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Free Email Blacklist Checker

Enter an IP address or sending domain to check it against 5 major DNS-based blacklists — Spamhaus, SORBS, Barracuda, SpamCop, and CBL — instantly and for free.

What this tool checks

The blacklist checker queries five of the most widely-used DNS-based blacklists (DNSBLs). Mail servers around the world consult these lists before accepting inbound email — if your sending IP or domain appears on any of them, your messages are far more likely to be rejected or marked as spam.

BlacklistFocus
Spamhaus ZENCombined SBL + XBL + PBL — the most authoritative spam IP list globally
SORBSSpam and open relay blocking, broad coverage
BarracudaUsed by Barracuda Networks mail appliances worldwide
SpamCopUser-reported spam sources, high-volume spammer focus
CBL (Abuseat)Composite Blocking List — hijacked/infected hosts sending spam

Why it matters

  • Diagnose delivery failures — a single DNSBL listing can silently blackhole your entire campaign.
  • Monitor new IPs before sending — newly provisioned cloud IPs are often pre-listed; check before warming up.
  • Confirm delisting success — verify your removal request actually worked.

Usage limits

10 checks per minute per IP, no account required. Results cached for 5 minutes. Only public IPv4 addresses can be checked.

Need continuous deliverability monitoring checks?

Upload a list of 100k addresses and get confidence-scored results in minutes. REST API, webhooks, CSV export.

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FAQ

Your IP is reversed (e.g. 1.2.3.4 becomes 4.3.2.1), then appended to the DNSBL hostname. If the resulting domain resolves, you're listed. This is a standard DNS query — fast and requiring no credentials.

Each blacklist has its own delisting process. Visit the blacklist's website, look up your IP, and follow their removal instructions. Spamhaus is the most impactful and offers self-service delisting for some listings.

Some blacklists index domains directly (the domain in your From: or HELO). Others index the sending IP. It's best practice to check both.

Results are cached for 5 minutes to avoid hammering the DNSBL servers. For real-time monitoring, use our API.
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