What is a DNS blacklist?

A DNS blacklist (DNSBL) is a real-time database of IP addresses or domains known to send spam. Mail servers query these lists before accepting email, and a listing causes your email to be rejected or junked.

How do I get removed from a blacklist?

Each blacklist has its own delist process. Click the delist link next to any listing shown in results. Fix the underlying issue first (compromised server, open relay, spam complaints) or you will be re-listed.

Which blacklists matter most?

Spamhaus ZEN, SpamCop, Barracuda, and SURBL have the widest adoption. A listing on Spamhaus ZEN will affect delivery to most major ISPs.

How often should I check?

Check weekly if you send high-volume email, or any time you notice a sudden drop in deliverability or open rates.

Free Tool

Email Blacklist Checker

Check your domain or IP against 30+ major DNS blacklists instantly. Find listings and get direct delist links.

What are DNS blacklists and why do they matter?

A DNS-based Blackhole List (DNSBL) is a real-time database of IP addresses and domains associated with spam, malware, or abusive mail behaviour. Mail servers worldwide query these lists before accepting or delivering email. If your IP or domain appears in a major DNSBL, your messages will be rejected outright or silently dropped into spam — often before recipients ever see them.

Even legitimate senders get listed. A compromised server, a misconfigured relay, a spike in bounce rates, or high complaint rates from a cold outreach campaign can all trigger a listing. Most listings are temporary and most lists provide a self-service delist path once the underlying issue is resolved.

The most impactful blacklists

Spamhaus ZEN is the single most important list — a composite of SBL (known spammers), XBL (exploited machines and botnets), and PBL (dynamic IP ranges). A Spamhaus listing affects delivery to virtually every major ISP. SpamCop aggregates user-reported spam and is widely used by ISPs. Barracuda is built into appliances deployed at thousands of enterprises. SURBL focuses on URIs found in spam bodies rather than sending IPs.

How to get delisted

First fix the root cause — a compromised server, an open relay, or a list with high complaint rates. Then visit the delist link for each listing shown above and follow the provider's removal process. Spamhaus and SpamCop typically process requests within 24 hours. Barracuda is usually instant. Never request removal before fixing the issue or you will be re-listed within days.

Preventing future listings

Implement proper email authentication: DKIM signing, a strict SPF record, and a DMARC policy of at least p=quarantine. Monitor bounce rates and complaint rates through your ESP dashboard. Set up DMARC aggregate reporting so you receive weekly XML reports of authentication failures. Clean your lists regularly and honour unsubscribes immediately.

Frequently asked questions

Does a listing on an obscure DNSBL actually hurt delivery?

The big four (Spamhaus, SpamCop, Barracuda, SURBL) account for the vast majority of rejections. Listings on smaller lists may have little practical impact individually, but they can compound reputation signals.

My IP is on the Spamhaus PBL — is that a problem?

PBL lists dynamic/residential IP ranges that should not send email directly. If you use a dedicated static IP, contact your ISP to have it removed from PBL. If you send from a residential IP, route mail through a proper relay or ESP.

How long does a listing last?

It varies. SpamCop listings expire automatically after 24 hours if no new spam is reported. Spamhaus SBL listings persist until you request removal. Barracuda listings are usually permanent until you self-delist via their portal.

Can I check a shared IP from a cloud provider?

Yes — paste the IP into the tool. Cloud IPs are frequent listing targets because they are shared across many tenants. If you are on a shared IP with your ESP, ask them to move you to a dedicated sending IP.