How relevant is the SpamRats blacklist for email deliverability and what should I do if my IP or domain is listed?
Matthew Whittaker
Co-founder & CTO, Suped
Published 27 Jul 2025
Updated 16 Aug 2025
7 min read
Email blacklists (or blocklists) are crucial for filtering out unwanted email, but their individual relevance varies widely. When an IP address or domain is listed on a blacklist, it can significantly hinder email deliverability, leading to messages being blocked or routed to spam folders. Among the many blacklists in operation, SpamRats is one that email professionals often encounter. Understanding its specific purpose and impact is key to knowing how to react if your sending infrastructure gets listed.
SpamRats, as its name implies, aims to identify sources of spam and malicious traffic. Its most prominent list, RATS-Dyna, specifically targets IP addresses that behave suspiciously. This often includes dynamic IP addresses or those within consumer ISP ranges that should not typically be sending direct SMTP traffic. Such activity is frequently indicative of compromised systems, like PCs infected with Trojans or malware, attempting to send spam.
While SpamRats has been around for a long time, its relevance for most legitimate email marketers and businesses can be limited compared to other, more widely adopted blacklists, such as Spamhaus. Mailbox providers typically consult a variety of blocklists, and some carry more weight than others. If you are using a dedicated, static IP address with proper reverse DNS, a listing on SpamRats might have minimal impact on your deliverability, depending on the specific recipient's filtering policies. However, it's still something to address if it's causing delivery issues.
When an IP address or domain is blacklisted, its reputation is negatively affected, which can lead to emails being rejected, delayed, or sent directly to the junk folder. This is a common outcome for any email blocklist listing. Specifically, with SpamRats, if your IP is listed, mail servers that use this blacklist for filtering might reject emails originating from that IP. The rejection messages (bounce codes) would typically indicate the reason for the block, often mentioning SpamRats directly.
The primary impact you'd notice is a sudden increase in bounce rates for emails sent to certain recipients, or a drop in inbox placement. While SpamRats is primarily an IP-based blacklist, if your domain is associated with a blacklisted IP (e.g., through its A record or MX record), it can still affect your domain's sending reputation. This is why it’s important to understand the interconnectedness of IP and domain reputation.
A listing on SpamRats, particularly for a legitimate mail server, could indicate an underlying issue, such as a compromised system, an open relay, or misconfigured reverse DNS. The list aims to identify suspicious patterns that might suggest malware or botnet activity. Thus, a listing, even if considered minor by some, warrants investigation to ensure the integrity of your sending infrastructure.
Understanding the impact
An unexpected SpamRats listing can signal a compromise. While it might not be as impactful as major blacklists, ignoring it could leave vulnerabilities unaddressed, potentially leading to more severe reputation issues down the line. It’s a good practice to always investigate the underlying cause.
How to check for a SpamRats listing
The first step if you suspect an issue is to confirm whether your IP or domain is indeed listed on SpamRats. You can use various online tools to check for IP and domain blocklist presence. The SpamRats website also provides a direct lookup tool where you can enter your IP address to see its status on their various lists, such as RATS-Dyna or RATS-NoPtr.
For a more technical check, you can perform a DNS query for your IP address against the SpamRats DNSBL (DNS-based Blackhole List). This is done by reversing your IP octets, appending the specific SpamRats DNSBL zone, and performing an A record lookup. If a result is returned, your IP is listed. Here’s an example for a hypothetical IP:
DNS lookup example for SpamRatsBASH
dig +short 2.0.0.127.dnsbl.spamrats.com
The example IP 127.0.0.2 is often used in DNSBLs to indicate a listing, but a real listing would show your actual IP and a specific return code (e.g., 127.0.0.x). Confirming the listing is the initial step to verify if SpamRats is indeed causing delivery issues.
Steps to take if listed
If you find your IP or domain listed on SpamRats, the first action is not to panic. Evaluate the type of listing (e.g., RATS-Dyna, RATS-NoPtr). RATS-Dyna indicates a dynamic IP or an IP that shouldn't be sending direct mail, while RATS-NoPtr specifically lists IPs without valid reverse DNS. The key is to understand why you were listed.
For RATS-Dyna, if you are a legitimate sender using a static IP, the listing might be a false positive due to SpamRats' heuristics or a shared IP from a web hosting service (like OVH, as sometimes seen) that was previously abused. If you are using a consumer ISP connection to send bulk email directly, you should cease this practice and use a proper SMTP service. For RATS-NoPtr, ensure your IP address has correct reverse DNS configured.
SpamRats offers a delisting request tool on its website. Input your IP address, follow the instructions, and submit the request. While some users report that their delisting tool may not always be responsive, it's the official channel to use. If the issue persists, ensure you’ve addressed any underlying problems on your end before re-attempting delisting. In some cases, if you're confident your IP is clean and your reverse DNS is correct, and if the listing is not causing significant deliverability issues, some recommend to simply ignore it, especially if it’s a statically assigned IP.
