mta.dashasender.ru has no CNAME records.
Question and response
Question
dig mta.dashasender.ru. NS
Answer
The response has no answer records.
Authority
dashasender.ru. 7200 SOA ns1.nameself.com. support.regtime.net. 1759846445 300 300 604800 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0