mail.nfv.gtt.net has no MX records.
Question and response
Question
dig mail.nfv.gtt.net. MX
Answer
The response has no answer records.
Authority
nfv.gtt.net. 600 SOA ns5-build.gtt.net. hostmaster.gtt.net. 2026022627 10800 900 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0