Summary
The most important email blacklists to monitor for deliverability issues are generally agreed to be Spamhaus and Barracuda, although the specific lists that are most relevant can depend on your recipients. Building and maintaining a positive sender reputation with major mailbox providers like Gmail and Outlook is critical, even more so than aggressively monitoring every blacklist. Smaller or less known blacklists can also have an impact, especially on more niche recipients. Monitoring engagement metrics and feedback loops is important. Keeping your email lists clean with Validity, ZeroBounce, or other similar systems is essential to reduce your risks of being added to a blacklist in the first place.
Key findings
- Spamhaus & Barracuda: Spamhaus and Barracuda are consistently identified as the most important blacklists to monitor.
- Sender Reputation is Key: Overall sender reputation with mailbox providers is even more crucial than monitoring blacklists alone.
- Relevance to Recipients: The importance of a specific blacklist depends on who you are sending emails to.
- Engagement Matters: Monitoring engagement metrics and feedback loops provides actionable insights.
- List Hygiene: Maintaining a clean email list is vital to avoid being blacklisted.
Key considerations
- Tailor Monitoring: Tailor your blacklist monitoring to the specific mailbox providers used by your recipients.
- Improve Reputation: Focus on building and maintaining a positive sender reputation through best practices and quality content.
- Monitor Feedback: Actively monitor engagement metrics, bounce rates, and feedback loops to identify and address deliverability issues proactively.
- Clean Your Lists: Regularly clean your email lists to remove invalid or inactive addresses.
- Rejection Messages: Examine any rejection messages.
What email marketers say
8 marketer opinions
Determining the most important email blacklists to monitor depends on various factors, primarily who you are sending emails to and the specific deliverability issues you are experiencing. While there is no one-size-fits-all answer, Spamhaus and Barracuda Reputation Block List are consistently recommended as key blacklists to monitor due to their widespread use. Maintaining a clean email list and focusing on overall sender reputation with major mailbox providers like Gmail and Outlook are also crucial. Smaller, less-known blacklists can be important if they affect deliverability to specific recipients. Internal metrics from mailbox providers are also key.
Key opinions
- Spamhaus: Spamhaus is consistently identified as a key blacklist to monitor due to its widespread use and significant impact on deliverability.
- Barracuda: Barracuda Reputation Block List is also frequently mentioned as an important blacklist, particularly for reaching corporate email addresses.
- Sender Reputation: Maintaining a positive sender reputation with major mailbox providers like Gmail and Outlook is critical, as their internal metrics heavily influence deliverability.
- List Hygiene: Maintaining a clean email list by removing invalid or inactive addresses is essential for avoiding blacklists.
- Relevance: The importance of a blacklist can be dependent on where your recipients are located.
Key considerations
- Recipient Base: Consider the specific recipients you are sending emails to, as the importance of a blacklist can vary depending on the mailbox providers they use.
- Internal Metrics: Pay attention to internal metrics and feedback loops from major mailbox providers, as they provide valuable insights into deliverability issues.
- Proactive Approach: Focus on proactive measures like maintaining a clean email list and monitoring sender reputation to prevent being blacklisted in the first place.
- Smaller Blacklists: Even smaller blacklists can be important. If having deliverability problems to a particular domain, these can be useful.
Marketer view
Email marketer from Mailjet shares that Spamhaus is a key blacklist to monitor. They also recommend checking against Proofpoint and Barracuda Reputation Block List, as these are commonly used by corporate filters and can significantly impact deliverability to business addresses.
9 Jan 2022 - Mailjet
Marketer view
Email marketer from Reddit recommends checking Spamhaus, Barracuda, and URIBL. They also noted that small, less-known blacklists can sometimes cause issues with specific recipients, so it's beneficial to monitor those as well if you have deliverability problems to a particular domain.
22 Jul 2021 - Reddit
What the experts say
3 expert opinions
The experts suggest a shift in focus from exhaustively monitoring all blacklists to prioritizing a few key ones and understanding overall IP reputation. Spamhaus and Barracuda are highlighted as relevant due to their widespread use. More importantly, focusing on maintaining a good IP reputation and monitoring engagement metrics and feedback loops with mailbox providers is crucial.
Key opinions
- Spamhaus & Barracuda: Spamhaus and Barracuda are considered relevant blacklists due to their wide usage.
- IP Reputation > Blacklists: Overall IP reputation and how mailbox providers view sending practices are more critical than simply monitoring blacklists.
- Engagement & Feedback: Monitoring engagement metrics and feedback loops provides more actionable insights into deliverability than blacklist monitoring alone.
Key considerations
- Focus on Key Lists: Prioritize monitoring a few key blacklists rather than trying to track every single one.
- Understand Reputation: Invest time in understanding and improving your IP reputation.
- Monitor Engagement: Actively monitor engagement metrics and feedback loops to identify and address deliverability issues.
- Rejection Messages: If you have rejection messages, they tell you what you need to know. If you don't, then there's probably no real deliverability problem.
Expert view
Expert from Email Geeks explains that most blacklists are worthless because it's trivial to run one. Running a useful reputation service with accurate data used by many inboxes is much harder. Relevant ones are Spamhaus, Barracuda, and maybe Spamcop. Being listed on others might signal potential problems but won't cause immediate delivery issues. If you have rejection messages, they tell you what you need to know; otherwise, there isn't really a problem.
16 Sep 2023 - Email Geeks
Expert view
Expert from Word to the Wise (Laura Atkins) explains that rather than focusing solely on specific blacklists, it's crucial to understand your overall IP reputation and how mailbox providers view your sending practices. Monitoring engagement metrics and feedback loops is important.
28 Jul 2023 - Word to the Wise
What the documentation says
4 technical articles
The documentation suggests focusing on actively monitoring your sending reputation by understanding how different email providers are filtering messages. The Spamhaus SBL and ZEN lists are widely used, Microsoft relies on internal and external systems, Barracuda uses BRBL to filter based on poor reputation, and Proofpoint has its own internal system. Sender reputation is a key factor.
Key findings
- Spamhaus SBL/ZEN: Spamhaus SBL and ZEN are widely used blocklists.
- Microsoft's Internal Lists: Microsoft uses internal lists and external systems, making sender reputation critical for Outlook.com deliverability.
- Barracuda BRBL: Barracuda's BRBL impacts deliverability to organizations using their email security solutions.
- Proofpoint's Internal System: Proofpoint maintains an internal system based on spam traps, complaints, and patterns, affecting deliverability to their users.
Key considerations
- Monitor Reputation: Actively monitor your sender reputation across major providers.
- Follow Best Practices: Adhere to email sending best practices to avoid being flagged by filters.
- Understand Filtering Systems: Familiarize yourself with how different email providers filter messages.
Technical article
Documentation from Barracuda explains that the Barracuda Reputation Block List (BRBL) is a real-time database of IP addresses with a poor reputation due to spamming activities. Inclusion on this list can significantly impact email delivery to organizations using Barracuda's email security solutions.
17 Oct 2023 - Barracuda
Technical article
Documentation from Spamhaus.org explains that Spamhaus maintains several blocklists, including the SBL (Spamhaus Block List), which lists IP addresses involved in direct spam activities, and the ZEN list, a combination of SBL, XBL (Exploit Block List), and PBL (Policy Block List) offering comprehensive coverage. These lists are widely used by email servers to filter out spam.
2 May 2025 - Spamhaus.org
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