Summary
The consensus from experts, marketers, and technical documentation is that shared rDNS for SaaS platforms is not inherently problematic if managed correctly. A properly configured rDNS is essential for verifying the IP address's association with a legitimate sending domain, building trust with ISPs, and improving email deliverability. However, the ultimate success hinges on maintaining a strong IP and domain reputation, achieved through diligent management of shared IPs, preventing abuse, and ensuring clients adhere to email best practices. rDNS alone cannot compensate for a poor IP or domain reputation. Equally important is implementing proper email authentication (SPF, DKIM, DMARC) and ensuring the PTR record points back to the corresponding A record. While modern filters are improving in their ability to differentiate senders on shared platforms, consistent monitoring, management, and enforcement of compliance policies are crucial for long-term deliverability success.
Key findings
- rDNS Validates Identity: rDNS verifies that the IP address is associated with a legitimate sending domain, enhancing credibility.
- Reputation Overrides rDNS: Strong IP and domain reputation are paramount; rDNS alone cannot overcome a poor reputation.
- Authentication is Crucial: SPF, DKIM, and DMARC are essential complements to rDNS, improving deliverability and sender authentication.
- PTR Record Alignment: The PTR record must point back to the corresponding A record for successful reverse DNS lookups.
- Shared IPs Are Risky: Shared IPs can negatively impact deliverability if not diligently managed to prevent abuse.
- ISPs Check rDNS: ISPs use rDNS as one factor when deciding whether to accept email.
Key considerations
- Manage IP Reputation: Proactively monitor and manage IP reputation to identify and address deliverability issues promptly.
- Enforce Compliance: Implement and enforce strict compliance policies to prevent spam and maintain a positive sending reputation.
- Client Best Practices: Provide guidance and oversight to clients to ensure they adhere to email best practices and avoid negatively impacting deliverability.
- Proper Configuration: Ensure that rDNS is correctly configured with the PTR record pointing back to the A record.
- Email Authentication: Implement a comprehensive email authentication strategy using SPF, DKIM, and DMARC.
- Monitor Deliverability: Continuously monitor email deliverability metrics to identify and address any emerging issues.
- IP Warm-up: Warm up sending IPs to build a positive reputation with email providers over time.
What email marketers say
9 marketer opinions
Shared rDNS for SaaS platforms sending emails can be problematic, primarily due to the potential for shared IP addresses to impact deliverability. Properly configured rDNS helps build trust with ISPs by verifying that the IP address is associated with a legitimate sending domain. However, its effectiveness hinges on the SaaS platform's ability to manage the reputation of its shared IPs diligently, preventing abuse and maintaining good sending practices. Proper authentication, including SPF, DKIM, and DMARC, is essential to mitigate deliverability issues.
Key opinions
- rDNS Verification: rDNS verifies the association between an IP address and a legitimate sending domain, improving email deliverability.
- Shared IP Impact: Shared IP addresses can affect deliverability, emphasizing the importance of managing IP reputation.
- Authentication Importance: Proper authentication (SPF, DKIM, DMARC) is crucial when using shared IPs to ensure deliverability.
- PTR Record: The PTR record is checked during a reverse DNS lookup and adds credibility if it resolves back to the sending domain.
Key considerations
- IP Reputation: SaaS platforms must diligently manage the reputation of their shared IPs to prevent abuse and maintain good sending practices.
- Authentication: Implement proper email authentication (SPF, DKIM, DMARC) to enhance credibility and mitigate deliverability issues.
- rDNS Configuration: Ensure that the mail server's IP address has a corresponding rDNS record that points to the domain.
- Monitoring and Management: Continuously monitor and manage IP reputation to address any deliverability issues promptly.
Marketer view
Email marketer from SparkPost shares that Reverse DNS (rDNS) records point IP addresses to domain names, and can prevent IP addresses that are associated with spammers from sending mail, and improve deliverability.
