Email Blacklist Directory: Every Major Blacklist Explained

If your emails are landing in spam or getting rejected outright, there is a good chance your IP address or domain appears on an email blacklist. The problem is that there are dozens of blacklists out there, each with its own criteria, its own removal process, and its own level of impact on your deliverability. Some are critical to worry about. Others barely matter.

This directory covers every major email blacklist you need to know about. For each one, you will learn what it tracks, what gets you listed, and how to get removed. Where we have a full guide, we link to it so you can dig deeper.

If you are not sure where to start, run a free blacklist check on your sending IP or domain first. That will tell you exactly which lists you are on so you can focus your efforts.

How Email Blacklists Work

Before diving into individual blacklists, it helps to understand the basics. Email blacklists — also called blocklists or DNSBLs — are databases of IP addresses and domains that have been flagged for sending spam or other unwanted email. When a mail server receives an incoming message, it checks the sender's IP or domain against one or more of these lists. If there is a match, the message gets blocked or routed to spam.

Different blacklists use different methods to detect bad senders. Some rely on spam traps (email addresses that should never receive legitimate mail). Others analyze sending patterns, volume spikes, or user complaints. A few are manually curated. The criteria and severity vary widely, which is why understanding each blacklist individually matters.

For a broader overview of how blacklisting works, see our email blacklists guide. If you want to understand the role your sending IP plays, check out our IP & domain reputation guide.

Spamhaus

Spamhaus is the single most influential email blacklist in the world. It is used by the majority of internet service providers, email hosting companies, and enterprise mail servers. If you are on a Spamhaus list, a large percentage of your email simply will not be delivered.

What Spamhaus Tracks

Spamhaus operates several lists under one umbrella. The Spamhaus Block List (SBL) targets IP addresses that are sources of spam or are controlled by known spam operations. The Exploits Block List (XBL) covers compromised machines — servers with malware, open proxies, or other vulnerabilities being exploited to send spam. The Policy Block List (PBL) flags IP ranges that should not be sending email directly, like residential broadband addresses.

For domain-based filtering, there is the Domain Block List (DBL), which flags domains found in the body or headers of spam messages.

What Triggers a Spamhaus Listing

Sending unsolicited bulk email is the most common trigger. Hitting Spamhaus spam traps is another. If your server is compromised and sending spam without your knowledge, that will land you on the XBL. Hosting on an IP range with a poor history can put you on the SBL even if you personally have not done anything wrong. The PBL listing is not punishment — it simply means your IP type is not meant for direct mail delivery, and you should route through your ISP's mail server or a dedicated email service.

How to Get Removed

Spamhaus provides a self-service removal tool via the Spamhaus Blocklist Removal Center. For SBL listings, you will need to fix the underlying problem (stop the spam, clean up your list, secure your server) and then request removal. XBL removals are automatic once the compromised behavior stops, but you can also request manual removal after fixing the issue. PBL removals require you to demonstrate that your IP should be sending email directly.

Spamhaus takes abuse seriously. If you request removal without fixing the root cause, you will be relisted quickly and future removal requests become harder.

Read our full guide: Understanding Spamhaus

Barracuda (BRBL)

The Barracuda Reputation Block List is maintained by Barracuda Central, one of the largest email security companies in the world. Their hardware appliances and cloud filtering services protect hundreds of thousands of organizations, particularly small and mid-size businesses. A listing on BRBL means your emails are being blocked across a significant swath of business recipients.

What Triggers a Barracuda Listing

Barracuda builds its blacklist from data collected across its entire network of appliances and cloud services. If Barracuda customers report your email as spam, or if your IP hits one of Barracuda's spam traps, you will end up on BRBL. High complaint rates, sudden volume spikes, and sending to outdated or purchased lists are all common triggers. Barracuda also factors in the overall sending reputation of your IP address.

How to Get Removed

Barracuda offers a free removal request form on their website. You fill out the form with your IP address and a brief explanation of what you have done to fix the problem. Removal is typically processed within 12 to 24 hours. However, if the spam behavior continues after removal, you will be relisted and subsequent requests may be scrutinized more heavily.

The key to staying off Barracuda's list is maintaining clean sending practices: authenticated email (SPF, DKIM, DMARC), opt-in-only lists, and regular list hygiene.

Read our full guide: Barracuda Blacklist

SpamCop

SpamCop is one of the oldest and most well-known spam reporting services. It is both a reporting tool that individual users can use to report spam and a blacklist (the SpamCop Blocking List, or SCBL) that mail servers query to filter incoming messages. SpamCop is now operated by Cisco as part of Cisco Talos Intelligence.

What Triggers a SpamCop Listing

SpamCop listings are driven primarily by user reports. When someone receives an unwanted email and reports it through SpamCop, the sending IP gets flagged. SpamCop also operates its own network of spam traps. Listings are time-based — they expire automatically if no new reports come in. A single report might trigger a brief listing, while repeated reports lead to longer ones.

