15.53.224.104.us.kuroit.com has no MX records.
Question and response
Question
dig 15.53.224.104.us.kuroit.com. MX
Answer
The response has no answer records.
Authority
kuroit.com. 1800 SOA chris.ns.cloudflare.com. dns.cloudflare.com. 2397790933 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0