To check if your domain or IP is blacklisted, run it through a multi-blacklist checker that queries all major lists at once. If you are listed, fix the root cause first (compromised account, spoofing, bad list), then submit a removal request to the specific blacklist. Most listings are resolved within 24 to 48 hours. This guide covers which blacklists actually matter, how to check them, and the exact delisting process for each one.
Key Takeaway
- 100+ email blacklists exist, but only 3 have significant impact: Spamhaus, Barracuda, and SpamCop
- Spamhaus is the most impactful. A listing causes immediate rejection at Microsoft, Yahoo, and most enterprise mail servers
- Gmail ignores most external blacklists, relying on its own behavioral signals instead (except Spamhaus PBL for unauthorized IPs)
- Check your domain now: Email Blacklist Checker scans 100+ lists in seconds
What email blacklists are and how they work
An email blacklist (also called a blocklist or DNSBL) is a real-time database of IP addresses and domains that have been identified as sources of spam. When a mail server receives an incoming message, it queries one or more blacklists to check if the sender's IP or domain is listed. If there is a match, the message is rejected or routed to spam.
The mechanism is DNS-based, which makes it fast. The receiving server performs a DNS lookup against the blacklist's zone file. A positive response means "listed." A negative response (NXDOMAIN) means "not listed." This check adds milliseconds to the delivery process but filters out billions of spam messages daily.
Not all blacklists are created equal. Some are maintained by well-funded organizations with strict listing criteria. Others are automated with aggressive thresholds. The practical impact of a listing depends entirely on which blacklist you are on and which providers check it.
The blacklists that actually matter
There are over 100 active email blacklists. Most of them do not meaningfully affect your deliverability. The ones that do are used by the inbox providers that handle the majority of the world's email. Here are the three that matter most.
Spamhaus
The most impactful blacklist in the email ecosystemSpamhaus operates multiple lists, each targeting a different type of threat:
- SBL (Spamhaus Block List): Known spam sources, manually curated. A listing here means Spamhaus has evidence that your IP is actively sending spam.
- XBL (Exploits Block List): Compromised systems, botnets, and open proxies. If your server was hacked and is sending spam without your knowledge, it ends up here.
- PBL (Policy Block List): IP ranges that should not be sending email directly (residential IPs, dynamic ranges). This is not a "spam" listing; it is a policy listing. Gmail checks this one.
- DBL (Domain Block List): Domains (not IPs) associated with spam. Your domain can appear here even if your IP is clean.
Impact: A Spamhaus SBL or XBL listing causes 550 SMTP rejection errors at Microsoft 365, Outlook.com, Yahoo, AOL, and most enterprise mail servers. This is not spam folder placement. Your emails are rejected entirely.
Delisting: Submit a request at the Spamhaus Blocklist Removal Center. Spamhaus will deny the request if the underlying problem has not been fixed. Processing time is 24 to 48 hours. PBL listings are policy-based and generally cannot be removed unless you can prove the IP should be sending mail directly.
Barracuda (BRBL)
Widely used by enterprise and SMB mail securityThe Barracuda Reputation Block List collects data from millions of Barracuda security appliances deployed worldwide. It uses real-time analysis and machine learning to identify spam sources. Because Barracuda appliances are popular in the business market, a BRBL listing disproportionately affects B2B email delivery.
Impact: Emails rejected or filtered at organizations using Barracuda email security. Less impactful for consumer email (Gmail, Yahoo) but significant for B2B senders reaching corporate inboxes.
Delisting: Submit a removal request at barracudacentral.org. Typical response time is 12 to 24 hours. Barracuda requires you to explain what caused the listing and what steps you have taken to prevent recurrence.
SpamCop
User-reported spam with automatic expirationSpamCop maintains its blacklist based on user-submitted spam reports. When enough users report email from your IP as spam, SpamCop lists it. The listing automatically expires within 24 to 48 hours if no new reports are received. SpamCop data also feeds into other blacklists and filtering systems, amplifying its indirect impact.
Impact: Moderate. Some providers check SpamCop directly. The bigger risk is that SpamCop data contributes to listings on other systems.
Delisting: Automatic. Stop sending spam (or fix the compromise) and the listing expires in 24 to 48 hours. No manual request needed.
