ns3.telefonica.de has no MX records.
Question and response
Question
dig ns3.telefonica.de. MX
Answer
The response has no answer records.
Authority
telefonica.de. 600 SOA ns1.telefonica.de. hostmaster\.de.telefonica.com. 2057 28800 7200 604800 600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0