s3.infos.cz has no MX records.
Question and response
Question
dig s3.infos.cz. MX
Answer
The response has no answer records.
Authority
infos.cz. 10800 SOA ns.infos.cz. infosys.infos.cz. 2026021601 7200 3600 1209600 10800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0