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

Hao Xu 0 Reputation points
2026-03-23T10:30:25.0633333+00:00

we are using Graph API to create folders and files in our SharePoint and then share them with external users.
the issue is that when we use the https://graph.microsoft.com/v1.0/invitations API to add a external user to our tenant, the request is blocked with error message: Invitations are blocked for this directory due to suspicious activity. Please contact Microsoft support for help.'.

client_request_id='PII'

request_id='PII'

tenant id = 'PII'

how to resolve this and how to avoid this situation in the future?

Microsoft Security | Microsoft Entra | Microsoft Entra External ID

2 answers

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  1. Catherine Kyalo 3,180 Reputation points
    2026-04-21T15:29:18.4833333+00:00

    Your tenant is receiving the error "Invitations are blocked for this directory due to suspicious activity" when using the Microsoft Graph API (/v1.0/invitations) to invite external users. This typically occurs when Microsoft detects unusual invitation patterns from the tenant, such as a high volume of invitations in a short time or invitations to suspicious domains.

    Troubleshooting Steps

    1. Contact Microsoft Support — This block is applied by Microsoft's automated security systems. Open a support request through the Azure portal > Help + Support > New support request to have the block reviewed and lifted.
    2. Review your B2B collaboration settings — Go to Azure Portal > Microsoft Entra ID > External Identities > External collaboration settings and verify your invitation restrictions are configured correctly (allowed/blocked domains).
    3. Check for compromised credentials — Review sign-in logs (Microsoft Entra ID > Monitoring > Sign-in logs) for any suspicious activity that may have triggered the block.
    4. Throttle invitations — Once unblocked, implement rate limiting in your application to avoid triggering the protection again. Avoid bulk-inviting large numbers of external users in a short timeframe.
    5. Use batch invitations cautiously — If you need to invite many users, space out the invitations and ensure recipients are from legitimate, known domains.

    Reference Documentation

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  2. Thanmayi Godithi 11,905 Reputation points Microsoft External Staff Moderator
    2026-03-23T10:33:32.9033333+00:00

    Hi Hao Xu ,

    Thank you for reaching out to Microsoft Q&A.

    Based on the error message you received, it appears that invitations are blocked on your account due to suspicious activity.

    Our internal team has resolved this issue and your account is now unblocked.

    You can check if you were able to access your account.

    We hope you find this information useful. If you have any questions, please do not hesitate to contact us. We will be happy to help you.

    If you are satisfied with this answer, click "Accept Answer" and "Yes" to let us know if it was helpful. If you have any other questions, please do not hesitate to contact us.

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