mx.tie.cl has no CNAME records.
Question and response
Question
dig mx.tie.cl. NS
Answer
The response has no answer records.
Authority
tie.cl. 2685 SOA nsaut.tie.cl. oper.isp.tie.cl. 2020101242 10800 900 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0