mx.partnergate.de has no MX records.
Question and response
Question
dig mx.partnergate.de. MX
Answer
The response has no answer records.
Authority
partnergate.de. 300 SOA anycast.regdns1.de. hostmaster.partnergate.de. 2025100700 28800 7200 604800 300
Additional
. 0 OPT ; payload 1400, xrcode 0, version 0, flags 0