mail.metronet.cz has no MX records.
Question and response
Question
dig mail.metronet.cz. MX
Answer
The response has no answer records.
Authority
metronet.cz. 360 SOA ns1.metronet.cz. hostmaster.metronet.cz. 2026020416 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0