How each inbox provider uses blacklists
The relationship between blacklists and inbox providers is not straightforward. Each provider uses different sources and weighs them differently.
| Provider | External blacklists used | Primary filtering method | Blacklist listing impact |
|---|---|---|---|
| Gmail | Spamhaus PBL only | Internal behavioral signals, engagement data | Low (except PBL) |
| Microsoft (Outlook) | Spamhaus SBL/XBL, internal lists | IP reputation via SNDS, authentication | High (550 rejections) |
| Yahoo | Spamhaus, SpamCop | Complaint rates via feedback loop | High (550 rejections) |
| Apple (iCloud) | Spamhaus | Authentication pass rates | High |
| Enterprise (Barracuda, Proofpoint) | Spamhaus, Barracuda BRBL, SpamCop, SORBS, UCEPROTECT | Appliance-level filtering | High (550 rejections) |
The takeaway: if you are on Spamhaus, your emails are being rejected at nearly every provider except Gmail. If you are only on an obscure blacklist, the practical impact may be minimal. Focus your energy on the blacklists that your recipients' providers actually check.
How to check if your domain or IP is blacklisted
Checking is straightforward. You need to test both your domain and your sending IP address, because they are listed independently.
Run a multi-blacklist check
Use the Email Blacklist Checker to scan your domain and IP against 100+ blacklists simultaneously. This gives you a complete picture in seconds. You will see which lists you are on (if any) and links to each blacklist's lookup page for more details.
Find your sending IP
If you do not know your sending IP, check the email headers of a recent message you sent. Look for the Received: header closest to the top of the chain; it contains the originating IP. Alternatively, your email service provider's dashboard will show your sending IPs. Use the Email Header Analyzer to parse headers automatically.
Check individual blacklists directly
For the three major blacklists, you can also check directly:
- Spamhaus: check.spamhaus.org (IP and domain lookup)
- Barracuda: barracudacentral.org/lookups (IP lookup)
- SpamCop: spamcop.net/bl.shtml (IP lookup)
Run a full health check
Blacklisting is often a symptom of a deeper problem. Run a complete Domain Email Health Score check to test your authentication (SPF, DKIM, DMARC), DNS configuration, and blacklist status in one scan. If authentication is broken, fixing the blacklist alone will not solve your deliverability problem. For the full technical checklist, see How to Fix Emails Going to Spam.
Why you got blacklisted: the 5 most common causes
Before you request delisting, identify what caused the listing. Every major blacklist will re-list you if you delist without fixing the problem. Here are the five most common causes.
| Cause | How it happens | How to fix it |
|---|---|---|
| Compromised account or server | An account on your server was hacked and is sending spam without your knowledge. This is the #1 cause of XBL listings. | Change all passwords. Scan for malware. Check for unauthorized mail scripts. Review outbound mail logs for unusual volume. |
| Domain spoofing | Someone is sending spam using your domain in the From: header. Without DMARC enforcement (p=reject), receiving servers cannot distinguish spoofed mail from legitimate mail. |
Publish a DMARC record with p=reject. This tells receiving servers to reject any email failing SPF/DKIM alignment. |
| Sending to spam traps | Spam traps are email addresses operated by blacklist providers to catch bad senders. They appear in purchased lists, scraped databases, and old lists that have not been cleaned. | Remove all contacts inactive for 6+ months. Never buy or scrape lists. Use double opt-in. |
| High complaint rates | Too many recipients are marking your email as spam. Google's threshold is 0.3%; SpamCop lists based on user reports. | Add one-click unsubscribe. Honor opt-outs within 2 days. Only send to people who opted in. See the bulk sender requirements guide. |
| Open relay or misconfigured server | Your mail server is configured to relay email from any sender, allowing spammers to use it as a proxy. This is rare with modern email services but still occurs with self-hosted servers. | Configure your server to reject unauthenticated relay requests. Test with an open relay checker. |
How to get delisted: step-by-step for each major blacklist
Before you submit any removal request
Fix the underlying problem first. Every major blacklist will deny your request (or re-list you immediately) if the cause has not been addressed. Confirm that your server is no longer sending spam, is not an open relay, all compromised accounts have been secured, and your authentication records are valid.
Spamhaus delisting process
- Go to the Spamhaus Blocklist Removal Center (check.spamhaus.org)
- Enter your IP address or domain to confirm the listing and identify which list (SBL, XBL, DBL, PBL) you are on
- Click the removal request link next to the listing
- Provide a detailed explanation of what caused the issue and what corrective actions you have taken
- Include evidence: screenshots of authentication record updates, security audit results, or logs showing the spam source has been eliminated
- Submit the request. Processing takes 24 to 48 hours.
PBL listings are different. The PBL lists IP ranges that should not send email directly (residential IPs, dynamic ranges). If your IP is on the PBL, you should send email through your ISP's mail server or a legitimate email service provider, not directly from that IP. PBL removal requests are only granted if you can demonstrate the IP is a legitimate mail server.
Barracuda delisting process
- Go to barracudacentral.org/lookups and enter your IP
- If listed, click the removal request link
- Fill out the form explaining the cause and your remediation steps
- Submit. Typical response time is 12 to 24 hours.
