mx1.imcsas.com.co has no CNAME records.
Question and response
Question
dig mx1.imcsas.com.co. NS
Answer
The response has no answer records.
Authority
imcsas.com.co. 10233 SOA ns1.colombiahosting.com. sysadmin.colombiahosting.com.co. 2026011100 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0