SMTP error from remote mail server after pipelined sending data block:
550 5.7.1 Unfortunately, messages from [220.127.116.11] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3140). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [BN8NAM12FT041.eop-nam12.prod.protection.outlook.com 2023-02-27T17:36:10.004Z 08DB1839B69382CA]
3 months ago
I can get this specific block reported, but sometimes, on shared hosting where many customers use the same email servers, they get detected as contributing to spam and unnecessarily get blacklisted by a few recipient email servers and RBLs. We do have a system in place that monitors our mailout server IPs for their reputation at RBLs that sends out reports periodically. Our Network Operations team rotates the blocked IPs automatically and that should resolve any blocks our servers may have, given time. We do recommend trying to resend the bounced emails.
Additionally, we have already informed our engineering team regarding this issue and our engineers are working towards a fix on increasing the reputation. I'm afraid we do not have an ETA on this. We appreciate your patience while we resolve this issue.