OS-CAR.RU has no MX records.
Question and response
Question
dig OS-CAR.RU. MX
Answer
The response has no answer records.
Authority
OS-CAR.RU. 600 SOA ns3.nic.RU. admin.OS-CAR.RU. 1756000088 1440 3600 259200 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0