Reverse-DNS is an important security aid for your own-hosted mailserver. It is well covered in my manuals below, but only for IPv4 type ip addresses, not for IPv6. Fortunately, adding IPv6 support is easy, according to the following checklist.
- Visit your hosting provider control panel and add an AAAA record named "mail" with the IPv6 address assigned by your VPS provider. The IPv6 address follows this format: 2a02:c207:2147:7713::1 or can also be expanded into a slightly longer format, but in any case is easily distinguishable from the old-style ip address.
- In your VPS provider control panel, there will be a facility for editing the reverse-DNS record, also known as the PTR record. Set the record to point to your hostname, of the format "mail.myhost.xxx"
- Edit your postfix configuration file to have inet_protocols = all instead of inet_protocols = ipv4. Of course, restart the postfix service after making this edit.
The instructions above are given in the context of the Apache web server setup described in full detail in my two VPS guides. These manuals are not expensive to buy and will save you hours of wasted time and grief trying to get your VPS servers to work reliably and securely.
Some good advice: Avoid using AI to answer all your VPS questions. AI can be incredibly useful, although it quite often gives flawed answers, but the weakness of using AI is it only responds to the questions you ask. This is fine if you know the field well enough to be asking the right questions, but if you are relatively new to the subject you need someone to teach you all the steps required to get your servers working reliably and, more importantly: safely. Hence the wisdom of spending a very small amount of cash on a comprehensive manual based on hard-won personal human experience of the task.
