Summary
Reputable senders can be listed by Spamhaus for a multitude of reasons spanning technical misconfigurations, list hygiene issues, and malicious attacks. Key issues include legitimate spam trap hits, potential (even unintentional) engagement in spamming activities, list bombing attacks, inconsistent sending practices, compromised accounts, shared IP address blacklisting, poor email authentication, high bounce rates, improper DNS records, sudden volume spikes, unengaged subscribers, problematic content, and mismanaged unsubscribes. Spamhaus listings, particularly the 'June' listings, should be taken seriously as indicators of deliverability problems.
Key findings
- Spamhaus Legitimacy: Spamhaus listings are legitimate and reflect real issues needing attention.
- Spam Trap Hits: Hitting spam traps, even accidentally, leads to blacklisting.
- Inadvertent Spamming: Reputable senders may unknowingly engage in spam-like behavior.
- List Bombing Attacks: List bombing can artificially inflate complaints and spam trap hits.
- Inconsistent Sending: Unstable sending volumes and infrastructure changes raise red flags.
- Compromised Systems: Compromised accounts and servers can be exploited for spam campaigns.
- Poor Authentication: Lack of SPF, DKIM, and DMARC negatively impacts sender reputation.
- List Hygiene: Poor list hygiene leads to high bounce rates and spam trap hits.
- Technical Misconfigurations: Improper DNS and reverse DNS records harm sender trustworthiness.
- Subscriber Engagement: Low subscriber engagement contributes to higher complaint rates.
- Content Issues: Problematic email content can trigger spam filters.
- Unsubscribe Handling: Mismanaged unsubscribes lead to increased complaints.
Key considerations
- Monitor Reputation: Continuously monitor sender reputation and blacklist status.
- Investigate Listings: Promptly investigate the root cause of any Spamhaus listing.
- Improve List Hygiene: Implement rigorous list cleaning and validation practices.
- Strengthen Security: Enhance security measures to prevent account compromises.
- Authenticate Emails: Properly configure SPF, DKIM, and DMARC records.
- Manage Sending Volume: Maintain consistent and predictable sending volumes.
- Review Content: Carefully review email content for potential spam triggers.
- Handle Unsubscribes: Efficiently process unsubscribe requests to prevent further complaints.
- Implement Feedback Loops: Set up feedback loops to monitor complaint rates.
- Protect Against Attacks: Implement safeguards against list bombing and other malicious attacks.
What email marketers say
8 marketer opinions
Even reputable senders can face Spamhaus listings due to various factors. These include sudden spikes in email volume, sending to unengaged or invalid email addresses, increased spam complaints, inconsistent sending volume, a sudden influx of unconfirmed subscribers, neglecting list cleaning, problematic email content triggering spam filters, and improper management of unsubscribe requests. These issues, even when unintentional, can lead to blacklisting.
Key opinions
- Volume Spikes: Sudden increases in email volume can trigger Spamhaus filters.
- List Hygiene: Sending to old, unengaged, or invalid email addresses increases the risk of spam trap hits.
- Complaint Rates: High spam complaint rates, even from a small portion of recipients, can lead to listings.
- Sending Consistency: Inconsistent sending volume and sudden changes in sending IPs can raise suspicion.
- Subscriber Opt-in: A sudden influx of new subscribers who haven't confirmed their subscription can increase complaints.
- Content Triggers: Certain keywords or phrases in email content can trigger spam filters.
- Unsubscribe Management: Failing to properly manage unsubscribe requests can lead to recipients marking emails as spam.
Key considerations
- Monitor Sending Volume: Avoid sudden spikes in email volume and maintain consistent sending patterns.
- Practice List Hygiene: Regularly clean email lists to remove inactive, invalid, and unengaged addresses.
- Monitor Complaint Rates: Actively monitor and address spam complaint rates, taking steps to understand and mitigate the causes.
- Implement Double Opt-in: Use double opt-in for new subscribers to ensure they genuinely want to receive emails.
- Review Email Content: Carefully review email content to avoid using keywords or phrases that might trigger spam filters.
- Manage Unsubscribes: Ensure unsubscribe requests are promptly and properly processed to prevent further emails to unsubscribed recipients.
