Delivery problem to Outlook/Hotmail - IP 149.102.159.175 - Error S3150

Question

Hello,

I am the administrator of the mail server for onda15.com (IP: 149.102.159.175). We are experiencing permanent delivery failures when sending emails to Outlook/Hotmail recipients.

Error details: 550 5.7.1 Service unavailable; Client host [149.102.159.175] blocked using block list (S3150).

Troubleshooting already done:

We checked the "Delist Portal" and it says the IP is not blocked, yet emails are still being rejected.

Our server has valid SPF, DKIM, and DMARC records properly configured.

We have verified there is no outgoing spam from our server.

Could you please review the reputation of this IP and mitigate the block? Our server is used for legitimate business communications.

Thank you for your assistance.

Answer 1

Hello

Is this your DMARC record? If so, that is still problematic.