MSK.RU has no MX records.
Question and response
Question
dig MSK.RU. MX
Answer
The response has no answer records.
Authority
MSK.RU. 3600 SOA ns3-geo.nic.RU. hostmaster.nic.RU. 387863 7200 900 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0