Marketer view
Email marketer from EmailDrips shares a cause may be a sudden influx of new subscribers who haven't fully opted in or confirmed their subscription, leading to increased spam complaints.
4 Jan 2025 - EmailDrips
Marketer view
Email marketer from Reddit suggests that even with good segmentation, senders can hit old or invalid email addresses, leading to spam trap hits. Spamhaus uses these hits as a factor in their listings.
15 May 2025 - Reddit
What the experts say
6 expert opinions
Reputable senders can be listed by Spamhaus for several reasons. These include legitimately hitting spam traps, potentially engaging in actual spamming despite their reputation, and being targeted in a list bombing attack. Additionally, changes in sending IP addresses, domains, or inconsistent sending volumes can make a sender appear suspicious. Listings from Spamhaus are legitimate; if a sender got June listings, it's highly likely that spam traps are being hit.
Key opinions
- Legitimate Listings: Spamhaus listings are legitimate indicators of deliverability issues.
- Spam Trap Hits: Hitting spam traps, even unintentionally, leads to listings.
- Potential Spamming: Reputable senders may inadvertently be engaging in spam-like activities.
- List Bombing: Senders can be targeted by list bombing attacks, leading to spam complaints and trap hits.
- Inconsistent Sending: Changing IPs, domains, or having inconsistent sending volumes can raise suspicion.
Key considerations
- Investigate Spam Traps: Investigate and address the causes of hitting spam traps.
- Review Sending Practices: Thoroughly review sending practices to identify any spam-like activities, even unintentional ones.
- Monitor Sending Reputation: Monitor your sending reputation and take steps to mitigate any negative impacts.
- Protect Against List Bombing: Implement measures to protect against list bombing attacks.
- Maintain Consistent Sending: Maintain consistent sending volumes and avoid sudden changes to IPs and domains.
Expert view
Expert from Email Geeks shares that them being caught as snowshoers makes even less sense than they have a bad segment or a few traps.
19 Dec 2023 - Email Geeks
Expert view
Expert from SpamResource explains that a reputable sender might get listed if they are the target of a list bombing attack, where spammers sign up numerous email addresses (including spam traps) to the sender's mailing list, resulting in a sudden spike in spam complaints and trap hits.
28 Jul 2024 - SpamResource
What the documentation says
6 technical articles
Reputable senders might face Spamhaus listings for technical reasons, including inadvertently mimicking spammer behavior, compromised accounts, being on a blacklisted IP range, poor email authentication (SPF, DKIM, DMARC), high bounce rates, and improper DNS records. These technical oversights can damage sender reputation and lead to blacklisting.
Key findings
- Spammer Mimicry: Sending practices inadvertently matching those of spammers can lead to listings.
- Compromised Accounts: Compromised accounts or servers can be used to send spam without the sender's knowledge.
- Shared IP Blacklisting: IP addresses can be blacklisted due to the behavior of other users on the same network range.
- Poor Authentication: Lack of SPF, DKIM, and DMARC records can make emails appear suspicious.
- High Bounce Rates: Failing to manage bounce rates indicates poor list hygiene and can lead to blacklisting.
- Improper DNS: Failing to maintain proper DNS records and reverse DNS lookups makes the sender appear less trustworthy.
Key considerations
- Review Sending Practices: Regularly audit sending practices to ensure they don't inadvertently mimic spammer behavior.
- Secure Accounts: Implement robust security measures to prevent account compromises.
- Monitor IP Reputation: Monitor IP reputation and be aware of the behavior of other users on shared IP ranges.
- Implement Authentication: Implement SPF, DKIM, and DMARC records to authenticate emails.
- Manage Bounces: Actively manage bounce rates and clean email lists to remove invalid addresses.
- Maintain DNS Records: Ensure proper DNS records and reverse DNS lookups are maintained for sending IPs.
Technical article
Documentation from cPanel explains that a possible cause is poor email authentication practices, such as not implementing SPF, DKIM, and DMARC records, which can make emails appear suspicious to Spamhaus.
5 Mar 2022 - cPanel
Technical article
Documentation from Microsoft explains failing to adhere to best practices for managing bounce rates can cause issues. High bounce rates indicate poor list hygiene and can lead to blacklisting.
2 Feb 2023 - Microsoft
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