How do SURBL listings affect Gmail deliverability and inbox placement?

Summary

SURBL (Spam URI Realtime Blocklist) listings can significantly harm email deliverability and inbox placement in Gmail. These lists identify domains and URLs that have appeared in spam messages, indicating an association with spam, phishing, or other malicious activities. Email providers, including Gmail, use SURBLs as one of the many data points to filter unwanted emails, leading to messages being blocked, sent to the spam folder, or experiencing reduced inbox placement. The impact of a SURBL listing can be immediate, causing drops in open rates and engagement. It is important to monitor domain reputation, address the underlying issues that led to the listing, and follow delisting procedures to restore normal deliverability. Additionally, other blocklists like BRBL and URIBL can similarly impact deliverability, making proactive reputation management vital.

Key findings

  • Deliverability Impact: SURBL listings negatively impact email deliverability and inbox placement in Gmail.
  • Spam Identification: SURBLs identify domains and URLs that have appeared in spam messages.
  • Filtering Mechanism: Email providers use SURBLs to filter unwanted emails based on their association with spam, phishing, or other malicious activities.
  • Data Point Consideration: SURBLs are used as one data point among many by email providers to determine message filtering.
  • Underlying Causes: The reasons for a SURBL listing, such as poor sending practices, also independently affect deliverability.
  • Immediate Impact: SURBL listings can have an immediate and significant negative impact on email engagement metrics.
  • Recovery Possible: Delisting from SURBLs and addressing underlying sending issues can restore deliverability.
  • Similar Blocklists: Other blocklists like BRBL and URIBL can similarly affect deliverability.

Key considerations

  • Domain Monitoring: Continuously monitor domain and URL reputation to identify and address SURBL listings quickly.
  • Sending Practices: Implement and maintain email sending best practices to prevent SURBL listings.
  • Delisting Process: Familiarize yourself with and follow the delisting procedures for each SURBL.
  • Reputation Management: Actively manage sender reputation to minimize the risk of being added to blocklists.
  • Holistic Approach: Acknowledge that deliverability is multifactorial and requires a holistic approach to email sending practices.

What email marketers say
12Marketer opinions

SURBL (Spam URI Realtime Blocklist) listings can negatively affect Gmail deliverability and inbox placement. If a domain or IP address appears on a SURBL, it signals an association with spam or malicious activity. While not all email providers weigh SURBLs equally, Gmail, among others, uses them as one data point to determine whether to block, filter to spam, or deliver emails. The impact can range from reduced inbox placement to complete blocking. The specific practices leading to the SURBL listing are often the root cause of deliverability issues. Even minor blacklistings can coincide with Gmail bulking, where Gmail picks up on behavior patterns that cause the listings. Removing the domain from the SURBL and addressing the underlying issues may return deliverability to normal.

Key opinions

  • Negative Impact: SURBL listings generally lead to reduced email deliverability and poorer inbox placement in Gmail.
  • Spam Signal: A SURBL listing indicates that a domain or IP has been associated with spam or malicious activities.
  • Data Point: Email providers like Gmail use SURBLs as one data point, among many, to determine email filtering decisions.
  • Root Cause: The practices causing the SURBL listing often contribute to deliverability issues independently.
  • Bulking Correlation: Minor blacklistings can coincide with Gmail's tendency to bulk certain emails, due to similar behavioral patterns.
  • Recovery Possible: Removing a domain from SURBL and rectifying the underlying issues can restore normal deliverability.

Key considerations

  • Monitoring: Continuously monitor domain reputation and promptly address any SURBL listings.
  • Underlying Practices: Identify and correct the sending practices that led to the SURBL listing to prevent future occurrences.
  • Holistic Approach: Deliverability is multifactorial; SURBLs are just one aspect. Ensure all sending practices align with best practices.
  • Delisting Process: Understand and follow the specific delisting process for each SURBL.
  • Gmail Variance: Be aware that Gmail's algorithms and their weighting of factors can change over time.
Marketer view

Email marketer from SendPulse explains that being listed on an RBL (which includes SURBLs) can hurt sender reputation and email deliverability. They share that email providers like Gmail use these lists to identify and filter spam.

January 2022 - SendPulse
Marketer view

Email marketer from StackExchange states that SURBLs are used by some (but not all) email providers to help determine if an email is spam. If your domain is listed, your emails are more likely to be marked as spam or blocked entirely, thus affecting deliverability.

November 2023 - StackExchange
Marketer view

Marketer from Email Geeks states that they have seen lots of cases where minor blacklistings coincide with Gmail bulking and that Gmail picks up on the same sort of behavior that causes the blacklistings.

March 2023 - Email Geeks
Marketer view

Marketer from Email Geeks explains the difference between providers using a list to send to spam/block and using a list as *one* data point in a constellation of data points which, taken as a whole, they use to make their delivery determinations. They agree that it's most likely that the practices/issues that got the sender listed on SURBL are the issue, not the listing itself, but it's certainly a data point.

April 2021 - Email Geeks
Marketer view

Email marketer from Mailjet explains that SURBL listings can negatively impact email deliverability. Being listed on a SURBL indicates that your domain or IP address has been associated with spam or malicious activity, which can lead to emails being blocked or sent to spam folders by email providers like Gmail.

May 2023 - Mailjet
Marketer view

Email marketer from Postmark explains that blacklists (including SURBLs) flag IP addresses and domains known for sending spam. They further explain that being listed on a major blacklist can lead to a significant drop in deliverability, with emails being blocked or sent to the spam folder.

