mo01.vodafone.de has no MX records.
Question and response
Question
dig mo01.vodafone.de. MX
Answer
The response has no answer records.
Authority
vodafone.de. 900 SOA ns-admin.vodafone.com. hostmaster.vodafone.com. 2008077347 14400 1440 604800 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0