ns2.GTCONLINE.RU has no MX records.
Question and response
Question
dig ns2.GTCONLINE.RU. MX
Answer
The response has no answer records.
Authority
gtconline.ru. 3600 SOA ns1.gtconline.ru. root.ns1.gtconline.ru. 2018101502 10800 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0