What caused the Spamhaus IP blacklisting issue and how was it resolved?

Summary

Spamhaus IP blacklisting can occur due to a multitude of reasons ranging from Spamhaus internal technical 'blips' to issues like spam, malware, spam traps, high bounce rates, being part of a botnet, subscriber complaints, sending to invalid addresses, poor sending practices, sudden spikes in volume, spam-like content, low engagement, and poor infrastructure. Resolution commonly involves cleaning lists, improving practices, IP warming, authentication, monitoring reputation, contacting blacklist providers, securing systems, and adhering to best practices. Monitoring blacklists and identifying cause and adhering to specific delisting policies are key.

Key findings

  • Multifaceted Causes: Blacklisting can arise from both technical issues at Spamhaus and a wide array of poor sending practices.
  • Comprehensive Resolution: Addressing the issue requires a multi-pronged approach including fixing technical issues, improving email practices, and engaging with blacklist providers.
  • Proactive Monitoring Crucial: Regular monitoring of blacklists, sender reputation, and adherence to best practices are essential.

Key considerations

  • Address all factors: Acknowledge that many factors can cause blacklisting, from email content to security.
  • List Hygiene Matters: Invest heavily in regular email list cleaning and engagement monitoring.
  • Ensure Proper Authentication: Prioritize email authentication (SPF, DKIM, DMARC) and adhere to sender guidelines.
  • Understand Specific Policies: Always review the specific delisting policies for the specific blacklist.

What email marketers say
11Marketer opinions

Spamhaus IP blacklisting can occur due to various reasons, including technical glitches at Spamhaus, spam traps, high bounce rates, being part of a botnet, subscriber complaints, sending to old or invalid email addresses, poor sending practices, sudden spikes in email volume, spam-like content, low engagement, and poor sending infrastructure. Resolutions involve technical fixes by Spamhaus, cleaning email lists, improving sending practices, warming up new IPs, authenticating email, monitoring sender reputation, contacting the blacklist provider, improving email validation practices, implementing double opt-in, ensuring recipient opt-in, setting up feedback loops, thoroughly investigating the cause, implementing corrective measures, and actively engaging with blacklist providers for delisting. Communications about incidents may be found on platforms like Twitter and LinkedIn.

Key opinions

  • Multiple Causes: Blacklisting stems from diverse issues: technical errors to poor email practices.
  • Proactive Monitoring: It's essential to monitor sender reputation and blacklist status regularly.
  • Communication Channels: Information about blacklisting events can be found on various platforms.
  • Delisting Process: Resolving blacklisting involves fixing the cause and requesting delisting.

Key considerations

  • List Hygiene: Maintaining a clean and engaged email list is crucial.
  • Authentication: Proper email authentication (SPF, DKIM, DMARC) is vital.
  • Sending Practices: Adhering to best practices for email sending volume and content is necessary.
  • Incident Response: Have a plan to quickly identify, address, and communicate about blacklisting incidents.
Marketer view

Marketer from Email Geeks mentions communications about the Spamhaus incident are available on Twitter and LinkedIn.

June 2023 - Email Geeks
Marketer view

Email marketer from Mailjet explains that being blacklisted may be caused by multiple issues, which can be anything from subscriber complaints to sending to old email addresses or using poor sending practices. They can be resolved by improving list hygiene, warming up new IP addresses, authenticating email, and monitoring sending reputation. You should be able to delist yourself when the issue is resolved.

June 2023 - Mailjet
Marketer view

Marketer from Email Geeks shares that something went wrong with Spamhaus, and they stopped it and are purging the listings. Tickets will be deleted en masse.

April 2022 - Email Geeks
Marketer view

Email marketer from Email Marketing Forum shares that resolving blacklisting involves thoroughly investigating the cause, implementing corrective measures like improving list quality, and actively engaging with blacklist providers for delisting.

May 2024 - Email Marketing Forum
Marketer view

Email marketer from StackOverflow shares that common causes for email blacklisting include spam traps, low engagement, and poor sending infrastructure. Solving this issue would be to improve email validation practices, implement double opt-in, and monitor sender reputation.

August 2023 - StackOverflow
Marketer view

Email marketer from SparkPost Blog explains that sending too many emails too quickly from a new IP can trigger blacklisting. The resolution involves gradually increasing sending volume (IP warming), monitoring reputation, and ensuring proper email authentication.

January 2022 - SparkPost Blog
Marketer view

Email marketer from Reddit explains that IP blacklisting can occur due to sudden spikes in email volume or spam-like content. Resolution may involve contacting the blacklist provider, improving sender reputation, and ensuring compliance with email marketing best practices.

December 2021 - Reddit
Marketer view

Email marketer from Woodpecker explains that a sudden spike in bounce rates, low engagement rates, and poor list hygiene can get you blacklisted. You should fix the issues and then request to be removed.

September 2021 - Woodpecker.co
Marketer view

Email marketer from Snov.io explains how to check if your IP address or domain is on an email blacklist. If you are you need to identify the reason for the blacklisting, take action to address the issue and then contact the blacklist provider to request delisting.

