mail.staybox.com.br has no MX records.
Question and response
Question
dig zimbra002.staybox.com.br. MX
Answer
The response has no answer records.
Authority
staybox.com.br. 86400 SOA ns0.staybox.com.br. servidores.staybox.com.br. 2026021901 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0