tableauonline.cogeco.com has no MX records.
Question and response
Question
dig tableauonline.cogeco.com. MX
Answer
The response has no answer records.
Authority
cogeco.com. 86400 SOA ns1.cgocable.net. hostmaster.cgocable.ca. 2003093162 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0