mx0.HOSTER.RU has no CNAME records.
Question and response
Question
dig mx0.HOSTER.RU. NS
Answer
The response has no answer records.
Authority
HOSTER.RU. 953 SOA ns10.HOSTER.RU. support.HOSTER.RU. 3509107393 3600 300 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0