mx1.stsmail.ro has no CNAME records.
Question and response
Question
dig mx1.stsmail.ro. NS
Answer
The response has no answer records.
Authority
stsmail.ro. 542 SOA ns1.stsisp.ro. root.stsisp.ro. 2026011901 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0