August 2022 - Snov.io
Marketer view

Email marketer from Email Hippo Blog shares that Spamhaus listings can be caused by spam traps, high bounce rates, or being included in a botnet. Resolution involves cleaning email lists, improving sending practices, and requesting delisting from Spamhaus.

January 2025 - Email Hippo Blog
Marketer view

Email marketer from SendPulse shares that reasons for blacklisting includes spam complaints, sending to invalid addresses, or poor IP reputation. Solution consists of ensuring recipient opt-in, cleaning email lists, setting up feedback loops, authenticating emails, and initiating the delisting process.

September 2021 - SendPulse

What the experts say
3Expert opinions

A Spamhaus IP blacklisting issue can stem from technical glitches resolved by Spamhaus or from typical DNSBL reasons like sending spam or malware. Resolutions involve either Spamhaus's own fixes, or identifying, correcting, and requesting delisting. Monitoring blacklists proactively is essential to address issues and reviewing/contacting blocklist policies.

Key opinions

  • Cause Variety: Blacklisting can arise from both internal system errors within Spamhaus and external actions related to spam and malware.
  • Resolution Steps: Resolving a blacklisting issue involves identifying the cause, fixing it, and requesting delisting.
  • Proactive Monitoring: Regular monitoring of blacklists is essential for early detection and quick resolution of IP issues.

Key considerations

  • Technical Issues: Recognize that blacklisting can sometimes be due to technical issues outside of your control.
  • Investigate Listings: Take immediate steps to find out exactly why you are on a blocklist and fix any issues.
  • Policy Review: Always review the specific delisting policies for the specific blacklist you are listed on.
Expert view

Expert from Email Geeks explains there was a blip on Spamhaus listings. Spamhaus is aware and they are on it, and it's been resolved. If a ticket was opened, a response may not be received due to the high volumes of tickets Spamhaus received.

April 2021 - Email Geeks
Expert view

Expert from Spamresource.com explains that IP addresses get listed on DNSBLs (DNS Blacklists) for various reasons including sending spam, malware, or exhibiting suspicious activity. Resolution typically involves identifying the cause of the listing, correcting the issue, and then requesting delisting from the specific DNSBL.

June 2023 - Spamresource.com
Expert view

Expert from Word to the Wise shares you need to monitor blacklists to proactively address IP issues. If you get on a blocklist you need to find out why and resolve the issue, you should always review the blocklist's policies and attempt to contact them to resolve the issue.

December 2024 - Word to the Wise

What the documentation says
5Technical articles

Spamhaus IP blacklisting, as indicated by documentation, arises from spam or malware activities, sending unsolicited emails, compromised servers, and poor sender reputation due to factors like spam rate and authentication issues. Resolution universally involves identifying the cause of the listing, rectifying the issue (securing systems, improving authentication, maintaining low spam rates), and then requesting delisting. Microsoft also recommends sending only wanted emails, setting up SPF records, and joining Microsoft SNDS.

Key findings

  • Root Causes: Blacklisting is a consequence of sending spam, malware, unsolicited emails, or having compromised servers, all contributing to poor sender reputation.
  • Resolution Process: The standard resolution includes identifying the cause, fixing the problem, and requesting delisting.
  • Proactive Measures: Maintaining low spam rates, implementing proper email authentication (SPF, DKIM, DMARC), and adhering to sender guidelines are key to avoiding blacklisting.

Key considerations

  • Security: Ensure your systems are secure and not compromised to send unsolicited emails.
  • Authentication: Implement and maintain proper email authentication protocols (SPF, DKIM, DMARC).
  • Sender Reputation: Actively monitor and manage your sender reputation to maintain good standing with email providers.
Technical article

Documentation from Google Postmaster Tools shows that factors impacting sender reputation, which can lead to blacklisting, include spam rate, IP reputation, and authentication. To avoid blacklisting, best practices such as maintaining low spam rates, authenticating emails, and adhering to Google's sender guidelines should be followed.

April 2024 - Google
Technical article

Documentation from DigitalOcean shares that blacklisting can result from sending unsolicited emails or having compromised servers. Resolving the issue often involves identifying and securing compromised systems, improving email authentication, and requesting delisting after addressing the cause.

October 2024 - DigitalOcean
Technical article

Documentation from MXToolbox describes that blacklists aggregate information about IPs and domains known for sending spam. To resolve issues, identify which lists you're on, determine the reason, fix it, and request delisting.

April 2024 - MXToolbox
Technical article

Documentation from Spamhaus.org explains that the Spamhaus Block List (SBL) lists IP addresses involved in spam or malware activities. It is resolved by identifying and rectifying the cause of the listing, then requesting delisting.

September 2022 - Spamhaus.org
Technical article

Documentation from Microsoft shares the SmartScreen Filter in Outlook identifies spam messages, and can lead to blocking your server. Improve reputation by only sending wanted emails, setting up SPF records, and joining Microsoft SNDS.

October 2022 - Microsoft