Blacklist Check Tool
Look up any IP or domain across a curated panel of real-time blacklists (DNSBLs). Clear results, no signup.
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How to read the results
Safe
No issues detected across the checks we ran. You can typically proceed normally.
Warning
Something looks off. Verify additional details before sharing data or making payments.
Flagged
Strong signals of risk. Avoid interacting until the issue is investigated and resolved.
What this tool does
DNSBLs are lists used by mail servers and security tools to filter spam and abusive senders. A single listing can damage email deliverability and online reputation.
We query the major lists in parallel and show you exactly which ones returned a hit, with the response code from each.
When to use it
- Email is bouncing or going to spam
- After a server compromise or password leak
- Auditing a new IP, sender, or relay
- Investigating a suspicious inbound domain
Be alerted if you get listed
Recheck continuously and catch the first listing.
Continuous monitoring keeps results accurate over time. Track multiple domains and get alerts on changes.
Related verification steps
Key terms, defined
- DNSBL / RBL
- DNS-based blacklist. A queryable database of IPs or domains flagged for spam, abuse, or malicious activity.
- Spamhaus ZEN
- Aggregate of Spamhaus's SBL, XBL, and PBL zones. The single most consequential reputation list for global email delivery.
- URIBL / SURBL
- URI/domain blacklists that flag domains appearing inside spam message bodies, not just sender IPs.
- Spam trap
- A mailbox that should receive no legitimate mail. Hits indicate leaked list scraping, dictionary attacks, or stale CRM data and quickly damage sender reputation.
- Open relay
- An SMTP server that accepts mail from any sender to any recipient. Open relays are abused for spam within hours of discovery and trigger immediate blacklisting.
- Sender reputation
- Composite score derived from DNSBL listings, complaint rate, authentication results, engagement, and historical sending behavior.
- SPF / DKIM / DMARC
- Email authentication stack: SPF authorizes sending IPs, DKIM cryptographically signs messages, DMARC tells receivers what to do with failures and how to report them.
- Delisting
- Process of removing an IP or domain from a blacklist after the root cause is fixed. Some lists auto-expire; others require manual request.
Frequently asked questions
DNSBLs, sender reputation, and email authentication — the vocabulary mail receivers use to decide whether to deliver, defer, or drop your traffic.
What is a DNSBL?+
A DNSBL (DNS-based blacklist, also called RBL) is a real-time list of IP addresses or domains associated with spam, abuse, malware, or compromised infrastructure. Mail servers and security gateways query DNSBLs over DNS — a positive response means the asset is currently listed.
What is the difference between Spamhaus, SpamCop, Barracuda, and SORBS?+
Spamhaus ZEN is the most influential — listings there meaningfully damage deliverability worldwide. SpamCop is user-report-driven and tends to list aggressively but expire fast. Barracuda powers many enterprise mail gateways. SORBS covers multiple categories including dynamic IPs and exploited hosts. A listing on any major DNSBL warrants action.
Why am I on a blacklist?+
Common causes: a compromised mailbox sending spam, a misconfigured SMTP relay, sharing a /24 with an abusive neighbor, sending high volume from a freshly warmed IP, or hitting spam-trap addresses. Always investigate before requesting delisting — most lists require root-cause remediation.
How do I get delisted?+
Identify and stop the underlying issue (close the open relay, reset compromised credentials, fix SPF/DKIM/DMARC), then submit a delisting request through the list operator's portal. Spamhaus and Barracuda offer self-service delisting; some lists auto-expire after a clean window.
Are DNSBL listings the same as malware blocklists?+
No. DNSBLs primarily target email-sender reputation. Malware blocklists (Google Safe Browsing, PhishTank, OpenPhish) target URLs and domains that host or distribute malicious content. A site can be clean for email yet blocked in browsers, and vice versa.
How often should I check my IPs and domains?+
Manually weekly is reasonable for low-volume senders. Production mail infrastructure should be monitored continuously — most listings are detected by recipients before the sender notices, costing real deliverability while you investigate.