mx118.smartmail2.com.ar has no CNAME records.
Question and response
Question
dig mx118.smartmail2.com.ar. NS
Answer
The response has no answer records.
Authority
com.ar. 1589 SOA e.dns.ar. noc.nic.gob.ar. 2026022423 600 300 1728000 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0