isp4.wm.ru has no MX records.
Question and response
Question
dig isp4.wm.ru. MX
Answer
The response has no answer records.
Authority
wm.ru. 3600 SOA ns.wm.ru. support.wm.ru. 2016032807 28800 3600 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0