mx.junkemailfilter.com has no CNAME records.
Question and response
Question
dig mx.junkemailfilter.com. NS
Answer
The response has no answer records.
Authority
junkemailfilter.com. 2267 SOA ns.reality-dns.com. dns.reality-dns.com. 2024083000 28800 900 604800 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0