Our Organization was just blocked from sending emails to @hotmail.com etc addresses. Every time we get a delivery failure which reads:

   "         There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.

            <<hostname removed> #5.5.0 smtp;550 SC-002 (COL0-MC2-F20) Unfortunately, messages from <IP removed> 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 submitted a ticket and received the reply:

"There are indications that the above IP(s) are engaged in namespace mining. Outlook.com is blocking all email sent from this IP.

You must correct the problem and you must stop the behavior described above. We recommend that you work with your email or network administrator to review the logs of your email servers. Check the sending log files and concentrate on logs that are sending to nonexistent @hotmail.com, @live.com, @msn.com, @outlook.com?with multiple tries and failures."

We're assuming this must mean someone was infected with a virus but can't find any mass mailouts in the SMTP logs in the past month. We don't do any mass mailouts as part of our business. We don't know how to proceed from here. Will we be automatically unblocked after some time or what? Is there someone we can work with to resolve this? If so, there is no information on online on who to actually contact.