ns1.mxt.net.br has no MX records.
Question and response
Question
dig ns1.mxt.net.br. MX
Answer
The response has no answer records.
Authority
mxt.net.br. 86400 SOA ns1.mxt.net.br. sac.mxt.net.br. 2024102101 28800 14400 360000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0