ns2.shellit.org has no MX records.
Question and response
Question
dig ns2.shellit.org. MX
Answer
The response has no answer records.
Authority
shellit.org. 1800 SOA ian.ns.cloudflare.com. dns.cloudflare.com. 2398484770 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0