Summary
Reverse DNS (rDNS) is a fundamental element in email deliverability, acting as a crucial authentication mechanism. It verifies that the IP address sending email is authorized to do so for the domain it claims to represent. This process builds trust with Internet Service Providers (ISPs) and receiving mail servers by confirming the sender's identity and legitimacy. rDNS provides a means for recipient servers to check if the IP address matches the claimed domain, which helps prevent spoofing, reduces the likelihood of emails being flagged as spam, and improves overall delivery rates. Mailbox providers often prefer or even require valid rDNS. Forward Confirmed Reverse DNS (FCrDNS) further strengthens this verification by ensuring a reciprocal relationship between the domain name and IP address. Properly configured rDNS plays a vital role in enhancing sender reputation and ensuring that emails reach their intended recipients.
Key findings
- Authentication & Verification: rDNS acts as a primary means of verifying the authenticity of the sending mail server.
- Trust & Credibility: It establishes trust with ISPs and receiving mail servers.
- Deliverability Enhancement: Correctly configured rDNS improves email deliverability rates.
- Spam Prevention: It reduces the likelihood of emails being marked as spam or blocked.
- Compliance Requirement: Major mailbox providers like Yahoo and Google require senders to have valid rDNS.
- FCrDNS Importance: FCrDNS (Forward Confirmed Reverse DNS) strengthens authentication by ensuring a reciprocal relationship between domain and IP.
Key considerations
- Proper Configuration: Ensure rDNS records are correctly configured to map the IP address to the sending domain.
- Reputation Monitoring: Maintain a positive sender reputation by adhering to email best practices, including valid rDNS.
- FCrDNS Implementation: Consider implementing FCrDNS to further enhance authentication and trustworthiness.
- ISP Requirements: Be aware of specific requirements and guidelines from various ISPs regarding rDNS.
- Legitimate Traffic Source: Having valid rDNS signals that the server is a legitimate source of traffic.
- A to B to A loop: Confirm reverse DNS is set up such that Domain points to IP (via A record), IP points to domain (via PTR record).
What email marketers say
10 marketer opinions
Reverse DNS (rDNS) is crucial for email deliverability because it verifies that the IP address sending email is authorized to do so for the domain it claims to represent. This validation process involves confirming the IP-to-domain relationship, establishing credibility with ISPs, preventing spoofing, and improving sender reputation. Properly configured rDNS records help ensure that receiving mail servers recognize the sending server as legitimate, which reduces the likelihood of emails being marked as spam and improves overall email delivery rates.
Key opinions
- Authentication: rDNS confirms the association between the sending IP address and the domain, proving authorization.
- Deliverability Boost: Correctly configured rDNS improves email deliverability by ensuring mail servers recognize the sender as legitimate.
- Trust Establishment: rDNS helps build trust with ISPs and recipient servers by verifying sender authenticity.
- Spam Prevention: rDNS aids in preventing spoofing and reduces the likelihood of emails being flagged as spam.
Key considerations
- Configuration: Ensure rDNS is correctly configured to match the domain with the sending IP address.
- Reputation Impact: Implement rDNS to enhance sender reputation and improve the chances of successful email delivery.
- Verification Process: Understand that rDNS provides a verification mechanism for email servers to assess sender legitimacy.
- A to B to A Loop: Check that Domain points to IP (via A record), IP points to domain (via PTR record) - if you end up at the same place you started after both lookups, you're good
Marketer view
Email marketer from WebHostingTalk Forum says reverse DNS is important because it provides a crucial check for email servers to ensure that the incoming mail is indeed from a legitimate source, which helps in filtering out spam.
6 Dec 2024 - WebHostingTalk Forum
Marketer view
Email marketer from SMTP2GO shares that reverse DNS validates the association between the sending IP address and domain, preventing spoofing and ensuring mail servers recognize your mail as legitimate.
15 Jul 2023 - SMTP2GO
What the experts say
4 expert opinions
Reverse DNS (rDNS), particularly Forward Confirmed Reverse DNS (FCrDNS), plays a vital role in email deliverability by allowing recipient mail servers to verify the authenticity of the sending server. It confirms the IP address is associated with the sending domain, proving domain and IP owners are cooperating and indicating a legitimate traffic source. Major mailbox providers like Yahoo and Google require valid rDNS. By establishing this trust, rDNS and FCrDNS help improve deliverability rates and prevent emails from being marked as spam.
Key opinions
- Authentication: rDNS helps verify the authenticity of the sending server to recipient mail servers.
- FCrDNS Importance: FCrDNS confirms the relationship between the domain and IP address, proving permission to send.
- Deliverability Improvement: Valid rDNS and FCrDNS contribute to improved email deliverability rates.
- Industry Requirement: Major mailbox providers like Yahoo and Google require valid rDNS for all senders.
Key considerations
- Proper Configuration: Ensure a valid reverse DNS record is set up to associate the IP address with the sending domain.
- FCrDNS Verification: Understand that FCrDNS verifies the relationship between the domain and IP address for added legitimacy.
- Reputation Enhancement: Implement rDNS to build trust with mailbox providers and improve sender reputation.
- Legitimate Traffic Source: Having valid rDNS signals that the server is a legitimate source of traffic.
Expert view
Expert from Word to the Wise responds that FCrDNS (Forward Confirmed Reverse DNS) is used by mailbox providers to verify a relationship between the domain and IP address, confirming the IP has permission to send for the domain which helps improve email deliverability.
7 Aug 2021 - Word to the Wise
Expert view
Expert from Email Geeks shares that reverse DNS lets you take an IP address and map it to a hostname. FCrDNS lets you demonstrate that a hostname and an IP address “match”, which lets you map hostname-based reputation to IP-based reputation. It proves domain and IP owners are cooperating, indicating a legitimate traffic source. Mailbox providers prefer mail from IPs with valid reverse DNS.
18 Feb 2022 - Email Geeks
What the documentation says
5 technical articles
Reverse DNS (rDNS) is essential for email sending because it verifies the legitimacy of the sending server by ensuring the IP address is associated with the domain from which the email originates. This verification process helps build trust with receiving mail servers, improves email delivery rates, and prevents emails from being flagged as spam. rDNS enables mail servers to perform a check on the IP address against the domain, confirming the sender's identity and aiding in sender authentication.
Key findings
- IP Association: rDNS ensures that the IP address is associated with the sending domain.
- Trust Building: It builds trust with receiving mail servers.
- Deliverability Improvement: rDNS improves email delivery rates.
- Spam Prevention: It helps prevent emails from being flagged as spam.
- Authentication Aid: rDNS aids in sender authentication.
Key considerations
- Proper Setup: Ensure that rDNS is correctly configured for your sending IP address and domain.
- Domain Matching: Verify that the rDNS record matches the domain from which emails are sent.
- Verification Check: Understand that receiving mail servers use rDNS to perform a verification check.
- Legitimacy Assurance: Implement rDNS to assure receiving servers of your email's legitimacy.
Technical article
Documentation from Microsoft Learn explains that reverse DNS ensures that the IP address is associated with the sending domain, building trust and improving email delivery rates by verifying the sender's identity.
18 Aug 2022 - Microsoft Learn
Technical article
Documentation from AWS Documentation explains that reverse DNS records are crucial for verifying that the email server is legitimate, preventing it from being flagged as spam and ensuring better delivery rates.
14 Jun 2025 - AWS Documentation
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 a full circle reverse DNS check work?
How important is it for reverse DNS to match SMTP banner for email deliverability?
