pve-pbx1.baupart.de has no MX records.
Question and response
Question
dig pve-pbx1.baupart.de. MX
Answer
The response has no answer records.
Authority
baupart.de. 600 SOA ns1069.ui-dns.com. hostmaster.1und1.com. 2017060216 28800 7200 604800 600
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0