mda050.dev.sendnode.com has no MX records.
Question and response
Question
dig ingress.dev.sendnode.com. MX
Answer
The response has no answer records.
Authority
sendnode.com. 360 SOA a.ns14.net. domainadmin.w3work.de. 2025120912 43200 7200 1209600 360
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0