ns2.cps.com.ar has no MX records.
Question and response
Question
dig ns2.cps.com.ar. MX
Answer
The response has no answer records.
Authority
cps.com.ar. 43200 SOA ns1.cps.com.ar. hostmaster.cps.com.ar. 2006092983 3600 900 2419200 43200
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0