mail.bg.net.ua has no MX records.
Question and response
Question
dig mail.bg.net.ua. MX
Answer
The response has no answer records.
Authority
bg.net.ua. 86400 SOA ns.bg.net.ua. hostmaster.bg.net.ua. 2025033100 3600 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0