S3150 filtering.

Question

We are experiencing outbound delivery issues to Outlook.com / Hotmail.com recipients.

Our sending IP ([Moderator note: personal info removed]) is not listed on any public or Microsoft IP blocklists.

SPF, DKIM, and DMARC are correctly configured and passing.

Error received:

550 5.7.1 Unfortunately, messages from this sender were not sent.

The IP is associated with S3150 filtering.

This is a small business mail server (MailEnable), not used for bulk or marketing emails.

Volume is very low and emails are sent only to known recipients.

We request a review and removal of the sender-level restriction.

Answer 1

Please note that this is the Turkish (tr‑TR) forum. I kindly recommend posting your question in Turkish so that more community members can assist you effectively. If you prefer using English, you are welcome to post in the en‑US forum instead. I sincerely appreciate your understanding and cooperation.

Please note that Q&A forum is a public platform, and moderators will modify the question to hide personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.

Hi Ali ÖZKANLI

Thank you for reaching out via the Microsoft Q&A forum.

According to your description, I would like to share some information that I hope will help. Based on my research, there appear to be multiple factors that could affect this issue. Kindly refer to this article and ensure that your email aligns with Microsoft policies and guidelines: Troubleshooting. Should your email meet the required policies and guidelines, and you continue to face delivery problems not addressed there, please raise a support ticket through: New support request

Additionally, I hope you understand that as a Microsoft Q&A moderator, my role is to guide discussions and connect users with helpful resources. While I don’t have the right to access to individual account or your environment in order to help you further, but I still try my best to support you using the resources available. So, please take a look in these links above and follow them.

I hope this information is helpful.

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