mx1.MIRAN.RU has no CNAME records.
Question and response
Question
dig mx1.MIRAN.RU. NS
Answer
The response has no answer records.
Authority
miran.ru. 3301 SOA ns.miran.ru. noc.miran.ru. 2019055350 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0