mx783.umbler.com.br has no MX records.
Question and response
Question
dig mx783.umbler.com.br. MX
Answer
The response has no answer records.
Authority
umbler.com.br. 60 SOA umblerdns03.westeros.local. admin.umbler.com. 94 60 900 345600 60
Additional
. 0 OPT ; payload 4000, xrcode 0, version 0, flags 0