anyone on from hotmail.com, msn.com, live.com smtp?

[joe at breathe-underwater.com (Joseph Jenkins)]

We are getting this messages when sending emails from our domain. We've
submitted tickets, but haven't received a response yet. Anyone have any
insights?

550 5.7.1 Unfortunately, messages from [1.1.1.1] 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. [
AM5EUR03FT014.eop-EUR03.prod.protection.outlook.com]

It's our own address and everything on the Microsoft site says we are clean
with no issues.
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