smtpb.grapesc.cz has no MX records.
Question and response
Question
dig smtpb.grapesc.cz. MX
Answer
The response has no answer records.
Authority
grapesc.cz. 600 SOA ns1.grapesc.cz. domeny.grapesc.cz. 2025501073 10800 7200 1209600 600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0