heimir.emsgrid.com has no MX records.
Question and response
Question
dig heimir.emsgrid.com. MX
Answer
The response has no answer records.
Authority
emsgrid.com. 1800 SOA lynn.ns.cloudflare.com. dns.cloudflare.com. 2395778270 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0