smtp.cra.cz has no MX records.
Question and response
Question
dig smtp.cra.cz. MX
Answer
The response has no answer records.
Authority
cra.cz. 3600 SOA ns.cra.cz. dmz.radiokomunikace.cz. 2026022600 10800 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0