Смотрим инфу дальше:
ns2.novaco.in. [85.237.51.193]
ns.novaco.in. [81.200.241.57]
Your 1 MX records are:
1 work.penek.org. [TTL=3600] IP=81.200.241.50 [TTL=3600]
The IPs of not all of your mail server(s) have correct reverse DNS (PTR) entries. The reverse DNS entries are:
50.241.200.81.in-addr.arpa. mail.thgp.ru. [TTL=86400]
Здесь обращаем внимание на это mail.thgp.ru