Delivery Failure to Outlook/Live/Hotmail Accounts
If your mail server's IP is added to a blacklist, you may receive delivery failures similar to the following when sending to Outlook/Live/Hotmail mailboxes:
Subject: Undeliverable: Test Message
DB5EUR01FT042.mail.protection.outlook.com rejected your message to the following e-mail addresses:
DB5EUR01FT042.mail.protection.outlook.com gave this error:
Unfortunately, messages from [a.b.c.d] weren't sent. Please contact your Internet service provider since part of their network is on our block list (AS3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [DB5EUR01FT042.eop-EUR01.prod.protection.outlook.com]
Your message wasn't delivered due to a permission or security issue. It may have been rejected by a moderator, the address may only accept e-mail from certain senders, or another restriction may be preventing delivery.