ns.rnc.ro has no MX records.
Question and response
Question
dig ns.rnc.ro. MX
Answer
The response has no answer records.
Authority
rnc.ro. 900 SOA ns-a.rnc.ro. net-admin.rnc.ro. 1771779806 36000 14400 2419200 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0