mx.synacordomains.net has no MX records.
Question and response
Question
dig mx.synacordomains.net. MX
Answer
The response has no answer records.
Authority
synacordomains.net. 3600 SOA dns1.name-services.com. info.name-services.com. 1644677301 172800 900 1814400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0