mail.gransy.com has no CNAME records.
Question and response
Question
dig mail.gransy.com. NS
Answer
The response has no answer records.
Authority
gransy.com. 1800 SOA ns1.anycastdns.cz. root.gransy.com. 2767575306 86400 900 1209600 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0