ns01.agenturserver.co has no MX records.
Question and response
Question
dig ns01.agenturserver.co. MX
Answer
The response has no answer records.
Authority
agenturserver.co. 3600 SOA ns01.agenturserver.de. support.mittwald.de. 1755875460 28800 7200 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0