Security · 10 min read · May 5, 2026 · IPLocatorTools

How to Check If Your IP Address is Blacklisted (Step-by-Step)

A blacklisted IP can silently block your emails and harm your online reputation. Here's exactly how to check, why IPs get listed, and how to get removed.

A blacklisted IP address can silently cause your emails to be rejected, prevent you from accessing certain services, and harm your online reputation — all without any obvious error message explaining why. If you are experiencing unexplained email delivery failures or connectivity issues, checking whether your IP is on a blacklist is one of the first things you should do.

The fastest way to check is to use the IP Blacklist Checker at IPLocatorTools. Enter your IP address and the tool checks it against six major DNSBL databases in seconds.

What is an IP Blacklist?

An IP blacklist (also called a DNSBL — DNS-based Blackhole List, or RBL — Real-time Blackhole List) is a database of IP addresses that have been identified as sources of spam, malware, phishing, or other malicious activity.

Email servers, network security appliances, and web application firewalls query these lists in real time when they receive incoming connections. If the connecting IP is listed, the system can reject the connection, reject the email, flag the message as spam, or subject it to additional scrutiny.

The blacklist ecosystem is distributed — there are dozens of major blacklists and hundreds of minor ones, each maintained by different organisations with different criteria for listing and removal. Some focus exclusively on email spam. Others cover botnet-controlled IPs, open proxies, exploited servers, or IPs associated with data breaches.

The Six Major Blacklists to Check

1. Spamhaus (ZEN)

Spamhaus is the most widely used and most respected blacklist in the world. The Spamhaus ZEN Block List is a composite list that combines several Spamhaus lists:

• SBL (Spamhaus Block List) — IP addresses directly controlled by spam operations
• XBL (Exploits Block List) — IPs infected with malware, operating as open proxies, or part of botnets
• PBL (Policy Block List) — Dynamic residential IP ranges that should not be sending email directly (they should use their ISP's mail server)

Being on the Spamhaus ZEN list means your email will be rejected by a very large portion of mail servers worldwide. Many organisations consider Spamhaus listing alone sufficient reason to block all traffic from an IP.

2. SpamCop

SpamCop is an email spam reporting service where recipients can report spam emails. SpamCop analyses the reported spam, traces the sending IP, and lists IPs with recent confirmed spam reports.

SpamCop listings are time-limited — they automatically expire after 24 hours if no new reports are received from that IP. This makes SpamCop more dynamic than Spamhaus but also means legitimate IPs can get temporarily listed if a brief spam incident occurs.

3. SORBS (Spam and Open Relay Blocking System)

SORBS maintains multiple sub-lists covering different categories of problematic IP behaviour: spam sources, open SMTP relays, open proxy servers, compromised hosts, and dialup/dynamic IP ranges. SORBS is particularly known for being aggressive in its listings and slow in its delisting process.

4. Barracuda Reputation Block List (BRBL)

Barracuda Networks is a major email security company, and their reputation block list is integrated into Barracuda email security appliances deployed at thousands of organisations worldwide. The BRBL focuses on IP addresses with a history of sending spam email. Barracuda offers a self-service removal tool for listed IPs.

5. UCEProtect

UCEProtect (Unsolicited Commercial Email Protection) maintains lists at three levels:

• Level 1 — Individual IPs sending spam
• Level 2 — Entire IP ranges with a high proportion of spamming IPs
• Level 3 — Entire ASNs (Autonomous System Numbers — entire ISPs or networks) with widespread spam problems

Level 2 and 3 listings can affect many innocent IPs because they target ranges and networks rather than individual addresses.

6. AbuseCBL (Composite Blocking List)

The AbuseCBL tracks IP addresses that have been observed making connections that are characteristics of infected or compromised machines — spam relay attempts, botnet command-and-control connections, and similar indicators. Unlike spam report-based lists, CBL uses technical detection rather than reports.

Step-by-Step: How to Check Your IP

Step 1 — Find your public IP address

If you do not know your current public IP address, visit IPLocatorTools and it is shown automatically on the page.

Step 2 — Run the blacklist check

Go to IPLocatorTools Blacklist Checker, enter your IP address, and click Check Blacklists. The tool queries all six major blacklists simultaneously and shows the result for each.

