mail3.stsmail.ro has no MX records.
Question and response
Question
dig mail3.stsmail.ro. MX
Answer
The response has no answer records.
Authority
stsmail.ro. 600 SOA ns1.stsisp.ro. root.stsisp.ro. 2026011901 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0