Experts, marketers, and technical documentation collectively agree that matching reverse DNS (rDNS) with the SMTP banner and HELO/EHLO is crucial for optimal email deliverability. It serves as a fundamental check to verify the legitimacy of the sending server, build trust with receiving mail servers, and prevent emails from being flagged as spam. While one expert suggests that the rDNS to SMTP banner match mainly applies to inbound mail and may not always cause deliverability issues if mismatched, the broader consensus emphasizes that a correct configuration significantly enhances sender reputation and ensures mail stream accountability. Modern mail providers are becoming increasingly strict, making proper rDNS setup an essential best practice.
11 marketer opinions
The consensus from email marketers across various platforms is that matching reverse DNS (rDNS) with the SMTP banner is highly important for email deliverability. A properly configured rDNS record verifies that the sending IP address is authorized to send emails for the domain it claims to represent, building trust with receiving mail servers and reducing the likelihood of emails being marked as spam. While a mismatch may not always guarantee deliverability issues, it can raise red flags and negatively impact sender reputation. Aligning these elements is considered a basic and often trivial step towards ensuring optimal email delivery.
Marketer view
Email marketer from SparkPost explains that Reverse DNS (rDNS) is important because it helps to verify that the IP address sending the email is authorized to send email for the domain it claims to represent. A matching rDNS record builds trust with receiving mail servers and improves email deliverability.
5 Jul 2023 - SparkPost
Marketer view
Email marketer from Mailjet shares that a reverse DNS lookup is a query to determine the domain name associated with an IP address. It helps email servers verify the authenticity of incoming emails. If the reverse DNS record doesn't match the sending domain, it can negatively impact deliverability.
10 Feb 2024 - Mailjet
5 expert opinions
Experts emphasize that aligning reverse DNS (rDNS) with the SMTP banner and HELO/EHLO is important for email deliverability and sender reputation. While one expert notes it primarily applies to inbound mail and a mismatch might not break things, it's generally seen as a sign of a well-configured server. Correct rDNS helps verify the legitimacy of the sending IP address, build trust with receiving mail servers, and ensures mail administrators can identify and trust the source of the mail stream. SpamResource particularly highlights it as a cornerstone of good IP/domain reputation and an increasingly important anti-spam measure, as spammers rarely configure it correctly.
Expert view
Expert from Email Geeks explains that unless they are confused, reverse DNS matching SMTP banner only applies to inbound mail. While not a big deal, it's a sign the mail server may not know its hostname.
10 Oct 2021 - Email Geeks
Expert view
Expert from Email Geeks explains that for deliverability, sender server configuration and DNS are key. A matching hostname in HELO and DNS is a good sign. While a mismatch won't break anything, aligning them looks more competent and professional.
13 Nov 2022 - Email Geeks
4 technical articles
Technical documentation from Google, Microsoft, the RFC Editor, and cPanel consistently emphasizes the importance of having a valid PTR record that matches the sending IP address to your domain for email deliverability. A mismatch can lead to emails being marked as spam. A matching PTR record verifies the legitimacy of outbound emails, builds trust, and improves deliverability rates by confirming the server is authorized to send emails on behalf of the domain. While the RFC doesn't explicitly focus on matching reverse DNS, it mandates that SMTP servers send a valid domain name in the EHLO or HELO command.
Technical article
Documentation from Microsoft Docs shares that having a matching PTR record for your mail server's IP address pointing to your domain is important for verifying the legitimacy of your outbound emails. It helps in building trust and improves deliverability rates, as it confirms that the server is authorized to send emails on behalf of the domain.
20 Aug 2023 - Microsoft Docs
Technical article
Documentation from Google Workspace Admin Help explains that setting up a valid PTR record that matches the sending IP address to your domain is crucial. A mismatch can cause email to be marked as spam.
31 Mar 2023 - Google Workspace Admin Help
Do PTR records and HELOs impact email deliverability?
How do I check if the sending IP address matches the IP address of the hostname specified in the Pointer (PTR) record?
How do I configure reverse DNS (rDNS) with multiple IP addresses for email sending?
How do I perform a reverse DNS lookup and interpret the results?
How does missing or different reverse DNS (rDNS) impact email deliverability, and when is a dedicated IP address needed?