mail.nadejda.net has no MX records.
Question and response
Question
dig mail.nadejda.net. MX
Answer
The response has no answer records.
Authority
nadejda.net. 3600 SOA ns.datalink.bg. admin.datalink.bg. 424 900 600 86400 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0