What is a DNS blacklist (DNSBL)?

A DNSBL is a published list of IP addresses or domains that have been reported for spam or abuse, which mail servers query to decide whether to accept your messages. This tool checks your domain or IP against several of these common blocklists at once.

How do I use this tool?

Enter a domain name or an IP address and run the check; the tool queries multiple public DNSBLs server-side and reports, for each list, whether you are listed or clean. Nothing you enter is stored.

Why does being on a blacklist matter?

If your sending IP or domain is listed, receiving mail servers may reject, delay, or spam-folder your email, hurting deliverability. Checking regularly lets you catch a listing before it damages your reputation.

I'm listed. How do I read and fix the result?

The result names which blocklist flagged you, and most DNSBLs publish a lookup and delisting page for that specific IP or domain. Fix the root cause first (compromised host, open relay, or spam) then request delisting, since re-listing is likely otherwise.

Does a clean result here guarantee my mail will be delivered?

No; this tool only covers a set of common public DNSBLs, and inbox providers also use private lists, content filtering, and authentication checks like SPF, DKIM and DMARC. A clean result is a good sign but not a delivery guarantee.

Blacklist Look Up

Related tools

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What do you want to look up?

Blacklist Look Up

Looks up whether this domain's IP address (or the IP address you entered) appears on common email blacklists (DNSBL) — being listed can cause outgoing mail to be rejected or sent to spam.

Also look up blacklist status when I run this search

What this is

DNS-based blacklists (DNSBLs) enumerate IP addresses observed sending spam. Most mail providers consult several of them; being listed on a widely-used one measurably hurts delivery.

How to read your result

Clean on all zones is the goal. A single listing on an obscure list matters little; a listing on a major zone (e.g. Spamhaus) demands action. Listings apply to the IP, not the domain — shared IPs share their reputation.

Common problems and how to fix them

Listed on a major blacklist

How it shows up: Widespread bounces referencing the blacklist by name, or sudden delivery collapse to major providers.

How to fix it: First stop the cause — a compromised account, an infected machine, an open relay, or genuinely spammy sending. Then request delisting via the specific list's process (each has its own form). Delisting without fixing the cause leads to prompt relisting.

Inherited a dirty IP

How it shows up: A brand-new server is listed before you sent a single message — the previous tenant burned the address.

How to fix it: Request delisting citing new ownership, or ask the provider for a different IP. Check candidate IPs before pointing production mail at them.

Listed on tiny or pay-to-delist zones only

How it shows up: A scanner shows "listed" on lists you have never seen referenced in real bounces.

How to fix it: Verify whether real receivers actually use that list (bounce messages tell you). Ignore extortionate pay-to-delist operations; reputable lists never charge for delisting.

Frequently asked questions

What is a DNS blacklist (DNSBL)?: A DNSBL is a published list of IP addresses or domains that have been reported for spam or abuse, which mail servers query to decide whether to accept your messages. This tool checks your domain or IP against several of these common blocklists at once.
How do I use this tool?: Enter a domain name or an IP address and run the check; the tool queries multiple public DNSBLs server-side and reports, for each list, whether you are listed or clean. Nothing you enter is stored.
Why does being on a blacklist matter?: If your sending IP or domain is listed, receiving mail servers may reject, delay, or spam-folder your email, hurting deliverability. Checking regularly lets you catch a listing before it damages your reputation.
I'm listed. How do I read and fix the result?: The result names which blocklist flagged you, and most DNSBLs publish a lookup and delisting page for that specific IP or domain. Fix the root cause first (compromised host, open relay, or spam) then request delisting, since re-listing is likely otherwise.
Does a clean result here guarantee my mail will be delivered?: No; this tool only covers a set of common public DNSBLs, and inbox providers also use private lists, content filtering, and authentication checks like SPF, DKIM and DMARC. A clean result is a good sign but not a delivery guarantee.

Why it matters

Being listed on even one widely-used blacklist can cause a meaningful share of your outgoing email to be silently rejected or sent straight to spam, regardless of how well-configured your SPF, DKIM and DMARC are. Checking regularly — especially after noticing a drop in email deliverability — helps you catch a listing early and start the delisting process before it does more damage.

Examples

After migrating to a new mail server IP (especially a shared cloud IP), look it up before relying on it for production email — previous tenants can leave a bad reputation behind.
If recipients report your emails are going to spam, a blacklist look up is one of the fastest ways to rule out (or confirm) IP reputation as the cause.
Each blacklist has its own delisting process — being listed doesn't mean permanently blocked, but it does require action.