Entra ID B2B invitations blocked due to suspicious activity on new tenant (no direct support available)

Question

Entra ID B2B invitations blocked due to suspicious activity on new tenant (no direct support available)

Cristiano Quadrini 5

We have a Microsoft Entra ID tenant where ALL B2B invitations are blocked.

Error returned by the portal and Microsoft Graph:
"Invitations are blocked for this directory due to suspicious activity"

Context:

Only ~12 manual B2B invitations were sent
No scripts, no automation, no bulk operations
Invitation emails were not delivered
Even Global Administrators are blocked
The tenant has no ability to open direct support requests

We attempted to open a support case from another tenant with active support, but were instructed to request assistance for the affected tenant.
However, this tenant cannot open support tickets by design.

This appears to be a false-positive antifraud lock that commonly affects new Entra ID tenants.

Could Microsoft please review this tenant internally and remove the B2B invitation restriction?

Thanmayi Godithi 11,905 Reputation points Microsoft External Staff Moderator

2026-04-21T10:57:38.7233333+00:00

Cristiano Quadrini ,Thank you for reaching out to Microsoft Q&A.

As part of its security enhancements, Microsoft has anomaly detection systems in place to identify unusual activity, such as an unusually high number of invitations being sent from a tenant. If such anomalies are detected, the tenant may be temporarily blocked.

To unblock your tenant, please provide a business justification explaining the need for bulk invitations along with requested details via private message only (do not post publicly).
Annamária Rita Vágnerné Pocsaji 0 Reputation points

2026-10-08T06:47:43.67+00:00

Hello,

I am experiencing exactly the same issue with my Microsoft 365 Business Basic tenant.

After approximately 10 legitimate external invitations, all new B2B guest invitations were blocked with the following error:

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

I am an agricultural consultant in Hungary. I need to share separate OneDrive folders with approximately 50 agricultural clients, each having access only to their own folder.

I have already reported the issue through Microsoft 365 Service Health, but I have been unable to submit a direct support ticket.

Could a Microsoft moderator please help me get this restriction reviewed and removed? I can provide my tenant ID privately.

Thank you for your assistance.

1 answer

Your answer

Thanmayi Godithi 11,905 Reputation points Microsoft External Staff Moderator

2026-04-21T10:57:38.7233333+00:00

Cristiano Quadrini ,Thank you for reaching out to Microsoft Q&A.

As part of its security enhancements, Microsoft has anomaly detection systems in place to identify unusual activity, such as an unusually high number of invitations being sent from a tenant. If such anomalies are detected, the tenant may be temporarily blocked.

To unblock your tenant, please provide a business justification explaining the need for bulk invitations along with requested details via private message only (do not post publicly).
Annamária Rita Vágnerné Pocsaji 0 Reputation points

2026-10-08T06:47:43.67+00:00

Hello,

I am experiencing exactly the same issue with my Microsoft 365 Business Basic tenant.

After approximately 10 legitimate external invitations, all new B2B guest invitations were blocked with the following error:

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

I am an agricultural consultant in Hungary. I need to share separate OneDrive folders with approximately 50 agricultural clients, each having access only to their own folder.

I have already reported the issue through Microsoft 365 Service Health, but I have been unable to submit a direct support ticket.

Could a Microsoft moderator please help me get this restriction reviewed and removed? I can provide my tenant ID privately.

Thank you for your assistance.

Answer 1

Hello,

I am experiencing exactly the same issue with my Microsoft 365 Business Basic tenant.

After approximately 10 legitimate external invitations, all new B2B guest invitations were blocked with the following error:

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

I am an agricultural consultant in Hungary. I need to share separate OneDrive folders with approximately 50 agricultural clients, each having access only to their own folder.

I have already reported the issue through Microsoft 365 Service Health, but I have been unable to submit a direct support ticket.

Could a Microsoft moderator please help me get this restriction reviewed and removed? I can provide my tenant ID privately.

Thank you for your assistance.