This time-based approach means SpamCop is more reactive and shorter-lived than something like Spamhaus. But it also means that if you have an ongoing spam complaint problem, you will stay listed indefinitely.

How to Get Removed

You cannot manually request removal from SpamCop. Listings expire on their own, typically within 24 to 48 hours after the last report. The only way to get delisted is to stop generating complaints. That means fixing whatever is causing people to report your email: remove unengaged subscribers, honor unsubscribe requests immediately, and make sure your content is genuinely wanted by your recipients.

Read our full guide: SpamCop Guide

AOL Blacklist

AOL (now part of Yahoo/Verizon Media) still maintains its own internal email filtering and blacklisting systems. While AOL's email user base has shrunk from its peak, millions of people still use AOL Mail — particularly older demographics in the United States. If your business communicates with consumers, you likely have AOL addresses on your list.

What Triggers an AOL Listing

AOL tracks spam complaints from its users through a feedback loop. If too many AOL users mark your email as spam, your sending IP gets throttled or blocked. AOL also monitors for spam trap hits, authentication failures, and sending patterns that look like bulk unsolicited mail. They are particularly sensitive to high complaint rates relative to your sending volume.

How to Get Removed

AOL's postmaster resources are now managed through the Yahoo Sender Hub, where you can request removal or investigate delivery issues. You will typically need to demonstrate that you have addressed the complaint source — removed the complainers from your list, improved your opt-in process, or fixed an authentication issue. The Sender Hub provides guidance on their specific requirements for bulk senders, including feedback loop enrollment.

Read our full guide: AOL Blacklist

Outlook / Microsoft (Smart Network Data Services)

Microsoft operates its own filtering infrastructure for Outlook.com, Hotmail, Live.com, and MSN Mail. Combined, these services represent one of the largest consumer email platforms in the world. Microsoft does not publish a traditional public blacklist, but they do maintain internal reputation scoring and blocking that functions the same way.

What Triggers an Outlook Listing

Microsoft uses a combination of user complaint data (via their Junk Mail Reporting Program), spam trap hits, sending volume patterns, and authentication checks. Their SmartScreen filter evaluates content, sender reputation, and recipient engagement. Low open rates, high complaint rates, and poor authentication are all signals that can get your IP blocked or your email routed to the Junk folder.

Microsoft is also known for being aggressive with throttling. Even if you are not fully blocked, you may find that your email to Outlook recipients is being delivered very slowly or intermittently.

How to Get Removed

Microsoft provides the Smart Network Data Services (SNDS) portal where you can check your IP reputation and request mitigation. You can also submit a sender support request through their postmaster tools. Removal is not guaranteed — Microsoft evaluates each request and may require you to demonstrate improved sending practices before lifting restrictions. Enrolling in their Junk Mail Reporting Program (JMRP) feedback loop is strongly recommended so you can track complaints in real time.

Read our full guide: Outlook Blacklist

Comcast Blacklist

Comcast (Xfinity) is one of the largest ISPs in the United States, and they operate their own email filtering for Comcast.net addresses. While Comcast's email user base is smaller than Gmail or Outlook, it is concentrated among US residential customers — an important audience for many businesses.

What Triggers a Comcast Listing

Comcast blocks sending IPs based on spam complaints from their users, spam trap hits, and reputation data. They are particularly strict about volume — if you suddenly start sending a high volume of email to Comcast addresses without a history of doing so, you will likely be throttled or blocked. Comcast also checks SPF and DKIM authentication and will penalize senders who fail those checks.

How to Get Removed

Comcast provides a postmaster page with a blocklist removal form. You submit your IP address, explain what caused the issue, and describe what you have done to fix it. Response times vary, but Comcast generally processes requests within a few business days. As with other ISPs, repeated offenses make future removal requests harder.

Read our full guide: Comcast Email Blacklist

URL Blacklists (SURBL, URIBL, Google Safe Browsing)

Most blacklists focus on the sending IP address, but URL blacklists take a different approach. They scan the links inside your email body and flag messages that contain domains associated with spam, phishing, or malware. Even if your sending IP has a perfect reputation, a single blacklisted URL in your email can send it straight to spam.

What Triggers a URL Blacklist Listing

URL blacklists flag domains that appear frequently in spam messages, host phishing pages, distribute malware, or redirect to known bad destinations. Using URL shorteners (like bit.ly) in bulk email is a common trigger because spammers abuse those services heavily. Linking to a domain with a poor reputation — even a legitimate third-party service — can also cause problems.

SURBL and URIBL are the two most widely used dedicated URL blacklists. Google Safe Browsing covers a broader scope, flagging URLs involved in phishing and malware distribution.

How to Get Removed

For SURBL and URIBL, you can request removal through their respective websites once the offending content or behavior has been addressed. Google Safe Browsing issues are handled through Google Search Console. The important thing is to audit every link in your outgoing email: make sure you are not linking to compromised sites, using shared URL shorteners for bulk sends, or including tracking domains with poor reputations.

