Simplifying Cross-Tenant Collaboration in Microsoft 365

As organisations grow and acquire other companies, managing multiple Microsoft 365 environments can quickly become a challenge. Users are often required to sign in to different tenants to access data, send emails, collaborate on Teams, or work on SharePoint. This friction can impact productivity and user experience.

Fortunately, Microsoft Azure Active Directory (Azure AD) offers two powerful solutions for simplifying collaboration while maintaining the independence of multiple tenants: Azure AD B2B Collaboration and Azure AD Cross-Tenant Synchronisation. Here, we’ll dive deep into how these solutions work, compare their features, and provide guidance on which might be the best fit for your organisation.

Understanding Azure AD B2B Collaboration

Azure AD B2B Collaboration enables you to invite users from another tenant (or external identity provider) as guest users into your environment. These users retain their accounts in their home directory but gain access to resources in the host tenant.

Key Features:

Teams Integration: Guests can join Teams meetings, participate in chats, and collaborate in shared Teams channels.
SharePoint Access: Specific SharePoint sites or libraries can be shared with guest users.
Identity Management: Guests authenticate using their home directory, while their identity is federated into the host tenant.
Conditional Access: Security policies such as multi-factor authentication (MFA) and access restrictions can be enforced for guests.

How It Works:

External users are invited as guests to your tenant.
Administrators grant access to specific Teams channels, SharePoint sites, or other resources.
Guest users authenticate with their home directory credentials but are validated in the host tenant.

Pros:

Ease of Setup: Quick and simple to invite guests.
Seamless Teams Collaboration: Ideal for ad-hoc collaboration in Teams.
Granular Access Control: Only specific resources are shared, maintaining tenant separation.
Cost-Effective: No additional licensing is required for guest access.

Cons:

Limited User Experience: Guests must manually switch tenants in Teams to collaborate fully.
Manual Management: Administrators must invite and manage guest users manually.
Restricted Integration: Guests cannot act as full members of the tenant.

Understanding Azure AD Cross-Tenant Synchronization

Azure AD Cross-Tenant Synchronisation automates the synchronisation of users across tenants. It creates guest users in a target tenant based on policies, making it ideal for large-scale or ongoing collaboration.

Key Features:

Automated Guest Creation: Users from one tenant are automatically added as guests in another tenant.
Ongoing Synchronisation: User updates (e.g., name changes) are reflected in the target tenant.
Teams Integration: Synchronised users can access shared Teams channels and meetings without tenant switching.
SharePoint Access: Preconfigured policies allow synchronised users to seamlessly access SharePoint resources.

How It Works:

Administrators configure trust relationships between tenants in Azure AD.
Synchronisation policies define which users or groups are synchronised.
Users from the source tenant appear as guests in the target tenant, with access managed via groups or Conditional Access policies.

Pros:

Automation: Eliminates the need for manual user invitations.
Scalability: Handles large-scale user synchronisation efficiently.
Customisability: Policies allow fine-grained control over which users are synchronised.
Seamless User Experience: Users access shared resources without manually switching tenants.

Cons:

Complex Setup: Requires more configuration than B2B Collaboration.
Licensing Costs: Requires Azure AD Premium P1 or P2 for both tenants.
Azure AD Dependency: Synchronisation is limited to Azure AD accounts.

Comparison: Azure AD B2B Collaboration vs Cross-Tenant Synchronization

Feature/Criteria	Azure AD B2B Collaboration	Azure AD Cross-Tenant Synchronisation
Setup Complexity	Low: Simple guest invitation process	High: Requires Azure AD trust and synchronisation setup
Automation	Manual: Users must be invited individually or via group	Automated: Synchronises users based on policies
Teams Sharing	Supported but requires tenant switching	Seamless for users added as guests
SharePoint Access	Granular, but manual sharing per resource/site	Seamless: Access can be pre-configured via policies
User Management	Manual: Admins must update guest lists	Automatic: User updates synced between tenants
Licensing Requirements	No additional licensing required	Requires Azure AD Premium P1 or P2
End-User Experience	Guests must switch tenants	Transparent: Synchronisation is seamless for end users
Resource Scope	Specific resources only	Can cover broader access across the environment
Scalability	Suitable for small-scale collaboration	Ideal for large-scale or ongoing collaboration

Recommendations Based on Common Scenarios

For Teams Sharing:

If users need seamless Teams collaboration for meetings and chats across tenants:

Short-Term: Use Azure AD B2B Collaboration for lightweight collaboration.
Long-Term: Use Cross-Tenant Synchronisation for users requiring frequent interaction, as it eliminates tenant switching.

For SharePoint Access:

Granular Access: Use Azure AD B2B Collaboration to share specific SharePoint sites or document libraries.
Broad Access: Use Cross-Tenant Synchronizstion to automate access and provide a seamless experience for users needing regular access to shared resources.

Combined Strategy for Maximum Flexibility

To address both short-term needs and long-term goals, consider combining both approaches:

Azure AD B2B Collaboration: Use for ad-hoc or project-based external collaboration where tenant switching is acceptable.
Azure AD Cross-Tenant Synchronisation: Use for ongoing collaboration with frequent interactions, ensuring a seamless user experience.

Conclusion

Managing multiple Microsoft 365 environments doesn’t have to be a pain point. By leveraging Azure AD B2B Collaboration and Cross-Tenant Synchronisation strategically, you can simplify collaboration, enhance productivity, and maintain tenant independence.

Whether your goal is to streamline Teams sharing, enable seamless SharePoint access, or automate user management, these tools offer powerful solutions to meet your needs. If you need help implementing these technologies or deciding which is the best fit for your organisation, feel free to reach out to us at Optimus Systems!

Strategy

Cybersecurity

Infrastructure

Support

Insights

FYiT

Strategy

Cybersecurity

Infrastructure

Support

Insights

Simplifying Cross-Tenant Collaboration in Microsoft 365

Why an MSP is Better than an Independent IT Provider for Your Business

Top Conditional Access Policies Every SME Should Know

Copilots for Everything!

FYiT Series

Key Concerns for Business Owners Rolling Out AI (Like CoPilot)

When your sensitive data surfaces online, you need to know first

Paranoia can be your best asset—if it’s Zero Trust

Protecting Business Data in the Palm of Your Hand