We are getting S3150 for our IP when sending to Outlook/MSN, hotmail or msn.com

Question

Is is the proper procedure to delist from https://sender.office.com/?

Answer 1

Hi @Yvonne 

Thanks for reaching out to the Microsoft Q&A forum.   

To resolve the error code S3150 when sending messages to Outlook.com, please submit a support request through the following link: https://olcsupport.office.com/ 

The support team will be able to review your case and assist with the unblock process, as indicated in the troubleshooting documentation: Troubleshooting 

Please note that the unblock process can only be handled through a support request submitted via the link above. It cannot be completed through general forum platforms. 

I hope this helps you move forward. 

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Answer 2

If you are receiving an S3150 error when sending emails to Outlook, MSN, or Hotmail, it indicates that your IP address is likely blocked. To resolve this issue, you can use the Office 365 Anti-Spam IP Delist Portal at https://sender.office.com to request removal from the blocked senders list. This is the proper procedure for delisting your IP address.

Make sure to follow the instructions on the portal, using the email address that received the non-delivery report (NDR) and the specified IP address in the error message. After submitting your request, it may take some time for the changes to take effect.

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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
• Microsoft 365 services for external email senders