B2B guest invitations are blocked at tenant level. Both Bulk invite (CSV) and single manual invites fail with: "Invitations are blocked for this directory due to suspicious activity. Please contact Microsoft support for help."

Question

Issue:

B2B guest invitations are blocked at tenant level. Both Bulk invite (CSV) and single manual invites fail with:

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

Scope:

• Bulk invite: fails
• Manual single invite: fails
• Regular user creation in the tenant works (confirmed). Only invitations are blocked.
• We confirmed that the issue can be reproduced by multiple global administrators.
• We waited about two hours and tried again, but the problem did not improve.

Timeline:

Started around JST 2026/2/24 10:00AM. First 11 invites succeeded, then all invites started failing.

Constraint:

We were instructed to open a ticket in Azure portal, but our Azure support plan is Basic, so we cannot create a support request.

I can share Tenant ID / timestamps / correlation or request IDs via private message.

Request:

Could you advise how to get the tenant unblocked (review and remove the invitation block) and what exact telemetry/IDs are needed?

I referred to the following
https://learn.microsoft.com/en-us/answers/questions/4374289/invitations-are-blocked-for-this-directory-due-to
https://learn.microsoft.com/en-us/answers/questions/5784724/invitations-are-blocked-for-this-directory-due-to
https://learn.microsoft.com/en-my/answers/questions/5778488/invitations-are-blocked-for-this-directory-due-to
https://learn.microsoft.com/en-us/answers/questions/5783107/403-forbidden-invitations-are-blocked-for-this-dir

Answer 1

To resolve the issue of B2B guest invitations being blocked at the tenant level due to suspicious activity, you will need to take the following steps:

1. Review Security Settings: Check your tenant's security settings and ensure that there are no policies in place that might be causing the block. This includes reviewing any recent changes that may have been made to your B2B collaboration settings.
2. Contact Microsoft Support: Since your Azure support plan is Basic and does not allow for direct support requests, consider reaching out to Microsoft through other channels. You can use the Microsoft support forums or community support to seek assistance. Additionally, if you have access to any other Microsoft support resources (like a partner or a different support plan), utilize those.
3. Gather Telemetry Information: When contacting support, be prepared to provide the following information:
   • Tenant ID
   • Timestamps of the failed invitations
   • Any correlation or request IDs related to the failed invites
   • A detailed description of the issue, including the error message you received.
4. Wait for Resolution: After contacting support, it may take some time for them to review the situation and remove the block. Be patient and follow up if necessary.

Unfortunately, without a support ticket, it may be challenging to expedite the resolution. If the issue persists, consider upgrading your support plan for more direct assistance.

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References:

• Troubleshoot common issues with Microsoft Entra B2B collaboration
• Allow or block B2B collaboration with organizations