dns2.corbina.net has no MX records.
Question and response
Question
dig dns2.corbina.net. MX
Answer
The response has no answer records.
Authority
corbina.net. 3600 SOA dns1.corbina.net. hostmaster.corbina.net. 1771439701 3600 300 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0