libhost4.miramo.cz has no MX records.
Question and response
Question
dig libhost4.miramo.cz. MX
Answer
The response has no answer records.
Authority
miramo.cz. 3600 SOA miramo1.miramo.cz. hostmaster.miramo.cz. 202602090 3600 3600 3600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0