auto.dnssmarthost.net has no MX records.
Question and response
Question
dig auto.dnssmarthost.net. MX
Answer
The response has no answer records.
Authority
auto.dnssmarthost.net. 7200 SOA ns1.siteground.net. admins.siteground.com. 1 43200 900 1814400 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0