dns1.mtu.RU has no MX records.
Question and response
Question
dig dns1.mtu.RU. MX
Answer
The response has no answer records.
Authority
mtu.ru. 600 SOA dns0.mtu.ru. dns.mts.ru. 2025092603 1200 60 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0