ptr.network has no MX records.
Question and response
Question
dig ptr.network. MX
Answer
The response has no answer records.
Authority
ptr.network. 3600 SOA ns1.reg.ru. hostmaster.ns1.reg.ru. 1757521541 14400 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0