Why were there sudden Spamhaus IP listings this morning?

Summary

Sudden Spamhaus IP listings can be caused by a variety of factors, including temporary glitches within Spamhaus itself, compromised accounts sending spam, sudden increases in email volume or spam complaints, poor list hygiene leading to high bounce rates, sending unsolicited emails, or misconfigured email authentication settings (SPF, DKIM, DMARC). Additionally, Spamhaus lists IPs involved in sending or supporting spam, including hosting spammed websites. Poor data quality causing bounces and spam traps, non-RFC compliant email practices, and compromised systems contribute to the issue. Resolution requires identifying the cause, requesting delisting, improving sender reputation, implementing strong email authentication, ensuring compliance with anti-spam laws, and monitoring sender reputation.

Key findings

  • Spamhaus Glitches: Temporary glitches within Spamhaus can cause IPs to be briefly listed and then removed.
  • Compromised Accounts: Compromised accounts or malware infections can lead to unauthorized spam sending, triggering listings.
  • List Hygiene: Poor list hygiene practices, such as high bounce rates and spam complaints, contribute to blacklisting.
  • Volume Spikes: Sudden increases in email volume or spam complaints can raise suspicion and lead to listings.
  • Authentication Issues: Improperly configured or missing email authentication (SPF, DKIM, DMARC) can negatively impact sender reputation.
  • Spam Traps: Sending emails to spam trap addresses damages sender reputation.
  • Involvement in Spam: Involvement in sending or supporting spam activities, directly or indirectly, can cause listings.
  • Poor Data Quality: Poor data quality from old or incorrect information, contributes to bounces and spam traps.
  • Non-Compliance: Non-RFC Compliant emails with incorrect information are a key finding.

Key considerations

  • Investigate and Resolve: Identify the root cause of the listing, whether it's a glitch, compromised account, poor list hygiene, technical misconfiguration, or spam activity.
  • Improve Sender Reputation: Implement best practices for email sending, including double opt-in, valuable content, and list segmentation, to improve sender reputation.
  • Monitor Sending Practices: Actively monitor sender reputation, bounce rates, and spam complaints to proactively address potential issues.
  • Ensure Compliance: Ensure that email sending practices comply with anti-spam laws and regulations.
  • Implement Authentication: Implement and properly configure SPF, DKIM, and DMARC to authenticate email and protect against spoofing.
  • Request Delisting: Request delisting from Spamhaus once the underlying issue has been resolved.
  • Remediate Security: Ensure that there is remediation against spam and compromises.
  • Data Quality: Improve data quality, removing incorrect or old information.

What email marketers say
9Marketer opinions

Sudden Spamhaus IP listings are often caused by a variety of factors including: Spamhaus issues that may be temporary, compromised accounts or malware infections leading to spam being sent, sudden spikes in email volume, poor list hygiene resulting in high bounce rates and spam complaints, sending unsolicited emails, and issues with email authentication such as SPF, DKIM, and DMARC. Improving data quality, monitoring sender reputation, and ensuring compliance with anti-spam laws are crucial for preventing and resolving these listings.

Key opinions

  • Compromised Accounts: Compromised accounts and malware infections can lead to unauthorized spam sending, triggering Spamhaus listings.
  • List Hygiene: Poor list hygiene practices, such as high bounce rates and spam complaints, contribute to blacklisting.
  • Email Volume Spikes: Sudden increases in email volume can raise suspicion and lead to temporary or prolonged listings.
  • Authentication Issues: Improperly configured or missing email authentication (SPF, DKIM, DMARC) can negatively impact sender reputation.
  • Spam Traps: Sending emails to spam trap addresses can severely damage sender reputation and result in listings.
  • Data Quality: Poor data quality causes bounces and spam traps.

Key considerations

  • Investigate and Resolve: Identify the root cause of the listing, whether it's a compromised account, poor list hygiene, or technical misconfiguration.
  • Improve Sender Reputation: Implement best practices for email sending, including double opt-in, valuable content, and list segmentation, to improve sender reputation.
  • Monitor Sending Practices: Actively monitor sender reputation, bounce rates, and spam complaints to proactively address potential issues.
  • Ensure Compliance: Ensure that email sending practices comply with anti-spam laws and regulations.
  • Implement Authentication: Implement and properly configure SPF, DKIM, and DMARC to authenticate email and protect against spoofing.
  • Data Quality: Improve data quality, removing incorrect or old information.
Marketer view

Email marketer from Mailjet explains that sudden IP listings and blacklists are sometimes caused by a sudden spike of spam complaints, a increase in spam traps being hit or a sudden increase in volume.

March 2021 - Mailjet
Marketer view

Email marketer from Email Geeks confirms that there was definitely something going on at Spamhaus this morning with many clients listed but quickly removed.

June 2024 - Email Geeks
Marketer view

Email marketer from SendPulse shares that you must identify the reason for the listing which is often caused by poor list hygiene, spam content, or a compromised account. Address the root cause and request delisting. Also, implement strategies to prevent future issues.

October 2024 - SendPulse
Marketer view

Email marketer from Reddit shares that sudden Spamhaus listings can occur due to a variety of reasons, including compromised accounts sending spam, a sudden spike in email volume, or issues with email authentication such as SPF, DKIM, and DMARC.

November 2021 - Reddit
Marketer view

Email marketer from ZeroBounce shares that the best way to get off of a blacklist such as Spamhaus is to improve your sender reputation. Use double opt-ins to ensure people want your emails, make your content useful, segment your lists and warm up your IPs to increase trust and validity of emails.

August 2022 - ZeroBounce
Marketer view

Email marketer from StackOverflow responds that being listed on Spamhaus can result from several issues, such as poor list hygiene leading to high bounce rates and spam complaints, sending unsolicited emails, or having a server with a compromised IP address.

