_spf-mails.wia.cz has no MX records.
Question and response
Question
dig _spf-mails.wia.cz. MX
Answer
The response has no answer records.
Authority
wia.cz. 3600 SOA ns1.wia.cz. hostmaster.wia.cz. 2026030606 86400 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0