ns.rt-comm.ru has no MX records.
Question and response
Question
dig ns.rt-comm.ru. MX
Answer
The response has no answer records.
Authority
rt-comm.ru. 86400 SOA ns01.rtcomm.ru. dns.rtcomm.ru. 2026012601 28800 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0