DNS Blacklist (RBL) Checker
Check an IP against the major blocklists — and see which refused to answer.
How this lookup works
A blocklist is queried by reversing the address and looking it up under the list's own domain: an answer means listed, and no such name means not listed. What most checkers miss is the third case. The major lists refuse queries that arrive through public resolvers, and Spamhaus in particular answers with a listed-looking value in the 127.255.255 range that means "your query was blocked". A checker that counts any answer as a listing reports everything as blacklisted; one that only looks for the absence of a name reports everything as clean. The second is the common failure and the more damaging one, because it is reassuring.
What the results mean
- Listed
- The list returned a code in the 127.0.0 range. Each code means something specific, and the meanings for Spamhaus are shown.
- Query refused
- The list answered in the 127.255.255 range, which means it does not accept lookups from public resolvers. Not a listing and not a clean result.
- Not listed
- No record exists for that address under the list. Genuine, for the lists that answered.
- What a listing costs
- It varies enormously. Spamhaus affects delivery almost everywhere; a listing on an aggregate list few receivers consult changes nothing.
Common problems and fixes
- Every checker says clean and my mail still bounces
- Check whether the lists that matter actually answered. A refused query counted as clean is the usual explanation, and provider reputation systems are separate from blocklists entirely.
- We were delisted and listed again a week later
- The listing was a symptom. Until the cause is found — a compromised account, a script, a residential address sending directly — removal is temporary.
- Our address is on a residential range
- Several lists include dynamic and residential ranges on principle, whatever you do with them. The fix is to send through a relay rather than to request removal.
Frequently asked questions
Why do blacklist checkers disagree with each other?
Mostly because of how they handle refused queries. The major lists do not answer lookups from public resolvers, and a checker running from a browser or a shared server gets a refusal rather than an answer. Some report that as listed, some as clean, and few say what actually happened — which is why two checkers can give opposite verdicts for the same address in the same minute.
How do I get removed from a blocklist?
Each list publishes its own removal process, and most are self-service. The part that matters is fixing the cause first: a compromised mailbox, a script sending on your behalf, or a server relaying for anyone. A delisting without that is undone by the next batch, and repeated delistings make the next one harder.
Does being on a blocklist mean my mail will bounce?
It depends entirely which list. A Spamhaus listing affects delivery almost everywhere; a listing on an aggregate list that few receivers consult may change nothing at all. And the reverse is also true — most mail that lands in spam is placed there by provider reputation systems that no blocklist check can see.
Put this on your own site
Free to embed, no attribution required beyond the source link the frame carries itself. It runs entirely in your visitor's browser, sets no cookies and loads no third-party script.
<iframe src="https://runthetests.com/embed/blacklist-check/" width="100%" height="560" style="border:1px solid #e5e5e5;border-radius:8px" title="DNS Blacklist (RBL) Checker" loading="lazy"></iframe>
Preview it at https://runthetests.com/embed/blacklist-check/. Embedded pages are marked noindex, so yours stays the canonical copy — not this one.