ksmg.retnnet.ru has no MX records.
Question and response
Question
dig ksmg.retnnet.ru. MX
Answer
The response has no answer records.
Authority
retnnet.ru. 3600 SOA nsa.retn.net. noc.retn.net. 2025052700 900 600 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0