NSLOOKUP
At the command prompt type “NSLOOKUP “.
This will give you a “>” prompt.
Type “set type=MX “.
Type “microsoft.com “.
You should now get the MX records for “microsoft.com”:
Non-authoritative answer:
microsoft.com MX preference = 10, mail exchanger = microsoft-com.mail.protection.outlook.com

microsoft-com.mail.protection.outlook.com internet address = 207.46.163.215
microsoft-com.mail.protection.outlook.com internet address = 207.46.163.247
microsoft-com.mail.protection.outlook.com internet address = 207.46.163.138

Or Use who.is:
http://who.is/

Telnet:
Using Telnet from Windows to test port 25, from the command prompt window type:

telnet server port
Example:
telnet mail.eircom.net 25
or whoever the SP is ..

TELNET – BLACKLISTED:
521 connection rejected
Connection to host lost.

Blacklist lookup/release:
http://www.fortiguard.com/static/ip_lookup.html

Tools:
http://mxtoolbox.com/NetworkTools.aspx