What are the best websites or tools to check IP addresses and domains for blacklists?
Matthew Whittaker
Co-founder & CTO, Suped
Published 21 Apr 2025
Updated 19 Aug 2025
8 min read
Email deliverability can be a tricky maze to navigate, and one of the biggest roadblocks we face is getting our IP addresses or domains listed on a blacklist (or blocklist). When that happens, your emails might not reach their intended recipients, getting filtered into spam folders or outright rejected. Regularly checking for these listings is a crucial step in maintaining a healthy sending reputation and ensuring your messages land in the inbox.
The good news is there are many excellent websites and tools available to help you check your IP address and domain status against various blacklists. Understanding which ones to use and why can save you a lot of headaches and keep your email program running smoothly. I will walk you through some of the most effective options and how to leverage them.
Identifying if your IP address or domain is blacklisted is a fundamental part of email deliverability. These blocklists are essentially databases of IP addresses and domains known to send spam, malware, or engage in other malicious activities. Mailbox providers consult these lists to decide whether to accept incoming mail. If you're on one, it directly impacts your ability to reach the inbox. Knowing how these lists operate, and what happens when your IP gets blocklisted or when your domain is on an email blacklist, is key to proactive management.
There are many types of email blocklists, ranging from public, widely used DNS-based blackhole lists (DNSBLs) to private, proprietary lists used by specific mailbox providers. While some tools check against a broad spectrum of public lists, others might specialize in certain types or offer deeper insights. It's often beneficial to use a combination of tools for a comprehensive view of your reputation.
The goal isn't just to check if you're on a list, but also to understand how email blacklists actually work. This knowledge empowers you to take corrective action, if needed, and implement practices that prevent future listings. Knowing what specific email blocklists are most important to monitor for deliverability issues can help you prioritize your efforts.
Free tools for quick checks
For quick, one-off checks, several free websites provide excellent services. These are great for initial investigations or routine spot-checks. My personal go-tos typically involve a few widely recognized options that scan against a comprehensive set of DNSBLs. These tools are typically very straightforward to use, requiring just your IP address or domain name to provide a report.
One popular option is MultiRBL.valli.org. It allows you to test your mail server's IP (IPv4 or IPv6) against a large number of blacklists and whitelists, providing a clear overview of your status across multiple reputable sources. Another highly regarded tool for checking if your IP address or domain is on a blacklist is the Spamhaus Lookup tool. Spamhaus maintains some of the most influential blocklists globally, so a clean report from them is a strong indicator of good standing. I often recommend that people understand how to check Spamhaus for an IP address and interpret the listings.
For a broader sweep, I find myself using tools that aggregate results from many blacklists. These provide a consolidated report, making it easier to see if you're listed anywhere. While they don't always offer the deep dive of a dedicated blacklist's own lookup tool, they are excellent for a comprehensive initial assessment. These tools effectively answer the question of what free tools can check if my IP is blacklisted.
Tool
Key feature
MXToolbox
Comprehensive checks against over 100 DNSBLs for IP and domain.
MultiRBL.valli.org
Checks IP addresses against 200+ blacklists and whitelists.
Spamhaus Lookup
Verifies IP/domain against Spamhaus's highly influential blocklists.
HetrixTools
Offers free blacklist monitoring and single checks for IPs and domains.
Beyond individual checks: proactive monitoring
While individual checks are useful, a more robust strategy involves proactive monitoring. This is where specialized services come into play. These platforms often provide continuous monitoring of your IPs and domains, alerting you immediately if a listing occurs. This real-time notification is critical, as the faster you react to a blacklist, the less impact it will have on your deliverability.
Many tools are designed specifically for blocklist monitoring and can provide automated checks and alerts. They often integrate with a wider range of blacklists, including some private ones, giving you a more complete picture of your email reputation. This type of ongoing oversight is invaluable for high-volume senders or businesses where email deliverability is mission-critical.
Choosing the best blacklist monitoring tools for senders managing multiple clients, for example, often comes down to the granularity of notifications and how frequently they perform checks. Some services offer highly customizable alert options, allowing you to receive notifications via email, text, or even integrated into collaboration tools. This means you can be notified immediately about specific blacklists that matter most to your sending infrastructure.
Reactive checking
Manual Effort: Requires you to manually visit websites and input your IP/domain.
