ns4.vibrantbb.net has no MX records.
Question and response
Question
dig ns4.vibrantbb.net. MX
Answer
The response has no answer records.
Authority
vibrantbb.net. 3600 SOA ns3.vibrantbb.net. admin.vibrantbb.net. 2023101101 1200 120 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0