smtp3.radiant.net has no MX records.
Question and response
Question
dig smtp3.radiant.net. MX
Answer
The response has no answer records.
Authority
radiant.net. 600 SOA dns60.telus.com. dnsadmin2.telus.com. 2025070396 600 7200 3600000 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0