cloud.rackray.com has no MX records.
Question and response
Question
dig cloud.rackray.com. MX
Answer
The response has no answer records.
Authority
rackray.com. 1800 SOA carioca.ns.cloudflare.com. dns.cloudflare.com. 2396649115 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0