*.sardis.dedicated.theory7.net has no MX records.
Question and response
Question
dig *.sardis.dedicated.theory7.net. MX
Answer
The response has no answer records.
Authority
dedicated.theory7.net. 3600 SOA dns.theory7.net. hostmaster.dedicated.theory7.net. 2026021202 10800 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0