ns2.selectel.org has no MX records.
Question and response
Question
dig ns2.selectel.org. MX
Answer
The response has no answer records.
Authority
selectel.org. 43 SOA a.ns.selectel.ru. support.selectel.ru. 2026022104 10800 3600 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0