ns2.us.impsat.net has no MX records.
Question and response
Question
dig ns2.us.impsat.net. MX
Answer
The response has no answer records.
Authority
impsat.net. 3600 SOA ns1.us.impsat.net. hostmaster.impsat.net. 1764832216 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0