Read our full guide: URL Blacklists

Other Blacklists Worth Knowing

The blacklists above are the ones with the broadest impact, but there are several others you may encounter when running an email blacklist check. Here is a quick overview of each.

SORBS (Spam and Open Relay Blocking System)

SORBS maintains multiple lists covering open relays, open proxies, spam sources, and dynamic IP ranges. It is used by some mail servers but has a smaller footprint than Spamhaus or Barracuda. Removal typically requires submitting a request and, in some cases, a small administrative fee.

UCEPROTECT

UCEPROTECT operates three levels of blacklists. Level 1 lists individual IPs, Level 2 lists entire IP ranges from providers with abuse problems, and Level 3 lists entire ASNs (autonomous system numbers). Level 1 listings expire automatically after seven days if the abusive behavior stops. Levels 2 and 3 are more controversial because they penalize entire networks rather than individual senders.

CBL (Composite Blocking List)

The CBL is maintained by Spamhaus and focuses specifically on IPs that show signs of being compromised — sending spam due to malware infections, bot activity, or open proxies. If you are on the CBL, it usually means your server or a device on your network has been compromised. The CBL provides a self-service removal tool, but the listing will return quickly if the underlying compromise is not resolved.

SURBL

SURBL (mentioned above under URL blacklists) specifically tracks domains that appear in the body of spam messages. It is queried by spam filters to evaluate message content rather than sender IP. If your domain appears on SURBL, it usually means your domain has been observed in spam body content at scale.

PSBL (Passive Spam Block List)

The PSBL lists IPs that have sent email to its spam trap network. It is less widely used than the major blacklists, but some mail administrators do reference it. Listings expire automatically, and you can request manual removal through their website.

SpamRATS

SpamRATS maintains lists of IPs on dynamic or residential ranges (RATS-Dyna), known spam sources (RATS-Spam), and IPs with no reverse DNS (RATS-NoPtr). If you are on SpamRATS, it is usually because your IP lacks proper reverse DNS configuration or is on a range not intended for outbound email. Fixing your rDNS record and using a proper mail server typically resolves the issue.

How to Prioritize Blacklist Removal

Not all blacklists carry equal weight. If you are listed on multiple blacklists simultaneously, here is how to prioritize your removal efforts.

High Priority

Spamhaus, Barracuda, and Microsoft/Outlook listings should be addressed immediately. These affect the largest number of recipients and have the most significant impact on your overall deliverability. A Spamhaus listing alone can cut your email delivery in half.

Medium Priority

SpamCop, AOL, and Comcast listings matter if you send to those audiences. SpamCop is particularly worth monitoring because it is widely referenced and its listings reflect active user complaints — a signal you should not ignore.

Lower Priority (but Still Worth Fixing)

SORBS, UCEPROTECT, PSBL, and SpamRATS have smaller footprints. You should still address these listings when you find them, but they are less likely to be the root cause of major delivery problems. Often, fixing the issues that got you on the major blacklists will resolve these listings as well.

URL Blacklists

URL blacklist listings are always worth investigating regardless of the list's size, because they affect message content reputation rather than sender reputation. A blacklisted link in your email will cause problems across all recipients, not just those using a specific blacklist.

Preventing Future Blacklist Listings

Getting removed from a blacklist is only half the battle. If you do not fix the root cause, you will end up right back where you started. Here are the fundamentals every sender should have in place.

Authenticate your email. Set up SPF, DKIM, and DMARC for every domain you send from. Authentication failures are one of the most common blacklist triggers, and they are entirely preventable.

Use confirmed opt-in. Double opt-in (where subscribers confirm their email address before being added to your list) dramatically reduces spam complaints and spam trap hits. It is the single most effective thing you can do to protect your sender reputation.

Clean your list regularly. Remove bounced addresses, unengaged subscribers, and anyone who has not opened your email in six months or more. Stale lists are full of recycled spam traps waiting to catch you.

Monitor your reputation continuously. Running a one-time blacklist check is a good start, but blacklist listings can happen at any time. Ongoing monitoring through a tool like deliverabilitychecker.com alerts you the moment a listing appears, so you can act before it impacts your campaigns.

Send consistently. Sudden spikes in volume look suspicious to blacklist operators and ISP filters alike. Ramp up gradually when increasing your sending volume, and maintain a steady cadence.

For more on how spam filters evaluate your email beyond blacklists, see our spam filtering & deliverability guide.

Keep Your Sending Reputation Clean

Email blacklists exist to protect recipients from unwanted email. The best way to stay off them is to send email that people actually want to receive. That means permission-based lists, relevant content, easy unsubscribes, and proper technical setup.

Use our free email blacklist checker to scan your IP and domain against every major blacklist in this directory. If you find a listing, follow the removal steps in the relevant guide linked above. And if you want to stop worrying about blacklists entirely, set up automated monitoring so you are always the first to know.