Step 3 — Read the results

Each blacklist will show either:

• ✅ Clean — Your IP is not listed on this blacklist
• ❌ Listed — Your IP appears on this blacklist, along with the reason if available

Step 4 — If listed, identify the reason

Each blacklist provides a reason code or description when an IP is listed. Common reasons:

• Spam sending (direct spam from the IP)
• Open relay (your mail server forwards email for any sender, allowing spam abuse)
• Open proxy (your server accepts proxy requests from anyone)
• Botnet/malware (your IP has been observed making botnet-characteristic connections)
• Policy violation (dynamic IP in a range that should not send direct email)

Why IP Addresses Get Blacklisted

Malware and Compromised Devices

The most common cause of unexpected blacklisting. If a device on your network (computer, server, NAS, IoT device, router) is infected with malware, it may silently send spam emails or connect to botnet command-and-control servers without you knowing. From the outside, this traffic appears to come from your IP address.

Signs of a compromised device: unusual network activity at odd hours, slow device performance, unusually high bandwidth usage, or your ISP contacting you about abuse complaints.

Misconfigured Mail Server (Open Relay)

If you run your own mail server and it is configured as an open relay — accepting and forwarding email from any sender, not just your own domain — spam operators will find it and use it to send millions of spam emails through your server. This will result in rapid blacklisting across all major lists.

Fix: configure your mail server to only accept email from authenticated users or from your own domain. Test your configuration at mxtoolbox.com's open relay checker.

Shared Hosting and Shared IP Addresses

If you are on a shared hosting plan, your website shares an IP address with other websites. If one of those neighbouring websites sends spam or engages in abusive activity, your shared IP may be blacklisted even though you did nothing wrong. This is one of the hidden costs of cheap shared hosting.

Solution: move to a VPS or dedicated server with your own dedicated IP address, or use a reputable hosting provider that monitors for abuse and removes offenders quickly.

Dynamic IP Address Inheritance

ISPs use pools of dynamic IP addresses. When you disconnect and reconnect, you may get an IP that was previously assigned to another customer who was sending spam. The IP is listed from their activity, and now you have it.

This is especially common with residential broadband. Many major blacklists maintain "PBL" (Policy Block Lists) that list entire ranges of dynamic residential IPs on principle — these ranges are not expected to send email directly. This is not a negative reflection on you specifically.

ISP Range Listing (UCEProtect Level 2/3)

If many customers of your ISP send spam, UCEProtect may list the entire ISP's IP range at Level 2 or 3. This affects all customers, including innocent ones. This is controversial but legal, and it forces ISPs to take abuse seriously.

If you are affected by a range-level listing, your only options are to contact your ISP's abuse team, use a reputable email relay service (SendGrid, Mailgun, Amazon SES) to send your emails through, or switch to a different ISP with better IP reputation.

How to Get Your IP Removed from Blacklists

Each blacklist has its own removal process. Here is the process for each major list:

Spamhaus Removal

1. Go to spamhaus.org/lookup/ and enter your IP address
2. The results show which specific Spamhaus list you are on and the reason
3. SBL listings — These require manual review. Fix the underlying issue (remove malware, stop spamming), then fill out Spamhaus's removal request form with an explanation
4. XBL listings — Usually requires cleaning the compromised device. Once the botnet/malware activity stops, automatic removal typically occurs within 24–48 hours. You can also submit a manual removal request
5. PBL listings — If your IP is incorrectly listed (e.g., it is a static business IP, not a dynamic residential IP), complete the PBL removal form. If it is a legitimate dynamic residential IP in a PBL range, configure your email client to use your ISP's outgoing mail server instead

SpamCop Removal

SpamCop listings expire automatically within 24 hours if no new spam reports are received from your IP. Focus on stopping whatever was generating the spam reports. If the issue is fixed, the listing will clear by itself. There is no manual removal process for SpamCop.

Barracuda Removal

1. Go to barracudacentral.org/lookups
2. Enter your IP and check the listing status and reason
3. Use the "Request Removal" form on the same page
4. Provide your email address and a brief explanation of the issue
5. Barracuda typically processes removal requests within 12–24 hours

SORBS Removal

SORBS has a self-service removal process through their website, but it requires creating an account and can be bureaucratic. Listings require a verified reason for removal. For dynamic IP listings, SORBS sometimes offers removal in exchange for a donation to charity — this is controversial but it is the official process.

