c0.nic.global has no MX records.
Question and response
Question
dig c0.nic.global. MX
Answer
The response has no answer records.
Authority
nic.global. 300 SOA a0.nic.global. alerts.afilias.info. 1771961587 3600 600 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0