mx1.spaceweb.RU has no CNAME records.
Question and response
Question
dig mx1.spaceweb.RU. NS
Answer
The response has no answer records.
Authority
spaceweb.RU. 22 SOA ns1.sweb.RU. postmaster.sweb.RU. 2022090962 7200 3600 14400 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0