dave.ns.black.host has no MX records.
Question and response
Question
dig dave.ns.black.host. MX
Answer
The response has no answer records.
Authority
black.host. 1800 SOA dave.ns.black.host. dns.cloudflare.com. 2396487332 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0