Invitations blocked due to suspicious activity in directory.

Question

Dear Microsoft Support,

We are currently experiencing a critical issue with our Microsoft Entra ID tenant, where we are unable to send B2B guest invitations via Bulk Invite, or even through the manual invitation option on the Entra portal.

Recently, we attempted to invite over 5,000 guest users from an external tenant using the Bulk Invite feature. Only 300 +- users were actually added. Subsequent attempts and manual invitations have failed, returning the error: “Invitations are blocked due to suspicious activity.”

There has been no abuse or suspicious behavior on our part. The issue appears to stem from the high volume of invitations being sent from our single available tenant, which is currently our only option.

This situation is urgent, as we are in the middle of critical migrations that depend on timely guest access via Entra. Furthermore, we plan to invite significantly more users in the coming weeks, and this blockage could severely impact our timelines.

We kindly request your assistance in reviewing and unblocking the guest invitation functionality for our directory as soon as possible.

Thank you for your support and understanding.

Answer 1

Hi Edwin Butler

This issue occurred because the tenant was less than or equal to 30 days old and had performed more than 500 email invitations.

As you performed a bulk invitation of 5,000 users from an external tenant to your tenant, you encountered this limitation. Thank you for confirming that the issue has been resolved by Microsoft Support. You should now be able to invite users in bulk without any issues.

Hope this helps. Do let us know if you any further queries.

Please remember to "Accept Answer" if answer helped you. This will help us as well as others in the community who might be researching similar questions.

Answer 2

Hello Edwin Butler,

As part of security enhancements, we have anomaly detections which checks if unusual invites are occurring from any tenants and based on that anomaly detections the tenant was blocked. Paid customers which tenant was created within 30 days can be blocked by bulk invitation >= 500 in 24 hour.

I recommend that you submit a support ticket to Microsoft Support and provide details of your tenant to help the support team unblock your tenant. Make sure to include some type of business reason from you for the requirement for bulk invitations. Make sure to provide the tenant ID and the timeframe of the error.

Hope this helps. Do let us know if you any further queries.

Please remember to "Accept Answer" if answer helped you. This will help us as well as others in the community who might be researching similar questions.

Best regards,