dns4.uni5.net has no MX records.
Question and response
Question
dig dns4.uni5.net. MX
Answer
The response has no answer records.
Authority
uni5.net. 3600 SOA dns1.uni5.net. abuse.uni5.net. 2023011902 3600 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0