Spot Checks: Best for occasional verification or troubleshooting specific deliverability issues.
Delayed Response: You might only discover a listing after deliverability issues have already begun.
Proactive monitoring
Automated: Tools automatically check your assets at regular intervals (e.g., every few minutes).
Continuous Oversight: Ideal for managing multiple IPs/domains and critical email programs.
Immediate Alerts: Receive instant notifications when a listing occurs, enabling rapid response.
What to do once you find a listing
Finding out your IP or domain is blacklisted is only the first step. The next crucial phase is understanding what it means when your email is blacklisted and what actions to take. Most blacklists provide a delisting process, which typically involves demonstrating that the underlying issue has been resolved. This often requires identifying the root cause of the listing, which could range from sending unsolicited emails to compromised accounts or insecure configurations. I've found that having a clear plan for delisting is just as important as the monitoring itself.
To effectively address the cause, you might need to investigate your sending practices, review your subscriber acquisition methods, or even scan your systems for vulnerabilities. For example, if your IP has been blocklisted, you'll want to understand what happens when your IP gets blocklisted and how to recover. Similarly, if your domain is listed, understanding what happens when your domain is on an email blacklist guides your recovery actions.
After you've identified and fixed the issue, you can typically request delisting directly from the blacklist provider. This process varies by list, but usually involves submitting a form or sending an email. Be prepared to explain the steps you've taken to resolve the problem. Most lists will remove you once they confirm the issue is no longer present. Consistent monitoring after delisting is vital to prevent repeat occurrences and ensure long-term email deliverability. This entire cycle is part of why your emails might go to spam.
Don't just check, act!
While checking blacklists is essential, it's merely a diagnostic step. The true value comes from quickly addressing any listings and implementing preventative measures. A listing indicates a problem with your sending practices or security, and ignoring it will lead to ongoing deliverability issues. Always investigate the root cause and take immediate action to remediate it.
Views from the trenches
Best practices
Maintain a clean email list by regularly removing inactive or invalid addresses to reduce bounces and spam complaints.
Implement robust email authentication protocols, including SPF, DKIM, and DMARC, to protect your domain from spoofing.
Monitor your sending reputation consistently through various tools and mailbox provider feedback loops.
Segment your audience and send relevant content to avoid spam complaints and maintain engagement.
Warm up new IPs or domains gradually to build a positive sending history with mailbox providers.
Common pitfalls
Ignoring small, regional blacklist listings, which can still impact deliverability to specific recipients.
Failing to address the root cause of a blacklist listing, leading to repeated listings.
Not maintaining accurate and up-to-date DNS records for your sending domains.
Sending emails to purchased or old lists, which are often full of spam traps and invalid addresses.
Neglecting to implement DMARC, SPF, and DKIM, leaving your domain vulnerable to abuse that can lead to blacklisting.
Expert tips
Use a combination of public blacklist checkers and specialized monitoring services for comprehensive coverage.
Set up automated alerts for blacklist listings to ensure immediate notification and response.
Keep detailed records of your delisting requests and communication with blacklist providers.
Regularly review your email content and sending patterns to ensure compliance with anti-spam policies.
Invest in understanding how different blacklists operate and which ones are most influential for your audience.
Marketer view
Marketer from Email Geeks says most blacklist checking sites offer similar core functionality, but the real difference lies in their notification features and how close to real-time their checks are. Customizable alerts for specific blacklists and recipient types are highly beneficial.
2019-09-15 - Email Geeks
Marketer view
Marketer from Email Geeks says they frequently use MXToolbox due to its comprehensive nature for quick checks.
2019-09-16 - Email Geeks
Maintaining a healthy email reputation
Staying on top of your IP and domain reputation is an ongoing effort that requires both reactive checking and proactive monitoring. By utilizing a combination of free individual check tools and potentially investing in a dedicated monitoring service, you can effectively track your status across various blacklists. Remember, identifying a listing is just the beginning, prompt action to address the root cause is what truly safeguards your email deliverability. This vigilant approach helps ensure your emails consistently reach the inbox.
By understanding an in-depth guide to email blocklists and consistently applying best practices, you can mitigate the risks of blacklisting and maintain a strong sending reputation, which is crucial for overall email deliverability. This proactive management prevents deliverability issues before they become major problems.
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
MXToolbox
MultiRBL.valli.org
Spamhaus Lookup
HetrixTools
