mail.intersvyaz.net has no MX records.
Question and response
Question
dig mail.intersvyaz.net. MX
Answer
The response has no answer records.
Authority
intersvyaz.net. 10800 SOA ns1.is74.ru. hostmaster.is74.ru. 2018071825 10800 1800 604801 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0