host.colocrossing.com has no MX records.
Question and response
Question
dig host.colocrossing.com. MX
Answer
The response has no answer records.
Authority
colocrossing.com. 1800 SOA brad.ns.cloudflare.com. dns.cloudflare.com. 2396222967 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0