kuf.gblnet.net has no MX records.
Question and response
Question
dig kuf.gblnet.net. MX
Answer
The response has no answer records.
Authority
kuf.gblnet.net. 86400 SOA ns.gblnet.ru. vvv.gblnet.ru. 2023020101 10800 1200 1209600 259200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0