s4.fe.registro.br has no MX records.
Question and response
Question
dig s4.fe.registro.br. MX
Answer
The response has no answer records.
Authority
registro.br. 900 SOA a.dns.br. hostmaster.registro.br. 2026030700 1800 900 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0