iCloud Servers in Hotmail Blocklist - No Idea Who to Contact

Sending emails to hotmail.com addresses is returning as undeliverable with this message:

   hotmail-com.olc.protection.outlook.com[52.101.9.25] said: 550 5.7.1
   Unfortunately, messages from [57.103.64.177] weren't sent. Please contact
   your Internet service provider since part of their network is on our block
   list (S3150). You can also refer your provider to
   http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol
   Filter Agent][AGT=PFA][MxId=11BBBE5FED525DAE]
   [BL6PEPF00022570.namprd02.prod.outlook.com 2025-08-20T19:23:52.489http://mail.live.com/mail/troubleshooting.aspx#errors.

57.103.64.177 resolves to p-west1-cluster2-host1-snip4-6.eps.apple.com so this is up to Apple to sort out why they're on the block list. Unfortunately, there is no clear path to actually contacting someone about this. Any help would be appreciated.

Posted on Aug 20, 2025 12:34 PM