mail.cjmb.us has no CNAME records.
Question and response
Question
dig mail.cjmb.us. NS
Answer
The response has no answer records.
Authority
cjmb.us. 410 SOA veronica.ns.cloudflare.com. dns.cloudflare.com. 2397006919 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0