November 2021 - Postmark
Marketer view

Email marketer from Litmus explains that inbox placement is a crucial metric, and SURBL listings can negatively impact it. Litmus shares that being listed on a SURBL can result in emails being filtered as spam, leading to lower open rates and decreased engagement.

September 2021 - Litmus
Marketer view

Email marketer from Reddit shares that they experienced a significant drop in email deliverability to Gmail after their domain was listed on a SURBL. After delisting, deliverability returned to normal, suggesting a direct correlation.

March 2021 - Reddit
Marketer view

Marketer from Email Geeks shares their experience of a SURBL listing immediately affecting inbox placement in Gmail. They got delisted, and everything returned to normal.

September 2024 - Email Geeks
Marketer view

Email marketer from EmailToolTester responds that SURBL listings identify domains that appear in spam and can be used by mailbox providers in determining which emails to block or send to the spam folder.

March 2023 - EmailToolTester
Marketer view

Email marketer from GlockApps explains that RBLs like SURBLs are used by ISPs and email providers (like Gmail) to help identify sources of spam. GlockApps shares that if your IP or domain is on a SURBL, your emails are less likely to reach the inbox.

December 2024 - GlockApps
Marketer view

Email marketer from Email Marketing Forum mentions that being on a SURBL can be a significant factor in Gmail's decision to filter emails, especially if other negative signals are present. They recommend monitoring your domain's reputation and promptly addressing any listings.

November 2021 - Email Marketing Forum

What the experts say
2Expert opinions

Appearing in spam can lead to a URL being listed in a URI DNSBL (SURBL), which has detrimental effects on email deliverability. This can cause messages containing the listed URL to be blocked or directed to the spam folder. Being on more blocklists negatively impacts how much email reaches the inbox.

Key opinions

  • SURBL Listing Consequence: URLs found in spam may be listed in a URI DNSBL (SURBL).
  • Deliverability Impact: SURBL listings result in emails being blocked or sent to spam folders.
  • Blocklist Harm: The more blocklists you are on, the less email reaches the inbox.

Key considerations

  • URL Monitoring: Monitor URLs in your email campaigns to prevent them from appearing in spam.
  • Reputation Management: Actively manage your sending reputation to minimize the risk of blocklist inclusion.
  • Content Scrutiny: Carefully review the content of your emails to avoid triggering spam filters and blocklists.
  • Prevention: Proactive steps and prevention measures are most beneficial to help avoid being listed.
Expert view

Expert from Spamresource shares that a URL showing up in spam can lead to being listed in a URI DNSBL (SURBL). They explain that this can have negative consequences for email deliverability, causing messages containing the URL to be blocked or sent to the spam folder.

April 2024 - Spamresource
Expert view

Expert from Word to the Wise (Laura Atkins) discusses that landing on blocking lists is harmful to deliverability. The more lists that block you, the less mail gets delivered to the inbox.

November 2022 - Word to the Wise

What the documentation says
4Technical articles

SURBLs (Spam URI Realtime Blocklists) are lists of websites found in spam messages. Email providers, including Gmail, use these lists to filter unwanted emails. A SURBL listing indicates that a website has been associated with spam, phishing, malware, or abusive content, leading to reduced deliverability. Email providers may block or filter emails containing links to listed websites, sending them to the junk folder. Similar lists, such as the Barracuda Reputation Block List (BRBL), have the same impact.

Key findings

  • SURBL Definition: SURBLs are lists of websites appearing in spam messages.
  • Filtering Mechanism: Email providers use SURBLs to filter unwanted emails.
  • Deliverability Reduction: A SURBL listing reduces email deliverability to Gmail and other providers.
  • Link Association: A SURBL listing indicates a website has been linked to spam, phishing, malware, or abusive content.
  • Blocking or Filtering: Email providers may block or filter emails containing links to listed websites, sending them to the junk folder.
  • Similar Lists: Lists like the Barracuda Reputation Block List (BRBL) have similar impacts on deliverability.

Key considerations

  • Website Monitoring: Monitor your website to ensure it is not associated with spam or malicious content.
  • Content Scrutiny: Review email content to avoid links to websites listed on SURBLs.
  • Reputation Management: Maintain a good sender reputation to minimize the risk of being listed on SURBLs or similar blocklists.
  • Proactive measures: Proactive steps and prevention measures are most beneficial to help avoid being listed.
Technical article

Documentation from MultiRBL shares that being listed on a SURBL indicates that your website has been linked to spam. This can significantly harm your email deliverability, as email providers may block or filter emails containing links to listed websites.

September 2022 - MultiRBL
Technical article

Documentation from URIBL shares that its URI Block Lists can impact email deliverability. It states URIBLs are used to identify spam, phishing, malware, and other abusive content. Email marked with a URIBL hit may be dropped or sent to the junk folder.

April 2024 - URIBL
Technical article

Documentation from BarracudaCentral explains that if you're on the Barracuda Reputation Block List (BRBL) or other similar lists, your email may be blocked or sent to the spam folder by email providers using the BRBL. This highlights the potential impact of blocklists on deliverability.

January 2024 - BarracudaCentral
Technical article

Documentation from Spamhaus explains that SURBLs (Spamhaus URI Realtime Blocklist) are lists of websites that have appeared in spam messages. Email providers use these lists to filter out unwanted emails, and a listing can result in reduced deliverability to Gmail and other providers.

August 2021 - Spamhaus