How does missing or different reverse DNS (rDNS) impact email deliverability, and when is a dedicated IP address needed?

Summary

The consensus is that reverse DNS (rDNS) significantly impacts email deliverability, with most sources emphasizing the importance of a correct rDNS record for authentication and sender reputation. A missing or incorrect rDNS can lead to emails being flagged as spam, rejected by ISPs, or negatively impacting inbox placement, especially with enterprise filters. Different rDNS across a range isn't necessarily a problem if those IPs aren't actively sending. Regarding dedicated IPs, the need arises when senders require more control over their reputation, send a high volume (generally above 5,000 emails/day or 50,000/month), or seek isolation from other senders. However, success with a dedicated IP hinges on maintaining a clean email list and consistent sending practices. Some suggest that if you can't maintain a good sender score, a shared IP with a reputable ESP might be preferable. The decision depends on individual circumstances and priorities, and not assuming all IPs in a range are used for sending mail. A minority opinion suggests rDNS is less critical if the IP doesn't point nowhere, but this is outweighed by the majority view emphasizing its importance.

Key findings

  • rDNS Authentication: A correct rDNS record is a crucial part of email authentication, verifying the sending server's identity.
  • rDNS Impact on Deliverability: Missing or incorrect rDNS can negatively impact deliverability, leading to spam flagging or rejection by ISPs.
  • Dedicated IP Need: A dedicated IP is needed for high-volume senders, or those requiring more control over their sending reputation.
  • Dedicated IP Requires Maintenance: Success with a dedicated IP depends on maintaining a clean email list and consistent sending practices.
  • Shared IP Alternative: A shared IP with a reputable ESP might be a better option if you cannot maintain a high sender score.
  • Not all IP's are used for Sending: Don't assume all IP's in a range are used for sending mail, so rDNS is most important for used IP addresses

Key considerations

  • Verify rDNS Records: Ensure your rDNS records are correctly configured and match your sending domain.
  • Assess Sending Volume: Evaluate your sending volume to determine if a dedicated IP is necessary.
  • Manage Sender Reputation: If opting for a dedicated IP, be prepared to manage and monitor your sending reputation.
  • Practice List Hygiene: Maintain a clean email list to avoid deliverability problems, especially with a dedicated IP.
  • Understand Enterprise Filters: Be aware that enterprise filters are more strict about missing or incorrect rDNS records, or other related practices.
  • Evaluate Reputation Needs: Determine if you require full control over your sending reputation before investing in a dedicated IP.
  • Understand Requirements: Yahoo and Google require round trip DNS, so it's best to follow these

What email marketers say
11Marketer opinions

The impact of missing or incorrect reverse DNS (rDNS) on email deliverability varies, with some experts considering it crucial for sender reputation and others downplaying its importance if the IP doesn't point nowhere. Correct rDNS records help ISPs verify the legitimacy of emails, improving deliverability and open rates. A dedicated IP address is needed when senders require more control over their reputation, send high volumes (50,000+ per month), or want to isolate their sending from others. However, maintaining a clean email list and consistent sending practices are essential for a dedicated IP's success; otherwise, a shared IP with a reputable ESP may be better.

Key opinions

  • rDNS Impact: Correct rDNS records are generally crucial for building a good sender reputation and improving email deliverability by confirming legitimacy to ISPs.
  • rDNS Negligence: Missing or poor rDNS setup can lead to emails being marked as spam and damaging the sender's reputation.
  • Dedicated IP Volume: A dedicated IP address is often recommended for high-volume senders (50,000+ emails per month) needing greater control over their reputation.
  • Dedicated IP Reputation: Maintaining a clean email list and consistent sending practices are essential for a dedicated IP's success.
  • Dedicated IP Alternatives: If maintaining a high sender score isn't possible, a shared IP with a reputable ESP might be a better option than a dedicated IP.

