prime-pool.xbox-dns.ru has no MX records.
Question and response
Question
dig prime-pool.xbox-dns.ru. MX
Answer
The response has no answer records.
Authority
xbox-dns.ru. 300 SOA ns1.timeweb.ru. dns.timeweb.ru. 173 28800 7200 259200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0