Blacklist Check

Check IP or domain against 100+ DNS blacklists (RBL/DNSBL). Free email blacklist checker to detect if your mail server is blocked and causing delivery issues.

Run a check to see results

APIPOST /api/v1/email/blacklist
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Try also: Email Health
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Key Features

100% Free

No registration required, unlimited checks

Instant Results

Real-time analysis with detailed output

REST API Access

Integrate into your workflow via API

Accurate Data

Live queries to authoritative sources

What is Blacklist Check?

The blacklist checker scans your IP address or domain against over 100 DNS-based blacklists (DNSBL/RBL) to detect if your mail server has been flagged for spam, abuse, or malicious activity. Being listed on even one major blacklist — such as Spamhaus, Barracuda, SORBS, or SpamCop — can cause email delivery failures, with messages bounced or silently routed to spam folders by receiving servers that consult these lists during delivery. The tool checks all major public RBLs simultaneously and reports which lists flag your IP, helping you identify and resolve the issue before it severely impacts your email deliverability.

This free email blacklist checker is essential for email administrators monitoring their mail server reputation, businesses noticing a sudden drop in email delivery rates, IT teams investigating bounce-back messages mentioning blacklists, and hosting providers auditing their IP space for abuse. Regular blacklist monitoring (weekly or after any email incident) is a best practice for maintaining a healthy sender reputation.

How to Use

  1. 1Enter the IP address or domain you want to check against blacklists
  2. 2Click 'Run Check' to scan against 100+ DNS-based blacklists (RBL/DNSBL) simultaneously
  3. 3Review the results — green means clean (not listed), red means flagged on that specific blacklist
  4. 4For any blacklist hits, note the blacklist name and check their website for details about why you were listed
  5. 5Follow the delisting process for each blacklist (usually a self-service form on their website)
  6. 6After resolving the issue, re-run the check to confirm successful delisting

Who Uses This

System Administrators

Monitor and troubleshoot infrastructure

Developers

Debug network issues and integrate via API

SEO Specialists

Verify domain configuration and performance

Security Analysts

Audit and assess network security

Frequently Asked Questions

How do I check if my IP address is blacklisted?
Enter your mail server's IP address or your domain name in the Blacklist Check tool and click Run Check. The tool queries over 100 DNS-based blacklists (DNSBL/RBL) simultaneously and reports which ones contain your IP. A clean result across all lists means your IP has a good reputation. Even a single listing on a major blacklist like Spamhaus or Barracuda can cause widespread email delivery failures, so take any hit seriously.
Why is my email going to spam or being rejected?
Blacklisting is one of the most common causes of email deliverability problems. Your mail server's IP may have been flagged for sending spam (even unintentionally — a compromised user account can trigger this), running an open relay that spammers exploited, being on a shared hosting IP where another tenant sent spam, generating too many bounces from sending to invalid addresses, or being part of an IP range flagged for abuse. Run a blacklist check first — if your IP is listed, that's likely the primary cause. If your IP is clean, investigate SPF, DKIM, and DMARC configuration instead.
How do I get removed from a blacklist?
Each blacklist has its own delisting process: Spamhaus has a self-service removal form at their website where you can request delisting after fixing the issue. Barracuda requires registration at their removal portal. SORBS has an automated expiry after the abuse stops. SpamCop listings expire automatically after 24-48 hours if no new spam is reported. Most blacklists require that you fix the underlying issue (close open relay, secure compromised accounts, clean malware) before or as a condition of delisting. Some automatically delist after a cool-down period if no new incidents occur. Major listings (Spamhaus SBL) may require direct communication with their abuse team.
What causes an IP to get blacklisted?
Common causes include: sending bulk unsolicited email (spam) from the IP, having a compromised email account or website that spammers use to send through your server, running an open SMTP relay that forwards email without authentication, sending to many invalid addresses (high bounce rate signals a purchased or scraped email list), being part of a botnet (malware on a machine using your IP), hosting phishing pages or malware distribution, or simply being on a shared hosting IP where another customer triggered the listing. Even legitimate senders can get blacklisted if they don't follow email best practices.
How often should I check my IP against blacklists?
Check your mail server's IP at least weekly as a routine practice. Additionally, check immediately when you notice any of these symptoms: sudden increase in email bounce rates, recipients reporting your emails going to spam, bounce messages mentioning 'blocked' or 'blacklisted', a drop in email open rates without other explanation, or after any security incident on your server. For critical email infrastructure, consider setting up automated monitoring that alerts you if your IP appears on any major blacklist — catching a listing within hours rather than days minimizes the impact on your email deliverability.

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API Endpoint

POST /api/v1/email/blacklist
View Documentation