s3-w.ca-central-1.amazonaws.com has no MX records.
Question and response
Question
dig s3-w.ca-central-1.amazonaws.com. MX
Answer
The response has no answer records.
Authority
s3-w.ca-central-1.amazonaws.com. 10800 SOA ns-409.awsdns-51.com. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 293
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0