I successfully created my own email server running on Ubuntu but other mail servers refuse incoming mails from my server because there is no reverse dns (PTR record). The configuration looks like
- own domain name, let's say example.com
- one internet static IP address from ISP, let's say 18.104.22.168
- using a free dns service I was able to configure dns records except PTR record
- the dns servers are set on domain registrar
- router/gateway from ISP, which is not the domain registrar, having above external IP and internal IP 192.168.0.1
- a small PC with static internal IP 192.168.0.2 which runs mail server
Four distinct entities are in this setup: own mail server, ISP, domain registrar and dns service.
Is it possible having my own name server providing the required PTR record? I'm not sure if ISP is willing to help a tiny customer like me regarding PTR record. If it is possible setting up a name server, how bind9 can be configured in this case assuming there are no blocked ports? Other better alternatives? Currently I'm studying bind9 configurations.