207.2.in-addr.arpa has no MX records.
Question and response
Question
dig 207.2.in-addr.arpa. MX
Answer
The response has no answer records.
Authority
207.2.in-addr.arpa. 7200 SOA ns1.arcor-ip.de. hostmaster.adm.arcor.net. 2022030800 28800 14400 1814400 7200
Additional
. 0 OPT ; payload 1460, xrcode 0, version 0, flags 0