Microsoft Entra B2B Guest Invitations Blocked Due to Suspicious Activity – Request to Unblock Tenant

The “invitations are blocked for this directory due to suspicious activity” restriction cannot be removed through Microsoft Entra roles or collaboration settings; open a Microsoft 365 support request for a backend review and tenant unblock. Similar cases with the same error were resolved only after the Microsoft team removed the directory-level restriction.^1^

Open the support request

If the Microsoft 365 Business Basic subscription was purchased directly from Microsoft:

1. Sign in to the Microsoft 365 admin center using the Global Administrator account.
2. Select Help & support at the lower-right.
3. Enter:
   Microsoft Entra B2B invitations blocked for directory due to suspicious activity
4. If the suggested results do not resolve it, select Contact Support (headset icon).
5. Choose phone or email, confirm the contact information, and submit the request.^2^

If all subscriptions were purchased through a Microsoft partner or reseller, contact that partner instead; the official support procedure directs partner-purchased subscriptions through the partner.^2^

Information to include

Use wording similar to:

All Microsoft Entra B2B guest invitations fail with: “Invitations are blocked for this directory due to suspicious activity.”

The failure affects every new external invitation. External collaboration and domain settings permit invitations, existing guests remain present, and attempts are performed by a Global Administrator. Please check for a service-side restriction on the directory and escalate the case for backend security/abuse review and removal of the B2B invitation block.

Business purpose: SharePoint collaboration with legitimate external users.
Business impact: New external collaborators cannot be onboarded.

Also provide securely within the support case:

• Tenant ID and primary tenant domain
• Exact error text and a screenshot
• UTC date and time of a recent failed invitation
• Affected invitation method, such as SharePoint or Entra admin center
• Approximate number and timing of successful and failed invitations
• Whether every external domain is affected
• Business justification for the invitations
• Support contact details

Do not post the Tenant ID or administrator details in the public Q&A thread; provide them only through the authenticated support case or an authorized private support exchange.

What to expect

Support must review the directory-level restriction and determine whether it can be removed. Accepted cases reporting the same error confirm that an internal team performed the unblock; it was not cleared by changing tenant configuration.^3^

After Support confirms removal:

1. Send one test invitation from Microsoft Entra admin center → Entra ID → Users → New user → Invite external user.
2. Confirm that the guest object is created and the invitation is sent.
3. Resume invitations gradually rather than immediately submitting a large batch.

There is no documented threshold in the supplied guidance showing that 13 invitations trigger this restriction, so that sequence should be reported as diagnostic context rather than treated as the established cause.

References

1. Unable to send B2B guest invitations from Microsoft Entra - Microsoft Q&A
2. Get support for Microsoft 365 for business
3. Invitations are blocked for this directory due to suspicious activity. Please contact Microsoft support for help - Microsoft Q&A