sbnettelecom.net.br has no MX records.
Question and response
Question
dig sbnettelecom.net.br. MX
Answer
The response has no answer records.
Authority
sbnettelecom.net.br. 900 SOA d.sec.dns.br. hostmaster.registro.br. 2026039000 86400 900 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0