UCEProtect Removal

UCEProtect Level 1 listings have an automated removal system. Level 2 and 3 listings are range-based and the only solution is for the entire ISP to clean up its act, or to use an IP from a different ISP/range.

AbuseCBL Removal

Go to abuseat.org and enter your IP. If listed, the site explains what was detected and provides an automated removal link. You must investigate and stop the malicious traffic before the removal will be processed.

Preventing Future Blacklisting

Keep all software up to date — Malware often exploits known vulnerabilities in outdated software. Operating system updates, router firmware updates, and application patches close these vulnerabilities.

Use strong, unique passwords — Compromised credentials are a common way attackers gain access to servers and use them for spam sending. Use a password manager and enable two-factor authentication everywhere possible.

Monitor outbound email volume — If you run a mail server, set up monitoring for unusual spikes in outbound email volume. A sudden increase is a sign that something is using your server to send spam.

Use SPF, DKIM, and DMARC — Configure these email authentication records in your DNS. They prevent your domain from being used in spoofed spam, which can sometimes cause your IP to be associated with spam even if your server is not sending it. Use the DNS Lookup tool to verify your TXT records include valid SPF and DKIM entries.

Choose quality hosting providers — Reputable hosting companies actively monitor for abusive activity and quickly remove customers who violate their terms. This keeps their IP ranges clean and reduces the risk of range-based listings affecting you.

Monitor your IP reputation regularly — Use the Blacklist Checker monthly for any IP addresses you use for email sending. Catching a listing early means fewer emails affected and faster recovery.

Impact of Blacklisting on Email Deliverability

A single Spamhaus listing can cause your emails to be rejected by the majority of corporate email servers worldwide. The impact varies by list:

| Blacklist | Industry adoption | Typical impact | |-----------|------------------|----------------| | Spamhaus ZEN | Very high (80%+ of mail servers) | Severe — widespread rejection | | SpamCop | Moderate (25–40%) | Moderate — some providers reject, others flag as spam | | Barracuda | Moderate (20–30%, mostly SMB) | Moderate | | SORBS | Low-moderate (10–20%) | Low-moderate | | UCEProtect L1 | Low (5–15%) | Low | | AbuseCBL | Moderate (used by many filters) | Moderate |

Even being listed on a lower-tier blacklist can cause significant problems if the recipient uses it. Enterprise email security systems often query multiple lists and use scoring — a single low-tier listing might add spam score points that push a borderline email into the spam folder.

Frequently Asked Questions

My IP is not listed but my emails still go to spam — why? IP reputation is just one factor in spam filtering. Other factors include: your domain reputation, SPF/DKIM/DMARC configuration, email content (spammy words or excessive links), recipient engagement rates, sending volume spikes, and whether you are on a shared IP with bad history. Use the DNS Lookup tool to check your SPF and DKIM TXT records.

How long does it take to get removed from a blacklist? Varies by list. SpamCop clears automatically in 24 hours. Barracuda typically processes requests within 12–24 hours. Spamhaus can take days for SBL listings and requires verifying the issue is fixed. SORBS can take weeks. UCEProtect level 2/3 depends on the entire ISP cleaning up.

My website is also affected, not just email — is that from blacklisting? Probably not from a DNSBL blacklist specifically. DNSBL blacklists are primarily used by mail servers. Website access issues are more likely caused by a separate system — Google Safe Browsing, browser security warnings, or a Web Application Firewall (WAF) block. Check your site at Google's Transparency Report (transparencyreport.google.com) for malware flags.

Can I prevent my IP from ever being blacklisted? Not with 100% certainty, because range-based listings and inherited dynamic IPs are outside your control. But you can minimise the risk: keep systems patched, monitor for malware, configure email authentication, and use quality hosting providers.

Related Tools

Check your IP reputation instantly with the IP Blacklist Checker. Use the DNS Lookup tool to verify SPF, DKIM, and MX records for your domain. See your current IP address and ISP using the IP Lookup tool. Check your domain's SSL certificate status with the SSL Checker.