systemdns.com has no MX records.
Question and response
Question
dig systemdns.com. MX
Answer
The response has no answer records.
Authority
systemdns.com. 300 SOA ns1.tucows.com. hostmaster.systemdns.com. 1771770975 10800 3600 2592000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0