IP 40.107.8.108 Listed on SpamCop

Dear Francisco Javier Mateos Ugena,

Good day! Thank you for reaching out to the Microsoft Community. We appreciate your inquiry, and we are dedicated to assisting you promptly. Our team is actively reviewing your situation, and we will provide you with an update on the thread accordingly.

Your patience and understanding are valued, and we sincerely thank you for your time and cooperation.

Sincerely,

Libeamlak | Microsoft Community Moderator

Hello Francisco Javier Mateos Ugena,

Thank you for posting this case in Microsoft Community!

Based on your description:

EX703958

Title: Some users may be unable to send or receive email messages and receive a Non-Delivery Report (NDR)

User impact: Users may be unable to send or receive email messages and receive a NDR with a 550 or 554 error code.

More info: This issue only occurs if either the sender or user who is receiving the message is utilizing a specific third-party anti-spam service. Senders receive the NDR which states that the message has been rejected due to a 550 or 554 error code and that their host IP address is listed on the third-party anti-spam service. The error messages state "550 5.7.350 Remote server returned message detected as spam", "554 5.7.1 Service unavailable; Client host [xxx.xxx.xxx.xxx] blocked", or "‎550 5.7.1 This email was rejected because it violates our security policy."

Current status: We're continuing to work in conjunction with the third-party service to delist IP addresses which are blocked on the third-party's anti-spam service, In parallel, we're continuing to develop the anti-spam optimizations for long-term mitigation, which we'll provide a timeline for deployment to the affected environment when available. Scope of impact: This issue may affect any user's mail flow if the recipient is leveraging a specific third-party anti-spam service to filter email messages.

Next update by: Thursday, January 18, 2024 at 7:30 AM GMT+8

Users can view current information and updates on the Service's health dashboard at the link here https://portal.office.com/servicestatus.

In order for affected customers to easily identify the information here, this topic will be closed. You can click "I have the same question" in this topic or refer to SHD for up-to-date information. I'll also post back here once the issue is resolved in SHD.

Your understanding and patience will be appreciated.

Thank you!