mx.intercorp.com.br has no CNAME records.
Question and response
Question
dig mx.intercorp.com.br. NS
Answer
The response has no answer records.
Authority
intercorp.com.br. 230 SOA ns.intercorp.com.br. administrador.intercorp.com.br. 2026011004 14400 3600 864000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0