Some information related to Microsoft blacklisting:

https://technet.microsoft.com/en-us/library/dn458545%28v=exchg.150%29.aspx

https://mail.live.com/mail/services.aspx

A form to declare valid IP from your domain:

https://support.microsoft.com/en-us/getsupport?oaspworkflow=start_1.0.0.0&wfname=capsub&productkey=edfsmsbl3&locale=en-us&ccsid=635786776026032458

Look at your logs

Look at the message in your mail log. You should see the email address of a contact. You can also directly send an email to delist@messaging.microsoft.com

Check with a tool

A good tool to check if you are blacklisted: http://mxtoolbox.com/blacklists.aspx

Check you DNS zone file

Once blacklisted, make sure you are correctly setup on your side and check your DNS zone file: – SPF record – PTR

Send an email to gmail.com or yahoo and check the email header, it contains details regarding SPAM detection and SPF check.