Deliverability

What is an email blacklist, and how do you know if you're on one?

Inboxlogy6 min readUpdated 2026-10-26

In short: An email blacklist (or DNSBL) is a public list of IP addresses and domains known for sending spam. Mailbox providers check these lists before accepting mail, so being listed can send your email straight to spam or get it rejected. Check your status against major lists with the free Blacklist Checker.

On this page

  1. What is a blacklist?
  2. How do you end up on a blacklist?
  3. What listing does to deliverability
  4. How to check and get delisted

What is a blacklist?

A blacklist, more precisely a DNSBL (DNS-based blocklist), is a public database of IPs and domains flagged for spam or abuse. Operators like Spamhaus, Barracuda and SpamCop maintain them. When a mailbox provider receives mail, it queries these lists in milliseconds. If your sending IP or domain is listed, that is a strong negative signal that hurts or blocks delivery.

Key point: Blacklists check the sending IP and domain, not the content. You can write a perfect email and still be filtered if the IP you send from is listed, which is why shared sending infrastructure carries real risk.

How do you end up on a blacklist?

Common causes: sending to spam traps (old or purchased addresses), high bounce rates from unverified lists, sudden volume spikes from a cold IP, recipient spam complaints, or sharing an IP with other senders who did any of these. For cold email, the usual culprits are buying lists and ramping volume too fast on a fresh domain.

What listing does to deliverability

Impact depends on the list. The big ones (such as Spamhaus) are used almost universally, so a listing there can tank delivery across providers. Smaller or niche lists have narrower effect. Either way, being listed means some portion of your mail is being filtered or rejected, often silently, which is why checking proactively matters.

How to check and get delisted

Run your IP or domain through the Blacklist Checker to see which lists flag you. If you are listed, each operator has a delisting process: fix the underlying cause first (stop the bad sending, clean your list, slow your ramp), then request removal through that list's website. Delisting without fixing the cause just gets you relisted.

Check your blacklist status free

See whether your IP or domain is listed on major DNSBLs like Spamhaus, Barracuda and SpamCop.

Open the Blacklist Checker →All free tools

Frequently asked questions

How do I check if my IP is blacklisted?
Enter your sending IP or domain into a blacklist checker. It queries major DNSBLs like Spamhaus, Barracuda and SpamCop and reports which, if any, list you.
How do I get removed from a blacklist?
First fix the cause (stop bad sending, clean your list, slow your warm-up). Then use the delisting form on that blacklist's website. Removing the listing without fixing the behaviour usually leads to relisting.
Why am I blacklisted when I didn't spam?
Often because you share a sending IP with others who did, or you hit a spam trap or bounced heavily from an unverified list. Dedicated infrastructure and clean lists reduce this risk.
Do all blacklists matter equally?
No. Major lists like Spamhaus are used by most providers and have broad impact. Smaller niche lists affect fewer receivers. A checker shows which lists flag you so you can prioritise.

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