spf.mindbox.ru has no CNAME records.
Question and response
Question
dig spf.mindbox.ru. NS
Answer
The response has no answer records.
Authority
mindbox.ru. 300 SOA ns1.edgedns.co. support.edgecenter.ru. 1772032656 5400 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0