hdc1.cz has no MX records.
Question and response
Question
dig hdc1.cz. MX
Answer
The response has no answer records.
Authority
hdc1.cz. 360 SOA ns.hdc1.cz. zeleni.heureka.cz. 2015111001 10800 3600 604800 360
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0