Key considerations

  • rDNS Setup: Ensure your rDNS record matches your sending domain to prove the legitimacy of your emails.
  • Sending Volume: Assess your sending volume to determine if a dedicated IP is necessary or if a shared IP suffices.
  • Reputation Management: Evaluate your ability to manage and monitor your sending reputation before switching to a dedicated IP.
  • List Hygiene: Maintain a clean email list to avoid deliverability issues, especially when using a dedicated IP.
  • Control Needs: Consider your need for control over your sending environment when deciding between a dedicated and shared IP.
Marketer view

Email marketer from Mailjet shares that having a correct rDNS record is crucial for building a good sender reputation and improving email deliverability. An rDNS record that matches your sending domain helps ISPs confirm the legitimacy of your emails.

September 2022 - Mailjet
Marketer view

Email marketer from Reddit shares that getting a dedicated IP depends less on volume and more on reputation management. They suggest a dedicated IP is good if the sender can maintain a high sender score, otherwise, a shared IP with a reputable ESP is better.

January 2022 - Reddit
Marketer view

Email marketer from Email Geeks advises to exclude concerns about rDNS when evaluating reasons for needing a dedicated IP address. As long as the IP doesn’t point nowhere, it should have little to do with deliverability. It is unlikely to rock the boat if you are not a perfectionist where Google does not expect perfection. States there's no upside to switching to a dedicated IP address because of anything discussed in this thread. Volume is about ~4Ok/month which is well within the scope of shared IP addresses.

June 2023 - Email Geeks
Marketer view

Email marketer from Email Marketing Forum discusses that problems sending emails to particular email providers was solved when they corrected their rDNS record to match their sending domain. They share that their email open rate went up significantly

October 2021 - Email Marketing Forum
Marketer view

Email marketer from DigitalOcean details the need to set up rDNS for email servers. Reverse DNS helps receiving servers verify that the sending server is authorized to send emails for a particular domain, and without it, emails may be flagged as spam or rejected outright.

May 2021 - DigitalOcean
Marketer view

Email marketer from Constant Contact explains that poor RDNS setup can lead to emails being marked as spam and a damaged sender reputation. Ensuring your RDNS record matches your domain is key to proving the legitimacy of your emails.

November 2023 - Constant Contact
Marketer view

Email marketer from ZeroBounce advises that a dedicated IP is beneficial for senders who can maintain a consistent sending volume and a clean email list. They state that without proper list hygiene, a dedicated IP can quickly become a liability.

September 2021 - ZeroBounce
Marketer view

Email marketer from SendPulse explains that a dedicated IP address is needed when sending a high volume of emails (50,000+ per month) or when wanting more control over sender reputation. They share that consistent sending practices and careful list management are essential for maintaining a good reputation on a dedicated IP.

March 2025 - SendPulse
Marketer view

Email marketer from SparkPost explains that if an IP address lacks a Reverse DNS (rDNS) record, receiving mail servers are more likely to consider emails from that IP as spam. A missing rDNS record makes it difficult to verify the legitimacy of the sending server and can negatively impact sender reputation.

November 2022 - SparkPost
Marketer view

Email marketer from ReturnPath (now Validity) shares that a dedicated IP is beneficial for senders who need more control over their reputation and want to isolate their sending from the activities of other senders on a shared IP.

April 2024 - ReturnPath
Marketer view

Email marketer from Litmus emphasizes the need for a dedicated IP address when aiming for greater control over sender reputation. A dedicated IP allows you to manage and monitor your sending practices closely, which is essential for maintaining a positive sender score.

November 2022 - Litmus

What the experts say
4Expert opinions

Experts agree that reverse DNS (rDNS) plays a significant role in email deliverability. Missing or incorrect rDNS records can negatively impact delivery, especially for enterprise filters and may cause emails to be rejected or sent to spam. While some may downplay rDNS importance for IP ranges not actively sending mail, a correct rDNS record is generally seen as a crucial part of email authentication. A dedicated IP address is recommended when senders need more control over their reputation and sending volume.

Key opinions

  • rDNS Impact on Deliverability: Missing or incorrect rDNS records can negatively affect email delivery rates, especially for enterprise filters, potentially leading to emails being rejected or marked as spam.
  • Yahoo and Google Requirements: Yahoo and Google require round trip DNS, emphasizing the importance of rDNS for their email services.
  • rDNS and Sending IPs: rDNS matters most for IPs actively sending mail; it's less relevant for reserved IPs in a range that are not in use.
  • rDNS as Authentication: A correct rDNS record is crucial for email authentication, making it a key factor for ISPs in accepting or rejecting emails.
  • Dedicated IP Control: A dedicated IP is recommended when senders need greater control over their reputation and sending volume.