Barracuda maintains a "poor" reputation category even after delisting if the IP has a history of problems. Consistent clean sending behavior over several weeks is required to rebuild reputation.
SpamCop delisting process
SpamCop is fully automatic. Listings expire within 24 to 48 hours if no new spam reports are received from your IP. There is no manual removal form. The only action required is to stop sending spam (or fix the compromise that is causing it). If reports keep coming in, the listing will keep renewing.
Other blacklists
| Blacklist | Delisting method | Typical timeframe |
|---|---|---|
| SORBS | Manual request via sorbs.net | 24 to 72 hours |
| UCEProtect Level 1 | Automatic after 7 days of clean behavior | 7 days (or paid express removal) |
| UCEProtect Level 2/3 | Automatic only (covers entire IP ranges, not individual IPs) | 7+ days |
| Invaluement | Manual request via invaluement.com | 24 to 48 hours |
| URIBL | Manual request via uribl.com | 48 to 72 hours |
How to prevent future blacklistings
Delisting is reactive. Prevention is what keeps you off lists permanently. These four practices cover the vast majority of cases.
- Configure authentication correctly. Publish SPF, DKIM, and DMARC records for every domain you send email from. Move DMARC to
p=rejectto prevent spoofing. Use our Email Authentication Setup Wizard for a guided walkthrough. For the full explanation of how these protocols work, read Email Authentication Explained: SPF, DKIM, and DMARC. - Keep spam complaints below 0.1%. Google's recommended threshold. Monitor via Google Postmaster Tools and provider feedback loops. Make unsubscribe easy and visible.
- Never send to purchased or scraped lists. This is the fastest path to a blacklisting. Spam traps are seeded throughout purchased databases. One send to a Spamhaus trap can get you listed immediately.
- Monitor weekly. Run the Email Blacklist Checker at least weekly, or set up automated monitoring through your email service provider. Catching a listing early limits the damage.
Blacklist check vs. full deliverability audit
A blacklist check tells you one thing: whether your IP or domain appears on a blacklist. It does not tell you whether your authentication is configured correctly, whether your reputation is healthy, or whether your content triggers spam filters.
For a complete picture, combine the blacklist check with these tools:
| Check | What it tests | Free tool |
|---|---|---|
| Blacklist status | Whether your IP/domain appears on 100+ blacklists | Blacklist Checker |
| SPF record | Validity, lookup count, authorized senders | SPF Checker |
| DKIM record | Key published, valid, correct selector | DKIM Checker |
| DMARC record | Policy, alignment, reporting configured | DMARC Analyzer |
| MX records | Mail server configuration and priority | MX Record Lookup |
| Overall health | All of the above in one scan | Email Health Score |
Frequently asked questions
How do I check if my domain or IP is on a blacklist?
Enter your domain or sending IP into a multi-blacklist checker that queries all major lists at once. The Email Blacklist Checker scans against 100+ blacklists including Spamhaus, Barracuda, SpamCop, SORBS, and dozens of regional lists. You can also query individual blacklists directly: check Spamhaus at check.spamhaus.org, Barracuda at barracudacentral.org/lookups, and SpamCop at spamcop.net/bl.shtml.
Which email blacklists actually matter?
Spamhaus is the most impactful blacklist by a wide margin. A listing on Spamhaus SBL or XBL causes immediate rejection at Microsoft 365, Outlook.com, Yahoo, AOL, and most enterprise mail servers. Barracuda BRBL is the second most impactful, widely used by businesses and SMBs running Barracuda appliances. SpamCop is the third, with listings that feed into Spamhaus and other systems. Gmail does not use external blacklists for filtering (except Spamhaus PBL for unauthorized IPs), relying instead on its own behavioral signals.
How long does it take to get delisted from an email blacklist?
Delisting timeframes vary by blacklist. SpamCop auto-delists within 24 to 48 hours if no new spam reports are received. Spamhaus processes manual removal requests within 24 to 48 hours, but will deny the request if the underlying problem has not been fixed. Barracuda typically responds within 12 to 24 hours. UCEProtect has a standard 7-day auto-removal period. The critical requirement for all blacklists: fix the root cause before requesting removal.
Can I prevent my domain from being blacklisted?
Yes. The four most effective preventive measures are: keep your spam complaint rate below 0.1% (Google's recommended threshold), configure SPF, DKIM, and DMARC correctly to prevent spoofing of your domain, never send to purchased or scraped email lists, and monitor your blacklist status weekly with automated tools. Most blacklist entries are caused by compromised accounts sending spam, spoofed domains without DMARC enforcement, or sending to old lists with spam traps. Addressing these three covers the vast majority of cases.
