myshopify.com has no MX records.
Question and response
Question
dig myshopify.com. MX
Answer
The response has no answer records.
Authority
myshopify.com. 3600 SOA ns1.dnsimple.com. admin.dnsimple.com. 1477078353 86400 7200 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0