mx.gotobg.net has no CNAME records.
Question and response
Question
dig mx.gotobg.net. NS
Answer
The response has no answer records.
Authority
gotobg.net. 10800 SOA ns1.gotobg.net. admin.goto.bg. 2025022001 28800 7200 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0