How relevant is the SpamRats blacklist for email deliverability and what should I do if my IP or domain is listed?

Key findings

• Limited relevance: SpamRats is generally not considered a highly relevant blocklist by email deliverability professionals for legitimate email senders.
• IP-based listing: The blacklist primarily focuses on IP addresses, especially those typically assigned to residential or dynamic internet connections. These are often indicators of compromised machines or botnets sending spam.
• Malware indicator: If an IP address resembling a consumer ISP pool (or NAT) is sending SMTP traffic and appears on SpamRats, it strongly suggests the presence of malware or a Trojan. This information is available from the SpamRats website.
• Domain vs. IP: While SpamRats lists IPs, a domain might appear listed if its associated A record IP is on the blacklist, potentially due to operator error in interpreting the listing.

Key considerations

• Check other blocklists: A listing on SpamRats might not be a major concern on its own, but it's always wise to check if your IP or domain is listed on more widely used and impactful blacklists (e.g., Spamhaus, SORBS). You can use a blocklist checker to do this.
• Reverse DNS: Ensure your sending IP address has proper reverse DNS (rDNS) configured. Poor rDNS can contribute to an IP being flagged as suspicious, even by less relevant lists.
• Sender reputation: Focus on improving your overall sender reputation by maintaining clean lists, avoiding spam traps, and authenticating your emails properly.
• Investigate root cause: If a legitimate organizational IP is listed, investigate if there's any unauthorized SMTP traffic originating from it, which could indicate a compromise or misconfiguration.

Key opinions

• Unexpected discovery: Marketers are often surprised when they find their domain or IP listed on less common blacklists like SpamRats, as they may never have heard of them before.
• Initial concern: The immediate reaction is often to question the legitimacy or impact of such a listing, especially when previous checks didn't show any issues.
• Trust in primary lists: There's a general understanding that some blacklists are far more critical than others for email deliverability, and not all listings have equal consequences.
• Focus on the basics: Marketers are reminded to ensure their core email sending practices are sound, regardless of minor blacklist appearances.

Key considerations

• Impact assessment: Before taking drastic action, marketers should assess the actual impact of a SpamRats listing on their email delivery. It's important to understand what happens when your IP gets blocklisted by various RBLs.
• Distinguish IP vs. domain: Understand if the listing is truly for your domain or if it's an IP associated with your domain (e.g., web hosting) that's causing the flag.
• Hosting services: If a web hosting service's IP is listed on SpamRats, even if not used for email, it might warrant considering alternative providers for mail routing if their network reputation is generally poor. Some IPs are flagged due to poor sender reputation.
• Prioritize major blacklists: Always prioritize monitoring and resolving listings on major, influential blacklists like Spamhaus or CBL, as they have a much broader impact on deliverability.

Key opinions

• Low relevance: Many experts state that SpamRats is not particularly relevant for organizational email deliverability.
• Dynamic IP focus: The blacklist primarily targets dynamic IP addresses commonly found in consumer ISP pools, which are often indicative of botnets or infected machines.
• Operator error: If a legitimate sender's IP or domain appears listed, it could sometimes be due to an 'operator error' in how the listing is being interpreted or used by the querying system (GIGO - Garbage In, Garbage Out).
• Reverse DNS importance: Properly configured reverse DNS for your sending IP is crucial, as its absence or misconfiguration can lead to suspicious flags from various systems.

Key considerations

• Ignore if appropriate: If you are confident your IP is statically assigned and has good reverse DNS, and your email sending practices are sound, you might be able to ignore a SpamRats listing without significant impact.
• Source of listing: Differentiate between an IP-based listing (RATS-Dyna) and an accidental hostname lookup. Understanding DNSBLs is key.
• Focus on reputation: Prioritize maintaining a strong sender reputation overall. This involves clean lists, proper authentication (SPF, DKIM, DMARC), and avoiding spam complaints. The importance of IP reputation is universal across all blacklists.
• Monitor broader impact: While SpamRats itself may have limited reach, it's wise to ensure the issue isn't symptomatic of a broader problem that could lead to listings on more impactful blacklists.

Key findings

• Purpose: SpamRats aims to stop spam originating from IP addresses that are not intended to be mail servers, such as home connections or compromised hosts.
• Target audience: The blacklist primarily targets dynamic IP ranges (RATS-Dyna) and IPs that exhibit suspicious behavior typically associated with malware or botnets.
• Mechanism: It operates as an IP-based blocklist service, used by mail servers to check incoming connections against its database.
• Heuristics: SpamRats uses heuristics to identify IPs that 'smell like' consumer ISP pools or NAT, inferring that SMTP traffic from such IPs is reliably indicative of malware.

Key considerations

• Specific IP types: If your IP is listed, consider if it's a dynamic IP or an IP that might be misinterpreted by SpamRats' heuristics as a consumer connection. This is why proper identification of IP issues is critical.
• Reverse DNS: Ensure your sending IP has a valid and appropriate reverse DNS entry. Misconfigured rDNS can lead to a less favorable assessment by such RBLs.
• Traffic analysis: If a legitimate IP is listed, review your network for any unauthorized SMTP traffic, which could point to an internal compromise or misconfigured device sending mail.
• Limited adoption: While documented, the actual adoption rate by major mailbox providers of SpamRats as a primary blocking mechanism is generally considered low.