sm001sy.metricstream.com has no MX records.
Question and response
Question
dig sm001sy.metricstream.com. MX
Answer
The response has no answer records.
Authority
metricstream.com. 1800 SOA elle.ns.cloudflare.com. dns.cloudflare.com. 2397942926 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0