nidavellir.zubrodev.cz has no MX records.
Question and response
Question
dig nidavellir.zubrodev.cz. MX
Answer
The response has no answer records.
Authority
zubrodev.cz. 900 SOA ns.web4u.cz. admin.web4u.cz. 2017111301 10800 3600 1209600 14400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0