Persistent Email Delivery Failure - Sender's Server IP Blocked by Microsoft Block List

Help: Unable to Receive Emails from Specific Sender Due to Sender IP Block (Error Code S3150)

I am a long-term Hotmail user from Hong Kong. I have been experiencing a critical issue for several weeks: I consistently fail to receive emails from an important client.

I have repeatedly checked my account settings, including the spam filter, safe sender list, and followed all recommendations in the official help documents. Unfortunately, the problem persists. Attached is the full Non-Delivery Report (NDR)/bounce-back message obtained from my client. The report clearly indicates that the Microsoft servers handling my Hotmail account rejected the message from IP address [153.128.190.153] because it is "on our block list (S3150)."

The key error information is as follows:

· Status Code: 5.7.1

· Diagnostic Code: 550 5.7.1 ... part of their network is on our block list (S3150).

· Reference Link: http://mail.live.com/mail/troubleshooting.aspx#errors

As this issue severely impacts my normal business communication with this client, and I cannot directly contact their Japanese email service provider, I kindly request your team to:

1. Investigate the block status associated with the sender's IP 153.128.190.153 (domain giga.ocn.ne.jp).
2. Provide any possible solutions or assistance from the recipient's (my account ******@hotmail.com) side.

Thank you for your time and assistance. I look forward to your reply.