sharedb3.c70.your-storageshare.de has no MX records.
Question and response
Question
dig sharedb3.c70.your-storageshare.de. MX
Answer
The response has no answer records.
Authority
your-storageshare.de. 10 SOA ns1.first-ns.de. postmaster.your-storageshare.de. 1771919258 180 60 3600000 10
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0