Email blacklist checker

An email blacklist, also called a DNSBL or RBL, is a real-time database of IP addresses and domains known for sending spam. Receiving servers query these lists over DNS while your message is still in transit, and use the answer to decide whether to accept it, route it to spam, or reject it outright. A listing is published by the blacklist operator, not by Gmail or Outlook, but the major providers read those lists and act on them.

Enter your domain or sending IP in the checker above and run the scan. The tool resolves your domain to its mail-sending IP addresses, then queries both domain-based lists such as SURBL and IP-based lists such as Spamhaus ZEN, SpamCop and Barracuda Central. You get the status of every list, the reason code where the operator publishes one, and a delisting link for each list that has you flagged.

Fix the cause first, because most lists re-add a domain that is delisted while still sending badly. Find the compromised account, open relay, bad list segment or malware that triggered the listing and stop it. Then submit a removal request on the operator's own site: Spamhaus, SpamCop and Barracuda each run their own form. Some lists expire automatically once the abuse stops and need no request at all.

It depends on the list. Automated lists such as the Spamhaus PBL and CBL usually clear within hours of a successful request. SpamCop entries age out on their own, typically within 24 hours of the last spam report. Manually reviewed listings such as the Spamhaus SBL can take several days, and repeat listings take longer each time. Sending volume should stay low until the listing clears.

The two are listed independently. IP listings usually follow the behaviour of the sending server, which on shared infrastructure includes every other sender on that IP. Domain listings follow the domain in the message body or the From header, and usually come from URLs in your content. You can be listed on either side alone, which is why this tool checks both and reports them separately.

Spamhaus ZEN is the one to care about most, because Gmail, Outlook and most corporate filters consult it directly, and it combines the SBL, XBL, CSS and PBL zones in a single query. SpamCop and Barracuda Central carry real weight too. Beyond those, most of the smaller lists have little effect on inbox placement on their own, though several at once is a signal that something is genuinely wrong with your sending.

Yes, on the major lists. A Spamhaus ZEN listing commonly means outright rejection at the SMTP layer with a bounce that names the list. Smaller lists are more likely to push mail to the spam folder than to block it. Neither provider publishes exactly which lists it weighs, so treat a listing on a tier-one list as an incident and a listing on an obscure one as a warning to investigate.

Weekly is enough for a stable sending setup, and immediately whenever open rates drop, bounces rise, or a bounce message mentions a blacklist by name. If you are warming new domains or running cold outreach, check before each campaign: a listing that appears mid-send does far more damage than one caught early.

DNSBL operators rate-limit queries from shared and cloud resolvers. Instead of a listing, a refused query comes back as an answer in the 127.255.255.0/24 range, or as 127.0.0.1 from SURBL. The checker treats both as unknown, not clean: the list is marked "Couldn't check" with the reason "Blacklist refused the query". If a list answers with an ordinary web address instead of a 127.x code, it is not a real listing either, so the list is marked "Couldn't check" with the reason "Blacklist gave a non-listing answer". Neither error means you are listed. If coverage falls below half the lists, the result is marked unreliable rather than scored.

Yes. On shared sending infrastructure the IP reputation is collective, so another tenant's spam can list the address you send from even when your own sending is clean. You cannot fix that from your side beyond asking the provider to act. It is the main argument for dedicated or per-mailbox IPs on cold outreach, where a single neighbour can take out a whole campaign.

No. Delisting removes the block, but the reputation damage that caused it persists at the mailbox providers, who keep their own internal reputation separate from any public list. Expect placement to recover over days to weeks of clean sending, not instantly. Reduce volume, send to engaged recipients first, and keep authentication passing while reputation rebuilds.

Yes, entirely free with no sign-up and no limit on the number of checks. It queries the DNSBLs live at the moment you run it, so the result reflects the current state of each list rather than a cached lookup.