I run Postfix and I need my server's public IP address to be resolving to mail.mysite.com
I know that we have a PTR record for that AKA rDNS.
It's all nice, but something confuses me here. I know that there's a way (somewhat complicated though) to set up a PTR record in BIND. I think there' s a separate file for that etc. But that's not my question here. I know that some people apply to their ISP so that the ISP would set up the correct hostname for the IP that it's lending to its customer. So that some picky SMTP servers out there will accept the mail that's being sent to them.
My question is:
What's the right way to do it and what's the difference between setting up a PTR in BIND configuration yourself and asking your ISP to do it for you. To me it sounds like a contradiction.