ns110.slinkdns.net has no MX records.
Question and response
Question
dig ns110.slinkdns.net. MX
Answer
The response has no answer records.
Authority
slinkdns.net. 1800 SOA dolly.ns.cloudflare.com. dns.cloudflare.com. 2395877387 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0