Our users cannot email any hotmail.com, live.com, msn.com, or outlook.com domains.
Here's the bounceback we're receiving:
com gave this error:
SC-002 (BAY0-MC1-F50) Unfortunately, messages from x.x.x.x weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors
We have contacted our ISP, who told us it is a problem with our 2010 Exchange server.
We checked our IP in Outlook's Deliverability Support and it reported the following:
There are indications that the above IP(s) are engaged in namespace mining. Outlook.com is blocking all email sent from this IP.
What do we need to do to solve this problem?
You need make sure that your antivirus program is up to date on all workstations and servers.
Also make sure that you have proper spam filter for both incoming and out going emails.
Create SPF records for your domain.