sg01.smilehost.net has no MX records.
Question and response
Question
dig sg01.smilehost.net. MX
Answer
The response has no answer records.
Authority
smilehost.net. 1800 SOA joan.ns.cloudflare.com. dns.cloudflare.com. 2396432932 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0