Namespace mining

Check the bewow article and  find out who has blacklisted you.
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.

http://www.theemailadmin.com/2010/12/how-to-prevent-namespace-mining/

go to www.whatismyip.com and know ur public ip address

first of all check your servers public ip address : for blacklist

go to mxtoolbox.com > blacklists and enter your server's public ip address

over there and check whether your server's public ip address is blacklisted or not

then if blacklisted then comes the scenario when you need to whitelist it from your side.

Had to follow a series of checks to be sure our systems were secure, then Microsoft unblocked us.

who did you contact at Microsoft?
We are having the same problems, we submit a request to delist however it keeps getting rejected. Our work is now heavily effected.
We even joined their recommended programs... (JMRP)  (SNDS)

Any extra information would be extremely helpful.
What checks have they had you perform?

I'm currently unable to locate where we found the email, but there was a form we filled out that sent a request to the Outlook.com Deliverability Support Team.  We received a response from them letting us know they had investigated our IP and confirmed namespace mining occurred.  They included in the email a list of things we needed to check and then confirm to them we had done.  We did the following things from the list:


We opened a case with Microsoft paid support to help us accomplish some of these, and since it was a hotmail issue they didn't end up charging us.  After letting the Outlook Deliverability Support team know we'd done all these things, they unblocked us.

Thanks:)

Hello,
I've Got this issue 2 days back. and i filled the form at

https://support.live.com/eform.aspx?productKey=edfsmsbl3&ct=eformts&scrx=1 

I got this reply :

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

Namespace mining is a method commonly used by malicious senders to generate lists of email addresses. This approach uses automation to sift through possible email names seeking to identify valid email addresses, e.g., Joe@domain.com, John@domain.com, and Josy@domain.com.

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.

What to do next? can you help please?

Thanks

I have this same problem and have initiated a trouble call to Microsoft Tech Support.