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 11,825 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).

Your answer

Thanmayi Godithi 11,825 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).