Invitations are blocked for this directory due to suspicious activity. Please contact Microsoft support for help

Hi @Yahya Aliyev

Based on the information provided, the message indicates that guest invitations from the tenant are currently being blocked at the Microsoft Entra B2B level. When this condition occurs, attempts to share files or folders with external users through OneDrive or SharePoint may fail with the error you described. 

Since the message explicitly states that invitations are blocked for the directory due to suspicious activity, this is something that needs to be reviewed by Microsoft Support so the best next step would be to ask your Global Admin (IT Admin) to raise a support ticket through the Microsoft 365 Admin Center for deeper investigation.   

A technical support engineer can perform a remote session to investigate the situation, verify the backend configurations, and run any necessary synchronization tools to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis.       

Here’s what your Microsoft 365 Global Admin (IT Admin) should do next:      

• Submit a Service Request: The Global Admin should create a service request with Microsoft support to get advanced technical assistance and diagnostics. For detailed instructions on how to get support, please refer to Get support - Microsoft 365 admin.        
• Find Your Microsoft 365 Admin: If you’re unsure who the Global Admin is within your organization, you can find guidance on locating them here: How do I find my Microsoft 365 admin? - Microsoft Support.    
• If your subscription is managed through a Microsoft partner or reseller, they can also assist with opening a support request and liaising with Microsoft on your behalf.     

Note: If you’re an end-user, please coordinate with your Office 365 Global Administrator to handle these steps.    

I apologize for redirecting you the related team support, as the moderators in this community don’t have access to the detailed system needed to troubleshoot this effectively due to privacy and security constraints. But Microsoft’s support team has elevated permissions and access to backend systems that we, as community moderators, do not. This ensures your issue is handled with the right tools and expertise and helps you get a faster resolution.      

Hopefully they will be able to help with your issue and if you have any other questions or need further assistance, feel free to ask.   

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread. 

The error indicates that Microsoft Entra B2B invitations from the tenant have been blocked due to suspicious activity. This is enforced at the directory level and prevents sending new guest invitations, including for SharePoint Online and OneDrive sharing.

Because the block is at the Entra B2B layer, it cannot be resolved only by changing SharePoint/OneDrive settings. The tenant administrator must:

1. Verify B2B/external collaboration configuration
   • In the Microsoft Entra admin center, review:
     • External collaboration settings under Entra ID > External Identities to confirm that guest invitations are allowed and that the contractor’s domain is not blocked.
     • Cross-tenant access settings to ensure B2B collaboration with the contractor’s organization is not denied.
   • These settings control whether users can invite and authenticate external guests and are checked at invitation time.
2. Check for domain allow/block policies
   • Under External collaboration settings, confirm whether an allowlist or blocklist is configured for B2B domains and that the contractor’s domain is not inadvertently blocked. Remember that only one allowlist or blocklist policy can exist per organization and that it is enforced at invitation time.
3. Engage Microsoft support to remove the suspicious-activity block
   • The specific message “Invitations are blocked for this directory due to suspicious activity. Please contact Microsoft support for help.” indicates a tenant-level protection that must be cleared by Microsoft.
   • A tenant administrator (preferably with Global Administrator or appropriate support-contact role) needs to open a support ticket with Microsoft. The Data Protection/support team can review the suspicious-activity flag on the directory and restore the ability to send B2B invitations.
4. After Microsoft clears the block
   • Retest sharing from OneDrive/SharePoint by inviting the contractor again.
   • If invitations still fail with cross-tenant or guest restriction errors, re-check:
     • Cross-tenant access settings for the contractor’s tenant.
     • External collaboration allow/block lists.
     • Any SharePoint/OneDrive-specific external sharing restrictions.

Until Microsoft support removes the suspicious-activity block on the directory, B2B invitations (including OneDrive sharing to new external guests) will continue to fail with this error.

References:

• Error: ResponseStatusNotOK when sharing a SharePoint or OneDrive site
• Troubleshoot common issues with Microsoft Entra B2B collaboration
• Overview: B2B collaboration with external guests for your workforce
• Allow or block B2B collaboration with organizations