outlook. All emails, attachments, and folders reside under the source tenant.

• After Migration (Right):

After migration, the same shared mailboxes have been successfully replicated in the destination tenant (alex@filefuze.co). Our tool migrated all mailbox data, including messages, attachments, contacts, and calendar items. It retains permission settings such as Send As, Send on Behalf, and Full Access.

Our tool:

• Preserves mailbox hierarchy and permissions
• Delivers flawless continuity for Outlook users across tenants

Post-Migration Best Practices

After successful migration:

• Verify that all shared mailboxes are accessible to the intended users.
• Check send-as and calendar permissions.
• Safely decommission old mailboxes after verification.
• Inform the users about the new tenant’s mailbox structure and policies.
• Retain reports on migration for auditing and compliance.

Experience Seamless Shared Mailbox Migration

Your organization may plan a tenant-to-tenant migration in Office 365, where you do not need to use manual PowerShell scripts or risk data loss.
What you can achieve with CloudFuze Migrate:

• 100% data accuracy
• Zero Downtime
• Automated permission mapping
• Comprehensive reporting and compliance tracking

Schedule a free demo with CloudFuze’s migration experts today and see how shared mailboxes migrate across from one M365 tenant to another securely, safely, and with ease.

Frequently Asked Questions

1. Can shared mailboxes be migrated without first converting them into user mailboxes?

Yes, shared mailboxes can be directly migrated using CloudFuze without converting them to user mailboxes. In usual methods, they need to be converted manually.

2. Do I need licenses for shared mailboxes during the migration?

Shared mailboxes do not require licenses in the target tenant; however, temporary licenses may be required for manual exports in the source tenant.

3. How long does a shared mailbox migration take?

Migration time depends on the volume of data and the number of mailboxes. Migration using our tool is generally up to 10X faster compared to manual means or any other third-party tools.

4. Which permissions are preserved upon migration?

CloudFuze maintains Full Access, Send As, and folder level permissions to ensure the exact same access in the target tenant.

5. How do I monitor the migration process?

CloudFuze offers a real-time monitoring dashboard, which is readily available within CloudFuze Migrate and empowers IT admins to monitor status, performance, and completion.