_spf.1und1.de has no MX records.
Question and response
Question
dig _spf.1und1.de. MX
Answer
The response has no answer records.
Authority
1und1.de. 600 SOA ns-1and1.ui-dns.de. dnsadmin.1und1.de. 2013092287 10800 3600 604800 600
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0