28.72.75.177.in-addr.arpa has no MX records.
Question and response
Question
dig 28.72.75.177.in-addr.arpa. MX
Answer
The response has no answer records.
Authority
72.75.177.in-addr.arpa. 86400 SOA ns-rev-01.tely.com.br. root.ns-rev-01.tely.com.br. 2018072500 604800 86400 2419200 604800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0