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Hello Microsoft Support,
Tenant ID: <PII REMOVED>
We are experiencing a critical issue with our Azure AD tenant. All guest invitations are now failing with the following error from the Graph API:
Invitations are blocked for this directory due to suspicious activity. Please contact Microsoft support for help.
Context of Issue: I am the Global Administrator for this tenant. It's an external tenant, not our corporate tenant. While developing an external application, we were inviting external users as part of the development process, and started to receive a message that invitations were suspended due to suspicious activity. Some of the user accounts being tested were real, others were fake to test for pattern matching, and other error handling, as well as not wanting to spam legitimate email addresses.
Eventually, after several days of successful development, errors started happening:
"error" : {
"code" : "Forbidden", "message" : "Invitations are blocked for this directory due to suspicious activity. Please contact Microsoft support for help.",
"innerError" : {
``` "request-id" : "<PII REMOVED>",
"date" : "2026-03-13T03:45:49",
"client-request-id" : "<PII REMOVED>" }
}
**Impact:**
- We can no longer invite any new guests, which has halted our ability to test and develop
- This is impacting our deliverables and forcing a costly delay to the product
- In the future, we will be bulk uploading potentially 100's to 1000's of external users so these invitations must be allowed
**Request:**
- Please review and remove the "suspicious activity" block on our directory's invitation capability.
- Please confirm any guidelines or best practices to avoid hitting this block in the future.
Managing external identities to enable secure access for partners, customers, and other non-employees
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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):
Thank you for your patience.
We engaged with the Microsoft Data Protection team we have received the confirmation that the tenant has been unblocked now.
If you need any further assistance, please let us know.
Thank you for contacting Microsoft Q&A!