550 5.7.708 low reputation IP block when sending via Graph API application permissions in new Microsoft 365 tenant - how to request IP exception?

Question

Hello,

In our new Microsoft 365 tenant, outbound emails via Microsoft Graph API (application permissions, client credentials flow) are blocked with error 550 5.7.708 Service unavailable. Access denied, traffic not accepted from this IP.

Manual sending from Outlook Web works fine, internal emails work, but external (e.g., Gmail) are rejected.

NDR example:

Remote server returned '550 5.7.708 Service unavailable. Access denied, traffic not accepted from this IP. For more information please go to http://go.microsoft.com/fwlink/?LinkId=526653 AS(7230) [PN2PR01MB8781.INDPRD01.PROD.OUTLOOK.COM 2026-01-10T18:36:33.655Z 08DE4FBF6F996242]'

Tenant ID: <my tenant ID>

This is a known issue for new/trial tenants with low reputation outbound IPs. Microsoft docs say to contact support for IP address exception until Exchange licenses are assigned.

Please help request IP exception / sending exclusion or escalate to engineer.

Thank you!

Answer 1

To address the issue of outbound emails being blocked with the error 550 5.7.708 in your new Microsoft 365 tenant, it is recommended to contact Microsoft support for an IP address exception. This situation often occurs with new or trial tenants that have low reputation outbound IPs. Microsoft documentation indicates that until Exchange licenses are assigned, you should reach out to support to request an IP exception or sending exclusion.

Additionally, ensure that your email sending practices align with best practices to avoid being flagged as low reputation in the future. This includes verifying your SPF records and ensuring that your sending IP address is static and properly configured.

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References:

• External senders - Use the delist portal to remove yourself from the blocked senders list and address 5.7.511 Access denied errors
• Fix issues with Microsoft 365 or Office 365 SMTP relay

Answer 2

Hi @Tarun Wadhwani 

Thank you for posting your question in the Microsoft Q&A forum. 

To resolve the issue, you’ll need to open a support ticket in the Microsoft 365 admin center and request an IP address exception to be applied to your tenant.

If you have an active Microsoft 365 subscription and hold the Global Admin role, you can submit a support request directly through the Microsoft 365 admin center. Once submitted, a Microsoft Support agent will reach out to you. 

For further instructions, you can follow this guide: Get support - Microsoft 365 admin | Microsoft Learn.  

We appreciate your understanding and patience in this matter. As forum moderators, we don’t have access to internal databases or the ability to escalate cases directly to Microsoft’s internal teams. Therefore, please kindly contact the Microsoft Support team for the most efficient help.  

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