What causes an IP to be listed on the Spamhaus Block List (SBL) and how can it be resolved?

Summary

An IP address ends up on the Spamhaus Block List (SBL) due to various factors, including spamming activities, insecure web forms leading to listbombing, high spam complaint rates, sending emails to invalid addresses, compromised accounts, spam traps, and malware infections. To prevent blacklisting, it's crucial to implement strict email authentication protocols (SPF, DKIM, DMARC), maintain clean and engaged email lists through practices like double opt-in and regular cleaning, monitor sender reputation, promptly address abuse complaints, and send valuable content while respecting unsubscribe requests. Shared IPs pose a higher risk. To resolve being listed, identify the specific blacklist, understand its removal policy, follow the delisting process (often involving a form and proof of issue resolution), and verify that the underlying issues have been addressed. Tools are available to check blacklisting status. Feedback loops, list hygiene, and engaging content are essential for maintaining IP health. Consider dedicated IPs for high volume sending.

Key findings

  • SBL Listing Causes: Spamming, insecure web forms, high spam complaints, invalid addresses, compromised accounts, spam traps, and malware infections can lead to SBL listing.
  • Authentication Importance: Proper implementation of SPF, DKIM, and DMARC is crucial for establishing legitimacy and preventing emails from being flagged as spam.
  • List Management: Maintaining clean and engaged email lists through double opt-in and regular cleaning is essential.
  • Shared IP Risk: Using shared IPs increases the risk of blacklisting due to the actions of other users on the same IP.
  • Reputation Monitoring: Regularly monitoring sender reputation is vital for identifying and addressing potential deliverability issues.

Key considerations

  • Delisting Process: Understand and follow the specific delisting process for each blacklist, often requiring a form and proof of issue resolution.
  • Feedback Loops: Monitor feedback loops to identify and address spam complaints and other deliverability issues.
  • Proactive Measures: Take proactive measures to improve IP reputation, such as sending valuable content and engaging with subscribers.
  • Dedicated IP: Consider using a dedicated IP address, especially for high-volume sending, to maintain better control over reputation.
  • Secure Web Forms: Ensure web forms are secure to prevent spammers from abusing them and causing listbombing issues.

What email marketers say
13Marketer opinions

An IP address can be listed on the Spamhaus Block List (SBL) for various reasons, including insecure web forms exploited by spammers, high spam complaint rates, sending to invalid email addresses, compromised accounts, spam traps, and malware infections. Resolution involves identifying the blacklist, understanding their removal policy, authenticating your email (SPF, DKIM, DMARC), maintaining clean and engaged email lists, monitoring your sender reputation, respecting unsubscribe requests, avoiding spam trigger words, and promptly addressing any complaints. Regularly monitor your sending reputation and infrastructure. Confirmation of Opt-In can help, also.

Key opinions

  • Causes for Listing: Insecure web forms, spam complaints, invalid addresses, compromised accounts, spam traps, and malware can lead to SBL listing.
  • Importance of Authentication: Proper email authentication (SPF, DKIM, DMARC) is crucial for establishing legitimacy and preventing spam flagging.
  • List Hygiene: Maintaining clean, engaged email lists and avoiding spam traps are essential.
  • Shared IPs: Using a shared IP can increase blacklisting risk due to others' actions.
  • Monitoring: Regular monitoring of sender reputation and infrastructure is vital.

Key considerations

  • Delisting Process: Understand the specific blacklist's removal policy and follow their delisting process, often requiring a form and proof of issue resolution.
  • Sender Reputation: Consistently send valuable content, respect unsubscribe requests, and engage with your audience to maintain a good sender reputation.
  • Proactive Measures: Improve IP reputation by sending emails to engaged subscribers and consistently monitoring your sender score.
  • Complaint Rates: Consistently low complaint rates and high engagement improve reputation and reduce the likelihood of blacklisting.
  • Permission Based: Avoid spam traps, practice good list hygiene, use double opt-in, and regularly cleaning your list by removing inactive subscribers. Always get permission before sending emails.
Marketer view

Marketer from Email Geeks explains that the address itself might not be dangerous; plenty of them will be regular people's real addresses who did not sign up and are victims of a bad actor + your insecure form

