ns-a3.rogers.com has no MX records.
Question and response
Question
dig ns-a3.rogers.com. MX
Answer
The response has no answer records.
Authority
rogers.com. 900 SOA pub1-master2-iblox-ym.mgmt.net.rogers.com. cnrbacc.rci.rogers.com. 2017038188 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0