mail02.mail-gw.de has no MX records.
Question and response
Question
dig mail02.mail-gw.de. MX
Answer
The response has no answer records.
Authority
mail-gw.de. 600 SOA dns.dns1.de. hostmaster.internetwire.de. 2026012802 28800 7200 604800 600
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0