nas-18.dialup.penza.com.ru has no MX records.
Question and response
Question
dig nas-18.dialup.penza.com.ru. MX
Answer
The response has no answer records.
Authority
penza.com.ru. 1200 SOA ns.penza.com.ru. dnsmaster.penza.com.ru. 2025111801 14400 3600 1814400 1200
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0