smtp9999.selzymail.com has no MX records.
Question and response
Question
dig smtp9999.selzymail.com. MX
Answer
The response has no answer records.
Authority
selzymail.com. 180 SOA ns20.digicertdns.com. dns.digicertdns.com. 2009010185 43200 3600 1209600 180
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0