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Blacklist Check

Check if an IP or domain is listed on major spam and malware DNSBLs.

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Spam & Malware DNSBL Scanner

Enter an IP address or domain to check reputation against major DNS-based blackhole lists.

Technical specification & engineering details

What this tool does

Queries major DNS-based blackhole lists (DNSBLs) — including Spamhaus, Barracuda, and SpamCop — to check whether a given IP address is currently flagged as a spam or malware source. If you enter a domain instead of an IP, it's resolved to its mail-sending IP first.

Why this matters for email deliverability

Before troubleshooting why legitimate mail is landing in spam or being rejected outright, check whether the sending IP is blacklisted — receiving mail servers routinely consult these lists and will reject or quarantine mail from a listed source regardless of how well SPF, DKIM, and DMARC are configured.

What to do if you're listed

Each DNSBL operator has its own delisting process, usually a web form on their site — search for the zone name shown in the results plus "delisting" to find it. Getting listed again after removal usually means the underlying cause (an open relay, a compromised account, or a misconfigured server sending unsolicited mail) hasn't actually been fixed.

Frequently asked questions

I'm not listed, so why is my mail still going to spam?

Blacklisting is one of many spam signals — check the Email Health tool for SPF/DKIM/DMARC configuration issues too, since receivers weigh authentication as heavily as reputation.

How many blacklists does this check?

It queries several major DNSBLs in real time (including Spamhaus and Spamcop-style lists), not just one — a single tool call covers the lists mail providers actually check most often.

I'm listed on one obscure blacklist — how urgent is this?

Not very. A listing on Spamhaus or another major list can genuinely hurt deliverability; a listing on a small or rarely-used list usually has little practical effect. Prioritize fixing the major ones first.

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