smtp-out.mailgate.de has no MX records.
Question and response
Question
dig smtp-out.mailgate.de. MX
Answer
The response has no answer records.
Authority
mailgate.de. 3600 SOA a.ns14.net. hostmaster.internetx.de. 2024111100 40000 7200 604800 3600
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0