185.244.166.15.lumaserv.com has no MX records.
Question and response
Question
dig 185.244.166.15.lumaserv.com. MX
Answer
The response has no answer records.
Authority
lumaserv.com. 1800 SOA isla.ns.cloudflare.com. dns.cloudflare.com. 2398279775 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0