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

Question

I have successfully invited 8 guest users and am now blocked from adding more due to suspicious activity. MS case ID is not understanding the issue. It is not a user problem, my tenant is blocked. The other question is around sensitivity as 8 guest users is not what what I would call suspicious enough to trigger a flag like this.

Please resolve.

Answer 1

The message indicates that guest invitations are being blocked at the tenant level due to Microsoft detecting suspicious activity. This is enforced by Microsoft’s backend protection systems and cannot be cleared by configuration changes in Microsoft Entra ID alone.

Because the block is on the directory itself, resolution requires direct Microsoft support intervention. The correct path is:

1. Open or update a support request from the affected tenant’s admin account in the Microsoft 365 or Azure/Microsoft Entra admin portal.
2. Clearly state that:
   • Guest invitations are blocked for the entire directory due to suspicious activity.
   • This is not a per-user or policy misconfiguration issue (cross-tenant access, external collaboration, or SharePoint/OneDrive settings), but a service-level protection block.
3. Ask support to:
   • Escalate the case to the appropriate service team that handles tenant-level protection/abuse and Acceptable Use Policy enforcement.
   • Review and remove the block if the tenant is compliant with the Microsoft Online Services Acceptable Use Policy.

If Microsoft believes the tenant is associated with activity that violates the Acceptable Use Policy, the tenant will remain restricted until the investigation is completed and the block is lifted. Admins must work through the support case; there is no self-service override.

If guest invitations are also failing specifically in SharePoint or OneDrive, and users see “This invitation is blocked by cross-tenant access settings” or “Guest invitations not allowed for your company,” verify that B2B collaboration and external sharing settings are configured as intended, but this will not remove a tenant-level suspicious-activity block.

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References:

• Error "This page has been blocked as it violates the Acceptable Use Policy"
• Error: ResponseStatusNotOK when sharing a SharePoint or OneDrive site
• Troubleshoot common issues with Microsoft Entra B2B collaboration
• What is Microsoft Entra B2B collaboration?