mx.telus.net has no CNAME records.
Question and response
Question
dig mx.telus.net. NS
Answer
The response has no answer records.
Authority
telus.net. 3600 SOA dns24.telus.com. dnsadmin2.telus.com. 2018081064 900 7200 3600000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0