ns.sibmediafon.ru has no MX records.
Question and response
Question
dig ns.sibmediafon.ru. MX
Answer
The response has no answer records.
Authority
sibmediafon.ru. 3600 SOA ns.sibmediafon.ru. root.sibmediafon.ru. 2018042001 7200 900 3600000 36000
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0