mx.runity.ru has no CNAME records.
Question and response
Question
dig mx.runity.ru. NS
Answer
The response has no answer records.
Authority
runity.ru. 151 SOA cdnsa.nic.ru. noc-dns.nic.ru. 2026022201 14400 3600 2592000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0