I switched from a shared account to a VPS account (different hosting providers) and have been trying to learn my way through all the toys I get with my new found freedom. One of the things that's been boggling my mind is the RDNS information for my sites.
The VPS 'package' I have gives me four IP addresses, and they all point, of course, to the same server I'm on. I've got many different domains and as of this moment all, save one, are pointed to the main IP on my account.. call it nnn.67 for the sake of argument. I also have nnn.68,nnn.69 and nnn.70. The one site that's has its own IP is on the nnn.70 IP, and I give it one of its own because I sell things on it. The problem is that ever since the move my customers have been reporting that they're not receiving my confirmation e-mails. I'd say about 70% or so are NOT getting through. With no confirmation the sale doesn't officially complete, so I've been needing to manually take care of them.
When I contacted the hosting company about the RDNS information, they set the main address nnn.67 to point to the master domain name on my account, which is great... that's what I want. The problem is that when I do a RDNS lookup on any of my other IP addresses, including the one my commerce site sits on, I get nothing... nada... no record found. When I ask the hosting company about that, they tell me that the RDNS for my account is set up correctly since the main IP reflects the main domain name.
I've asked twice, and both times they tell me it's correct... and each time I check and the extra IPs on my account all say Non-existent domain (with a nslookup). Am I just being a hosting newbie here and worrying about nothing, or could this be the reason that 70% of my outgoing e-mail is either not reaching my customers or getting sent to the junk folder?
If I have a legitimate concern, I wonder why my host is being so dense... they're 'known' for their customer service, so it kinda makes me think maybe I'm just not understanding how the whole thing works with multiple IPs on one account.