Request to remove tenant-level B2B invitation security block – NerveIT

Question

Request to remove tenant-level B2B invitation security block – NerveIT

Nicolás Javkin 0

Hello Microsoft Entra Support Team,

We are experiencing a tenant-level B2B invitation restriction in our Microsoft 365 Business Premium environment.

The exact error is:

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

We have already verified:

External collaboration and guest invitations are enabled.

Inbound and outbound B2B collaboration are allowed.

There are no general domain restrictions.

SharePoint and OneDrive external sharing are enabled.

Direct guest invitations from Microsoft Entra also fail when performed by a Global Administrator.

Our business requires secure, authenticated file sharing with external users across different Microsoft 365 tenants.

We have found identical cases where Microsoft's internal Entra team successfully removed the tenant-level invitation restriction.

We request:

Verification of any automated security or anti-abuse restriction affecting our tenant.

Escalation to the Microsoft Entra B2B / External Identities engineering team.

Review and removal of the invitation block, if confirmed.

Confirmation once external B2B invitations have been restored.

We can provide the Tenant ID, Global Administrator email, failure timestamp, and correlation ID through a private support channel.

Please advise how to proceed with the tenant unblock request.

Thank you.

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2 answers

Your answer

Answer 1

Hi @Nicolás Javkin

Based on the error message, your tenant's ability to send guest invitations appears to have been restricted by Microsoft's security protections. This may require Microsoft Support to review the restriction.

If you have a Microsoft 365 Global Administrator account, you can create a support request by following these steps:

Sign in to the Microsoft 365 admin center using your Microsoft 365 Business administrator account.
Select the Help & support (headset) icon.
If Support Assistant is enabled, turn it off.
Type contact support in the search box.
Select Contact support, then choose Phone or Email to submit your request.

Once you've submitted the request, Microsoft Support will contact you using the contact method you selected.

For further instructions, you can follow this guide: Get support - Microsoft 365 admin | Microsoft Learn.

If you are not a Global Administrator, please contact your Microsoft 365 tenant administrator and ask them to create the support request on behalf of your organization. If you are unsure who your administrator is, you can refer to this guide: How do I find my Microsoft 365 admin? - Microsoft Support.

Please note that this is a user-to-user support forum, not an official Microsoft Support channel. Community members do not have access to Microsoft's internal systems or the ability to directly escalate cases to the appropriate Microsoft support team.

Answer 2

This restriction requires a Microsoft support case and internal review; it cannot be removed through the tenant’s External Identities, cross-tenant access, SharePoint, or OneDrive settings.

Submit the unblock request

Because this is a Microsoft 365 Business Premium workforce tenant:

Sign in to the Microsoft 365 admin center using an administrator account.
Select Help & support at the lower-right.
Enter the exact error:

Invitations are blocked for this directory due to suspicious activity. Please contact Microsoft support for help.
If the suggested results do not resolve it, select Contact Support (headset icon).
Choose phone or email, confirm the contact details, and submit the request. Microsoft documents this as the online technical-support route for Microsoft 365 business administrators.^1^

If all subscriptions were purchased through a Microsoft partner rather than directly from Microsoft, open the case through that partner; Microsoft’s Business support guidance directs partner-purchased subscriptions to the partner support channel.^1^

Alternatively, an account with at least the Service Support Administrator role can open a request from:

Microsoft Entra admin center → Diagnose and solve problems → Self-Service Support → Create a support request

Continue past Recommended solution, complete Additional details, and select Create. Microsoft recommends including when the issue began, reproduction steps, and relevant logs or diagnostic output.^2^

Information to put in the case

Use a single-issue case with a title such as:

Microsoft Entra B2B tenant invitation block — suspicious activity — internal unblock requested

Include:

Tenant ID.
Tenant type: Microsoft Entra workforce tenant.
Subscription: Microsoft 365 Business Premium.
Exact error text.
UTC timestamp of a recent failed invitation.
Correlation ID and request ID, if shown.
Inviting administrator’s user principal name.
One example invitee domain, without posting personal information publicly.
Invitation method: Entra admin center, Microsoft Graph, SharePoint, or other affected entry points.
Confirmation that the failure occurs for multiple external domains and for a Global Administrator.
Business impact and expected invitation volume.
Screenshot or exported diagnostic details.
Explicit routing request:

Please verify whether an automated security or anti-abuse restriction is applied to this tenant’s B2B invitation capability. If confirmed, escalate the case to the Microsoft Entra B2B/External Identities team for review and removal of the tenant-level invitation block. Please confirm when invitations have been restored.

Provide tenant identifiers, administrator details, timestamps, and correlation IDs only through the private support case, not in a public Q&A post.

Why configuration changes are not the next step

The policy-related B2B failures documented by Microsoft use different messages—for example, an invitation blocked by cross-tenant access settings. Microsoft separately documents permission-based failures as notifications that the user lacks permission to invite.^3^

Your exact “suspicious activity” message, tenant-wide impact, and failure from Entra as a Global Administrator match published cases where Microsoft collaborated with an internal team and then unblocked the tenant.^4^ A separate case with the same error reports the same internal-unblock outcome.^5^

Since external collaboration, cross-tenant access, domain restrictions, and SharePoint/OneDrive sharing have already been checked, changing those settings again would not address the indicated directory-level restriction.

After Microsoft confirms the unblock

Send one test invitation from Entra ID → Users → New user → Invite external user.
Confirm that the guest object is created.
Complete redemption with a controlled external test account.
Validate access to the intended SharePoint or OneDrive resource.
Update the support case with the result before allowing it to close.

Avoid immediately resuming a large bulk invitation run. Ask the assigned engineer whether any rate, batching, or onboarding guidance applies to the tenant before restarting high-volume invitations; the available documentation does not specify a self-service threshold that guarantees avoidance of this security restriction.

References