how to check the mx record with nslookup

Open a Command Prompt
nslookup
Server (The DNS server that you want to use. This is optional.)
Set q=mx (This sets the query type to "MX" {Mail Exchanger}.)
domain.com (The domain name you want to lookup the mail exchanger to.)
This operation can be done on Windows XP, Windows Server 2003, and Windows Vista. There are similar options if you are doing this from Linux.
Open up a terminal
nslookup
Set type=mx (This sets the query type to "MX" {Mail Exchanger}.)
domain.com (The domain name you want to lookup the mail exchanger to.)