Why is my domain listed in Razor2 and how do I remove it?
Matthew Whittaker
Co-founder & CTO, Suped
Published 10 Jul 2025
Updated 15 Aug 2025
7 min read
Discovering that your domain is listed in Razor2 can be a confusing experience, especially if you believe your email sending practices are clean. Unlike many other common blocklists (or blacklists), Razor2 doesn't operate as a traditional Real-time Blackhole List (RBL) that targets IP addresses or domains directly based on general reputation or known spam sources. This distinction is crucial because it means the usual delisting procedures you might be familiar with simply won't apply.
Instead, Razor2 focuses on the actual content of your emails, using a sophisticated system that analyzes message bodies. This means that even if your domain isn't sending bulk emails, a listing can still occur if any messages originating from your domain contain content (or variations of it) that the Razor2 network has identified as spam. Understanding this fundamental difference is the first step toward diagnosing and resolving the issue.
Understanding Razor2 and how it works
Razor2 is a distributed, collaborative spam detection system that primarily works with SpamAssassin, a widely used open-source spam filter. It operates by generating fuzzy checksums of email messages. When a user reports a spam email, Razor2 generates a unique cryptographic hash (checksum) of the message's content. If enough users report the same or very similar content, that checksum is added to the Razor2 database. Subsequently, any new emails with matching checksums are flagged as potential spam.
This content-centric approach is what sets Razor2 apart. It isn't evaluating your sending IP's reputation or your domain's sending history in the same way a DNS-based blacklist (DNSBL) would. Instead, it's focused on patterns in the email body, subject line, or even URLs embedded within the message. The system's strength lies in its collective intelligence: the more users report identical spam, the stronger the signal becomes for that content.
Razor2 characteristics
Content-based: Focuses on fuzzy checksums of email content, not IP or domain.
Collaborative network: Users submit spam, which helps identify patterns globally.
No direct delisting: Unlike traditional blocklists, there's no form to fill out to be removed from Razor2.
Why your domain might be flagged by Razor2
Even though Razor2 isn't a domain blocklist in the traditional sense, your domain might still be implicated if it's sending emails containing content that matches Razor2's spam database. This often happens due to a few common scenarios, even if you're not intentionally sending bulk email.
One primary reason is a compromised system. If an email server, website, or application associated with your domain is compromised, spammers can use it to send out large volumes of unsolicited emails. These emails will likely contain spammy content that gets reported to Razor2, linking your domain (or its associated IPs) to the offending content. This means you might be listed without your direct knowledge or intention.
Another common cause is unintended spammy content. Perhaps an old email template contains phrases, links, or a structure that has previously been used in spam campaigns and added to the Razor2 database. Even legitimate marketing campaigns can inadvertently trigger Razor2 if their content shares characteristics with known spam, leading to deliverability issues where your emails go to spam. Regularly checking your DMARC monitoring reports can reveal unexpected sending sources or large volumes of emails that you weren't aware of, providing critical clues as to why your domain is being flagged by Razor2.
Practical steps to address a Razor2 listing
Given that Razor2 is a content-based system and not a traditional IP or domain blacklist (blocklist), there's no direct delisting request or removal form to fill out. This is a common point of confusion for many senders, as the process differs significantly from getting delisted from other blocklists.
The primary solution for a Razor2 listing involves identifying and stopping the source of the problematic email content. This means you need to: Investigate Sending Sources: Utilize your DMARC reports (RUA and RUF) to gain visibility into all systems sending email on behalf of your domain. This can help you uncover compromised servers or applications you weren't aware of. Look for unexpected IPs or email service providers in your DMARC reports. Once identified, secure or shut down any unauthorized sending.
Furthermore, you need to Review Email Content: Analyze the content of the emails that are being flagged. This could involve removing specific spammy phrases, suspicious links, or certain HTML structures. If you are using SpamAssassin directly, its logs might provide clues about what specific Razor2 rules are being triggered. It's about changing the patterns that Razor2 detects as spam, rather than requesting a removal. Over time, as your sending content becomes clean, the Razor2 network will stop flagging your emails.
Monitoring and prevention for long-term health
Proactive measures are always better than reactive ones when it comes to email deliverability. Implementing a robust blocklist monitoring strategy and leveraging email authentication protocols are essential for maintaining a healthy sending reputation and avoiding future issues with content-based filters like Razor2.
Consistently monitoring your domain reputation and tracking your email performance can provide early warnings of potential problems. Tools that offer detailed analytics on bounce rates, spam complaints, and overall inbox placement will help you pinpoint issues before they escalate into major problems, ensuring your messages reach their intended recipients. Also ensure that you know what happens when your domain is put on a blocklist.
Implementing and enforcing email authentication, such as DMARC, is also crucial. DMARC provides comprehensive visibility into your email ecosystem, allowing you to see who is sending emails on your behalf and whether those emails pass authentication checks. This insight is invaluable for quickly identifying and shutting down unauthorized sending, which is often a root cause of content-based blocklistings like Razor2. Staying vigilant about your content and sending practices is key to avoiding future issues.
Navigating Razor2 listings
Addressing a Razor2 listing requires a shift in perspective compared to dealing with traditional IP or domain blacklists. Instead of seeking a direct delisting, the focus must be on understanding and rectifying the underlying content issues that led to the flag. This involves a thorough investigation of all sending sources associated with your domain and a meticulous review of your email content for any spammy characteristics.
Proactive email hygiene, continuous monitoring, and robust email authentication are not just best practices, but necessities. By focusing on these areas, you can significantly improve your overall email deliverability, ensure your legitimate messages reach the inbox, and prevent future encounters with content-based spam filters like Razor2.
Views from the trenches
Best practices
Actively use DMARC monitoring to gain full visibility over all sending sources using your domain, including any unauthorized senders.
Common pitfalls
Expecting a direct delisting process, as Razor2 functions differently from traditional IP/domain blacklists.
Expert tips
Regularly audit your email content, including subject lines, body text, and embedded URLs, for anything that could be misinterpreted as spam by content filters.
Expert view
Expert from Email Geeks says that Razor2 is not an RBL, but rather a distributed fuzzy checksum based filter that operates on the message body.
2020-03-17 - Email Geeks
Expert view
Expert from Email Geeks says that if a message triggers Razor2 hits, it indicates the email body looks like spam previously flagged by the Razor2 network.
SpamAssassin directly, its logs might provide clues about what specific Razor2 rules are being triggered. It's about changing the patterns that Razor2 detects as spam, rather than requesting a removal. Over time, as your sending content becomes clean, the Razor2 network will stop flagging your emails.
