How To Set Up Reverse DNS For Multiple Email Domains

Obviously you can only have one reverse DNS (PTR) record per email address, so how do you set up reverse DNS for multiple email domains sharing a single IP?

To set up multiple reverse DNS records is impossible, but there is a solution to the very common problem. The solution is to pick a “main” email address domain and set a reverse DNS record for that, then create an SPF DNS record that says that the other domains are allowed to send email from that domain’s IP.

❗ Tip: There some really handy SPF record generators available on the internet.
❗ Tip: For most people, your ISP is responsible for your reverse DNS records, not the folk that host your DNS.