cucl2.de has no MX records.
Question and response
Question
dig cucl2.de. MX
Answer
The response has no answer records.
Authority
cucl2.de. 300 SOA root-dns.netcup.net. dnsadmin.netcup.net. 2026020642 27000 27000 27000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0