Identifying the problem
Verify listing: Confirm your IP/domain is indeed on SpamRats via their website or DNS lookups.
Determine listing type: RATS-Dyna or RATS-NoPtr, as this indicates the potential root cause.
Check mail logs: Look for bounce messages referencing SpamRats or increased rejections.
Scan for malware: Ensure no compromised systems are sending unauthorized email from your IP.
Implementing solutions
Fix reverse DNS: Ensure your IP has a valid and correctly configured PTR record if listed on RATS-NoPtr.
Secure your systems: Address any compromises, close open relays, and harden your mail server security.
Submit delisting request: Use the official SpamRats website to request removal once issues are resolved.
Preventing blacklist listings, including on SpamRats, comes down to fundamental email deliverability best practices. Maintaining a strong sender reputation is paramount. This involves consistent email volume, low bounce rates, minimal spam complaints, and adherence to email authentication standards.
Proper email authentication, specifically SPF, DKIM, and DMARC, is essential. These protocols help mailbox providers verify that your emails are legitimate and originate from authorized sources. A lack of proper authentication can raise red flags and contribute to a poor sender reputation, even if you’re not intentionally sending spam.
Regularly monitoring your IP and domain reputation across various blacklists is a proactive measure that can help you catch and address issues before they significantly impact your deliverability. Being listed on any blacklist, even a less impactful one like SpamRats, should prompt an investigation into your sending practices and infrastructure security.
Key practices for sustained deliverability
Maintain clean lists: Regularly remove inactive subscribers and avoid sending to old or purchased lists to minimize spam complaints and spam traps.
Implement strong authentication: Ensure your domains have valid SPF, DKIM, and DMARC records properly configured.
Monitor server security: Regularly audit your mail servers for vulnerabilities, open relays, or signs of compromise.
Maintain positive engagement: Send relevant content to engaged subscribers to minimize spam reports.
Views from the trenches
Best practices
Always ensure your mail server's reverse DNS (PTR record) is correctly configured and resolves back to your sending domain.
Proactively monitor your IP addresses across various blacklists, not just SpamRats, to catch issues early.
If using a shared IP pool, be aware that reputation can be affected by other senders on that pool.
Implement and maintain robust email authentication (SPF, DKIM, DMARC) to build and protect sender trust.
Common pitfalls
Assuming a minor blacklist listing has no impact, leading to ignored underlying issues like malware or misconfigurations.
Attempting to delist an IP without addressing the root cause, resulting in re-listings.
Sending emails from dynamic IP addresses or consumer ISP connections for bulk or transactional mail.
Not having proper reverse DNS records for your mail server, which can trigger listings on certain blacklists.
Expert tips
Consider segmenting your email traffic. For example, transactional emails might use a different IP than marketing emails.
Regularly sweep your network for compromised machines that might be sending spam without your knowledge.
Work closely with your hosting provider if you suspect shared IP issues or need help with reverse DNS configuration.
For persistent issues, sometimes switching to a reputable third-party email service provider can alleviate deliverability challenges.
Expert view
Expert from Email Geeks says SpamRats (RATS-Dyna) is typically not particularly relevant for dedicated, static IP addresses that have proper reverse DNS. Its focus is often on dynamic IPs or consumer pools that shouldn't be sending SMTP traffic, which indicates malware.
2023-01-15 - Email Geeks
Marketer view
Marketer from Email Geeks says they were surprised to find their organizational domain's IP listed on SpamRats, having never heard of it before. It turned out to be the IP that the A record pointed to, not the domain itself.
2023-03-20 - Email Geeks
Key takeaways
While SpamRats might not be at the top of every mail server's blacklist priority list, a listing on it should never be completely ignored. It serves as a diagnostic signal, prompting you to review your email sending infrastructure and practices. Addressing any underlying issues, such as compromised systems, open relays, or misconfigured DNS, is crucial not only for delisting from SpamRats but also for maintaining overall positive sender reputation and ensuring robust email deliverability.
Proactive monitoring and adherence to best practices, including proper authentication and list hygiene, are your strongest defenses against any blacklisting. By understanding the nuances of different blacklists (or blocklists) like SpamRats, you can make informed decisions and take effective steps to keep your emails landing in the inbox.
Spamhaus
0Spam
Cisco
NoSolicitado
URIBL
abuse.ro
ALPHANET
Anonmails
Ascams
BLOCKEDSERVERS
Calivent Networks
EFnet
JustSpam
Kempt.net
NordSpam
RV-SOFT Technology
Scientific Spam
Spamikaze
SpamRATS
SPFBL
Suomispam
System 5 Hosting
Team Cymru
Validity
www.blocklist.de Fail2Ban-Reporting Service
ZapBL
2stepback.dk
Fayntic Services
ORB UK
technoirc.org
TechTheft
Regularly remove inactive subscribers and avoid sending to old or purchased lists to minimize spam complaints and spam traps.
