mailmx.smtp.hu has no MX records.
Question and response
Question
dig mailmx.smtp.hu. MX
Answer
The response has no answer records.
Authority
smtp.hu. 300 SOA ns1.vhost.hu. hostmaster.vhost.hu. 1758026867 3600 7200 604800 300
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0