What is Reverse DNS?

Reverse DNS (rDNS) is name resolution that looks up an IP addresses to obtain a domain name, performing the opposite function of the DNS server, which turns domain names into IP addresses.

Reverse DNS can be used as a spam filter. Typically, spammers use invalid IP addresses, that is, ones that do not match domain names. A reverse DNS program looks up the IP address of an incoming message and, if no valid domain name is found, the server blocks the message. Although reverse DNS is fairly effective for filtering spam, it also often blocks valid emails.

We automatically configure reverse DNS for all our email services. Due to IP ownership restrictions, we do not allow custom reverse DNS settings for our services or products at this time. There are, however, options for managing reverse DNS within our dedicated server offerings.

 Note: Do not use a PTR record to configure reverse DNS in our system.

More info

• Manage DNS records
• Set up my Microsoft 365 account