dnsxau.threembb.net has no MX records.
Question and response
Question
dig dnsxau.threembb.net. MX
Answer
The response has no answer records.
Authority
threembb.net. 86400 SOA udns1.cscdns.net. hostmaster.cscdns.net. 2026020917 86400 86400 86400 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0