Why Are PTR Records Important?

Anti-spam filters are designed to scrutinize the origins of email traffic. One common method is to verify that the sending server has a correctly configured PTR record :

How PTR Records Work

To illustrate how PTR records function, consider the following example:

1. A server with the IP address 192.0.2.123 sends an email.
2. The receiving server checks the PTR record for 192.0.2.123 and finds it maps to the domain mail.example.com
3. The receiving server then performs a forward lookup to verify that mail.example.com. resolves back to 192.0.2.123.

If the forward and reverse DNS records align, it establishes trustworthiness for the sending server.

Best Practices for Configuring PTR Records

Properly setting up PTR records is essential for organizations that manage their own mail servers. Here are three key practices to ensure optimal email deliverability:

Assign a PTR Record for Every Sending IP Address:

Each sending IP address must have a corresponding PTR record that points to a valid domain name.

For example:

123.2.0.192.in-addr.arpa. ---> mail.example.com  

Align Forward and Reverse DNS Lookups:
The forward (A record) and reverse (PTR record) DNS lookups should match. For example:

mail.example.com ---> 192.0.2.123 192.0.2.123 ---> mail.example.com.

Test and Monitor DNS Configuration Regularly:
Regularly verify your DNS configuration to ensure records remain accurate and aligned. This can be done using DNS lookup tools or specialized monitoring services.

Where to Configure PTR Records

PTR records are usually configured in the DNS control panel of the provider managing your IP addresses. If your email server resides on a cloud platform or hosting provider, contact them to set up the PTR record. Ensure that the name mapped by the PTR record corresponds to the domain you use for sending emails.

Conclusion

While the configuration of PTR records might seem like a technical detail, it is vital for building trust and ensuring email deliverability. Proper DNS configuration demonstrates professionalism and reduces the chances of being flagged by anti-spam systems. By following best practices such as aligning forward and reverse DNS records, regularly testing configurations, and ensuring each IP has a valid PTR record, organizations can avoid unnecessary disruptions to their email communications.