August 2021 - Email Geeks
Marketer view

Marketer from Email Geeks shares that the reason in the listings..."Spammers have abused an insecure webform sometime in the past, and used the victim's email address. As a result, the victim is being "listbombed" with transactional messages and bulk email campaigns. For additional information, please see this link: <https://www.spamhaus.org/news/article/734/subscription-bombing-coi-captcha-and-the-next-generation-of-mail-bombs>"

November 2024 - Email Geeks

What the experts say
3Expert opinions

Maintaining a healthy IP reputation is crucial to avoid being listed on the Spamhaus Block List (SBL). Key factors influencing IP reputation include sending volume, spam complaint rates, and engagement metrics. Monitoring feedback loops, practicing proper list hygiene, and consistently achieving low complaint rates contribute to a positive reputation. You can check your IP's status on blocklists via online lookup tools, which often provide guidance on remediation.

Key opinions

  • IP Reputation Factors: Sending volume, spam complaints, and engagement significantly influence IP reputation.
  • Importance of Monitoring: Monitoring feedback loops and checking blocklist status are essential for maintaining IP health.
  • List Hygiene: Proper list hygiene is critical for preventing blacklisting.

Key considerations

  • Complaint Rates: Strive for consistently low spam complaint rates.
  • Engagement Metrics: Focus on improving engagement metrics to boost your reputation.
  • Remediation: If blacklisted, use lookup tools to get tailored advice and take action.
Expert view

Expert from Word to the Wise explains that steps to maintaining IP health include: Monitoring feedback loops, keeping low complaint rates, and ensuring proper list hygiene.

September 2022 - Word to the Wise
Expert view

Expert from Word to the Wise, Laura Atkins, shares that IP reputation is influenced by factors such as sending volume, spam complaints, and engagement metrics. Consistently low complaint rates and high engagement improve reputation and reduce the likelihood of blacklisting.

May 2024 - Word to the Wise

What the documentation says
6Technical articles

IP addresses are listed on the Spamhaus Block List (SBL) for sending spam, hosting spambots, or participating in spam networks. Preventing blacklisting involves strict email authentication (SPF, DKIM, DMARC), monitoring sender reputation, and maintaining clean email lists. If blocked, identify the reason from bounce messages, follow the blocklist provider's remediation steps (often involving a delisting request), and ensure issues are resolved. SPF helps prevent address forging, and DMARC builds upon SPF/DKIM to instruct mail servers on handling failed authentication attempts, reducing phishing and spoofing.

Key findings

  • Reasons for SBL Listing: Sending spam, hosting spambots, or participating in spam networks leads to SBL listing.
  • Prevention Methods: Strict email authentication (SPF, DKIM, DMARC), sender reputation monitoring, and clean email lists are key to prevention.
  • Remediation Steps: Identify the reason for the block and follow the blocklist provider's specific delisting process.
  • SPF Functionality: SPF helps prevent email address forging by verifying authorized senders.
  • DMARC Enhancement: DMARC builds upon SPF and DKIM to protect against phishing and spoofing by guiding mail servers on handling authentication failures.

Key considerations

  • Authentication Implementation: Implement and regularly review SPF, DKIM, and DMARC configurations to ensure proper authentication.
  • Reputation Monitoring: Consistently monitor your sender reputation using tools like Sender Score to identify and address potential issues.
  • Delisting Process Adherence: Thoroughly understand and follow the specific delisting instructions for each blocklist provider.
  • Address Abuse Complaints: Promptly investigate and resolve any abuse complaints to prevent future blacklistings.
Technical article

Documentation from Dmarc.org explains that DMARC builds upon SPF and DKIM to provide a mechanism for email senders to indicate that their messages are protected by these authentication methods, and instructs receiving mail servers on what to do if authentication fails, helping to reduce phishing and spoofing.

May 2022 - Dmarc.org
Technical article

Documentation from Digital Ocean explains that to prevent IP blacklisting, implement strict email authentication protocols (SPF, DKIM, DMARC), monitor your sending reputation using tools like Sender Score, maintain clean and engaged email lists, and promptly address any abuse complaints.

September 2022 - Digital Ocean