static.218.76.46.78.clients.your-server.de has no MX records.
Question and response
Question
dig static.218.76.46.78.clients.your-server.de. MX
Answer
The response has no answer records.
Authority
46.78.clients.your-server.de. 600 SOA ns1.your-server.de. postmaster.your-server.de. 2010112900 86400 1800 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0