June 2024 - StackOverflow
Marketer view

Email marketer from EmailDudes Forum shares that you should investigate possible malware infections on your server or network, ensure your email sending practices comply with anti-spam laws, and that your sender reputation is actively monitored and maintained.

May 2022 - EmailDudes Forum
Marketer view

Email marketer from Kickbox emphasizes the role of data quality. Poor data quality that is caused by incorrect or old information causes bounces and spam traps. The Kickbox article recommends that to avoid blacklists, you should remove any invalid emails as soon as possible.

February 2023 - Kickbox
Marketer view

Email marketer from GlockApps explains that Spamhaus listings can be triggered by spam traps, high complaint rates, or sending from IPs with poor reputations. Ensuring proper authentication and monitoring your sending reputation is key.

August 2024 - GlockApps

What the experts say
3Expert opinions

Sudden Spamhaus IP listings can stem from various causes, including Spamhaus-side glitches resulting in temporary listings, sudden spikes in spam complaints, compromised accounts sending spam, and misconfigured email authentication settings. Proactive monitoring of sender reputation is also crucial for identifying and addressing deliverability issues before they escalate into blacklistings.

Key opinions

  • Spamhaus Glitches: Temporary listing glitches can occur on the Spamhaus side, causing IPs to be listed and then quickly removed.
  • Spam Complaints: A sudden increase in spam complaints can trigger blacklisting.
  • Compromised Accounts: Compromised email accounts can be used to send spam, leading to IP listings.
  • Authentication Issues: Misconfiguration of email authentication settings can negatively impact sender reputation.
  • Sender Reputation: It is important to proactively monitor your sender reputation.

Key considerations

  • Investigate Listing Cause: Determine the reason behind the listing, whether it's a Spamhaus glitch, spam complaints, compromised accounts, or authentication issues.
  • Implement Authentication: Ensure correct configuration of email authentication settings to improve deliverability.
  • Monitor Reputation: Proactively monitor sender reputation and deliverability metrics to identify potential problems.
  • Remediate Security: Consider improving security to stop compromised accounts.
Expert view

Expert from Email Geeks confirms that there may have been a listing glitch on Spamhaus today where a bunch of IPs were listed briefly and then removed.

April 2024 - Email Geeks
Expert view

Expert from SpamResource explains that a sudden blacklisting can be caused by a sudden increase in spam complaints, a compromised account sending spam, or a misconfiguration of email authentication settings.

May 2021 - SpamResource
Expert view

Expert from Word to the Wise shares that proactive monitoring of your sender reputation and deliverability metrics can help identify and address potential issues before they lead to blacklisting.

December 2021 - Word to the Wise

What the documentation says
6Technical articles

Spamhaus IP listings are primarily due to involvement in sending or supporting spam, which can include direct spam sending, hosting spammed websites, or providing services to spammers. The CSS list specifically identifies IPs with poor reputations based on spam activity, botnet infections, or malware distribution, often stemming from compromised systems. Resolution involves identifying and fixing the root cause, requesting delisting, and implementing preventative measures. Additionally, non-RFC compliant email practices like incorrect dates and headers, as well as improper SPF/DKIM records, can contribute to listings due to concerns about server control and potential spam origins.

Key findings

  • Involvement in Spam: IPs are listed for direct or indirect involvement in spam activities.
  • Compromised Systems: Compromised systems and networks contribute to poor IP reputation and CSS listings.
  • Non-Compliance: Non-RFC compliant email practices can signal spam and lead to listings.
  • Improper Authentication: Incorrect SPF/DKIM records indicate a lack of server control and increase the likelihood of being listed.
  • CSS Listings: Poor IP reputation resulting from botnet infections and malware distribution lead to IPs being listed on the CSS.

Key considerations

  • Identify and Resolve: Determine the cause of the listing by searching for spam activity and compromised systems.
  • Request Delisting: Request delisting through the Spamhaus website after resolving the issue.
  • Prevent Future Occurrences: Implement measures to prevent future spam activity and maintain a clean IP reputation.
  • Ensure RFC Compliance: Verify that email practices comply with RFC standards, including correct dates and headers.
  • Implement SPF/DKIM: Correctly set up SPF/DKIM records to assert server control and prevent spoofing.
Technical article

Documentation from Spamhaus explains that IPs and domains are listed due to involvement in sending or supporting spam. This includes direct spam sending, hosting spammed websites, or providing services to spammers.

March 2021 - Spamhaus
Technical article

Documentation from Spamhaus shares that the CSS (Composite Spam Score) lists IPs that have a poor reputation based on spam activity, botnet infections, or malware distribution. It is often due to compromised systems within the network.

April 2022 - Spamhaus
Technical article

Documentation from Spamhaus notes that resolution typically involves identifying and fixing the cause of the spam activity, requesting delisting through their website, and ensuring measures are in place to prevent future occurrences.

July 2024 - Spamhaus
Technical article

Documentation from URI DNSBL lists potential problems from sending email that is not RFC compliant. An example is incorrect dates and headers - this often signals to spam filters that the content may be spam and causes listing.

August 2024 - URI DNSBL
Technical article

Documentation from RFC-Editor explains that Spamhaus and other blocklists are often used to block e-mail that originates from compromised hosts or open relays. These are hosts that intentionally or unintentionally allow abusive traffic which includes spam.

January 2025 - RFC-Editor
Technical article

Documentation from DigitalOcean details the importance of an SPF record being correct on your DNS to ensure that email servers know that you have approved mail from your server. A lack of proper SPF and DKIM records often indicates a lack of server control which is an indicator of possible spam.

June 2024 - DigitalOcean