sns.btc-net.bg has no MX records.
Question and response
Question
dig sns.btc-net.bg. MX
Answer
The response has no answer records.
Authority
btc-net.bg. 3600 SOA ns.btc-net.bg. root.ns.btc-net.bg. 2023111402 10800 3600 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0