ip-168.121.195.81.dtel.com.br has no MX records.
Question and response
Question
dig ip-168.121.195.81.dtel.com.br. MX
Answer
The response has no answer records.
Authority
dtel.com.br. 900 SOA d.sec.dns.br. hostmaster.registro.br. 2026043000 86400 900 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0