Key considerations

  • Check rDNS Configuration: Verify that rDNS records are correctly configured, especially for IPs actively sending email.
  • Enterprise Filters: Be aware that enterprise filters may be more strict about missing or incorrect rDNS.
  • Control Over Reputation: Assess your need for control over your sending reputation when considering a dedicated IP.
  • Understand ISP Requirements: Understand that some ISPs may reject email from IPs with missing or incorrect rDNS.
  • IP Range Usage: Don't assume all IPs in a range are used for sending mail; focus on those actively sending.
Expert view

Expert from Email Geeks advises not to assume that all IPs in a range are used for sending mail. States that there are a lot of pools that aren’t the whole /24. They state that rDNS only matters if mail is seen from the IP.

March 2022 - Email Geeks
Expert view

Expert from Word to the Wise explains the importance of reverse DNS for email deliverability, stating that many ISPs use it as a factor in determining whether to accept or reject an email. They suggest that a missing or incorrect RDNS record can severely affect inbox placement.

April 2021 - Word to the Wise
Expert view

Expert from Spam Resource explains that a correct reverse DNS (rDNS) record is a crucial part of email authentication and that failing to have a valid, matching rDNS record will significantly reduce email deliverability. A dedicated IP address might be considered when a sender requires full control over their sending reputation and volume.

May 2023 - Spam Resource
Expert view

Expert from Email Geeks explains that missing reverse DNS may impact delivery, especially for enterprise filters. They clarify that Yahoo and Google require round trip DNS. Different reverse DNS across a range isn’t a problem in itself.

November 2024 - Email Geeks

What the documentation says
4Technical articles

Official documentation consistently highlights the importance of reverse DNS (rDNS) for email deliverability. Missing or incorrect rDNS records can lead to emails being flagged as spam or rejected outright, as many servers use rDNS for identity verification. Google recommends a dedicated IP for senders exceeding 5,000 emails per day, emphasizing the need for reputation management at that volume. Proper rDNS configuration is deemed a basic requirement for authentication by Postfix.

Key findings

  • rDNS Impact: Missing or incorrect rDNS negatively impacts email deliverability.
  • rDNS for Verification: Email servers use rDNS to verify the sending server's identity.
  • Spam Flagging: Emails lacking proper rDNS may be flagged as spam.
  • Dedicated IP Recommendation: Google recommends a dedicated IP for sending over 5,000 emails per day.
  • rDNS for Authentication: Proper rDNS is a basic requirement for email authentication.

Key considerations

  • rDNS Configuration: Ensure rDNS records are correct and match the sending IP address.
  • Dedicated IP Threshold: Consider a dedicated IP if sending over 5,000 emails daily.
  • Reputation Management: Manage and monitor IP reputation when using a dedicated IP.
  • Authentication Standard: Implement proper rDNS configuration for email authentication.
Technical article

Documentation from Microsoft Learn explains that a missing or incorrect Reverse DNS (rDNS) record can negatively impact email deliverability as many email servers use rDNS to verify the identity of the sending server. If the rDNS record doesn't match the sending IP address, the email might be flagged as spam.

February 2022 - Microsoft Learn
Technical article

Documentation from Google Workspace Admin Help shares that Google recommends using a dedicated IP if sending over 5,000 emails per day. They specify that this volume warrants the investment in managing and monitoring your own IP reputation to ensure consistent deliverability to Gmail users.

May 2024 - Google Workspace Admin Help
Technical article

Documentation from RFC Editor details standard DNS configuration, emphasizing the importance of PTR records (rDNS) for reverse lookups. It explains that failing to have a proper rDNS record can lead to email being rejected by receiving mail servers that perform reverse DNS verification.

May 2022 - RFC Editor
Technical article

Documentation from Postfix.org highlights that proper rDNS configuration is a basic requirement for email authentication and deliverability. They state that servers without correctly configured rDNS are often viewed as less trustworthy and may face delivery issues.

August 2021 - Postfix.org