3 Jun 2024 - SparkPost
Marketer view
Email marketer from Neil Patel explains that while shared IP addresses can impact deliverability, a properly configured rDNS that matches the sending domain helps build trust with ISPs. It suggests having dedicated IPs if sending large volumes or experiencing deliverability issues.
25 Mar 2023 - Neil Patel
What the experts say
3 expert opinions
Experts agree that shared rDNS for SaaS platforms sending emails on behalf of clients can be acceptable if certain conditions are met. The critical factor is maintaining a strong IP and domain reputation. While a properly configured rDNS helps build trust and establish credibility, it's not a guaranteed solution. If the SaaS platform allows spammers, fails to enforce compliance, or doesn't ensure clients follow best practices, a shared rDNS won't overcome the negative impact of a poor IP or domain reputation. Modern filters are increasingly capable of separating different customers on a single platform, but vigilant management remains essential.
Key opinions
- Shared rDNS Can Be OK: Shared rDNS isn't inherently problematic if compliance and reputation are well-managed.
- Reputation is Key: Strong IP and domain reputation are essential for deliverability, outweighing the benefits of rDNS alone.
- Client Compliance: SaaS platforms must ensure clients adhere to best practices to avoid negatively impacting the overall reputation.
- Improved Filtering: Modern email filters are better at distinguishing between senders on the same platform.
Key considerations
- Compliance Practices: Implement and enforce strict compliance practices to prevent spam and maintain a positive reputation.
- IP/Domain Reputation: Actively monitor and manage IP and domain reputation, addressing issues promptly.
- Client Management: Provide guidance and oversight to clients to ensure they follow email best practices.
- rDNS Configuration: Ensure rDNS is properly configured but recognize it's just one piece of the deliverability puzzle.
Expert view
Expert from Spam Resource emphasizes the importance of IP reputation and how shared IPs can be problematic if not managed correctly. Proper rDNS configuration helps establish trust, but a poor IP reputation can negate its benefits when a SaaS platform uses shared infrastructure.
7 Apr 2022 - Spam Resource
Expert view
Expert from Word to the Wise explains that domain reputation is critical for deliverability, and rDNS is a factor in establishing credibility. For SaaS platforms, ensuring clients follow best practices is essential, as negative actions can impact the overall domain reputation, even with proper rDNS.
25 Feb 2025 - Word to the Wise
What the documentation says
4 technical articles
Technical documentation from RFC Editor, Microsoft, Google, and AWS consistently highlights the importance of rDNS records (PTR records) for email deliverability. Proper configuration, including ensuring the PTR record points back to the corresponding A record, is crucial to prevent reverse DNS lookups from failing and negatively impacting mail server reputation. Furthermore, these documents emphasize that rDNS works in conjunction with other email authentication methods like SPF, DKIM, and DMARC to build a positive reputation with ISPs and improve overall deliverability, especially when sending emails on behalf of other domains.
Key findings
- PTR Record Importance: PTR records (reverse DNS) must point back to the corresponding A record for proper function.
- Positive Reputation: A correct rDNS record helps build a positive reputation with email services.
- Email Authentication: rDNS is most effective when used in conjunction with SPF, DKIM, and DMARC.
- Improved Deliverability: Setting up rDNS improves email deliverability as ISPs consider rDNS records for email acceptance.
Key considerations
- Proper Configuration: Ensure the PTR record is correctly configured to point back to the A record.
- Holistic Approach: Implement a comprehensive email authentication strategy including SPF, DKIM, and DMARC in addition to rDNS.
- Reputation Management: Monitor and maintain a positive sending IP reputation.
- IP Warm-up: Keep your sending IP warm to establish trust with ISPs.
Technical article
Documentation from AWS shares that setting up rDNS for your sending IP addresses can help improve email deliverability because some ISPs consider rDNS records when determining whether to accept emails.
1 Jan 2022 - AWS
Technical article
Documentation from RFC Editor explains that a PTR record (reverse DNS) should point back to the corresponding A record. Ensuring this configuration prevents reverse DNS lookups from failing, which can affect mail server reputation.
11 Apr 2022 - RFC Editor
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