b2.nic.blue has no MX records.
Question and response
Question
dig b2.nic.blue. MX
Answer
The response has no answer records.
Authority
nic.blue. 300 SOA a0.nic.blue. alerts.afilias.info. 1771831984 86400 7200 3600000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0