dns1.stabletransit.com has no MX records.
Question and response
Question
dig dns1.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