mx-n02.wc2.dfw1.stabletransit.com has no MX records.
Question and response
Question
dig mx-n02.wc2.dfw1.stabletransit.com. MX
Answer
The response has no answer records.
Authority
stabletransit.com. 300 SOA ns1.hostingmatrix.net. admin.helpmachine.com. 1583180440 3600 300 1814400 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0