mail2.duerr-gruppe.at has no MX records.
Question and response
Question
dig mail2.duerr-gruppe.at. MX
Answer
The response has no answer records.
Authority
duerr-gruppe.at. 1800 SOA charles.ns.cloudflare.com. dns.cloudflare.com. 2396335489 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0