mx1.rz-ip.net has no MX records.
Question and response
Question
dig mx1.rz-ip.net. MX
Answer
The response has no answer records.
Authority
rz-ip.net. 1800 SOA pns.rz-ip.net. hostmaster.rz-ip.net. 2025021203 10800 3600 3600000 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0