shops.shopify.com has no MX records.
Question and response
Question
dig shops.shopify.com. MX
Answer
The response has no answer records.
Authority
shopify.com. 1800 SOA gold.foundationdns.com. dns.cloudflare.com. 2397052600 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0