infomain.net.ar has no MX records.
Question and response
Question
dig infomain.net.ar. MX
Answer
The response has no answer records.
Authority
infomain.net.ar. 3600 SOA ns1.infomain.net.ar. soporte.infomain.net.ar. 6 7200 540 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0