ns.kontur.host has no MX records.
Question and response
Question
dig ns.kontur.host. MX
Answer
The response has no answer records.
Authority
kontur.host. 300 SOA ns.kontur.host. balancers.skbkontur.ru. 2026030600 10000 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0