smtp09.enbridge.com has no MX records.
Question and response
Question
dig smtp09.enbridge.com. MX
Answer
The response has no answer records.
Authority
enbridge.com. 1800 SOA blue.foundationdns.com. webpresence.enbridge.com. 2397886980 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0