Blacklist Checker
Check whether an IP or mail server is listed on Spamhaus, SpamCop, Barracuda, SORBS and ten more DNS blacklists.
Check an IP against the mail blacklists
Fourteen DNSBLs queried live. Enter the address your mail is sent from, or a domain to check its first A record.
What the Blacklist Checker does
Blacklist Checker asks fourteen DNS-based blocklists whether an IP address is on them: Spamhaus ZEN, SpamCop, Barracuda, both SORBS zones, CBL, UCEPROTECT level 1, PSBL, WPBL, NiX Spam, Mailspike, DroneBL, s5h.net and GBUdb Truncate. These are the lists that most receiving mail servers and filters actually consult, so a hit here is a direct explanation for bounced or junked mail.
Each list is queried the way a mail server does it: the address is reversed, appended to the list's zone and looked up as an A record. No answer means not listed; a 127.0.0.x answer means listed, and the code tells you which part of the list. Spamhaus returns 127.255.255.x when it refuses a query (public resolvers and heavy users are blocked), which the tool reports as unknown instead of pretending the address is clean.
You can enter a domain instead of an address; the tool resolves its first IPv4 record and checks that. For mail problems, check the address your mail actually leaves from, which is often your provider's server rather than your website.
Step by step
- 01Enter the IPv4 address of the sending server, or a domain to check its first A record.
- 02Press Check. Every list is queried live, which takes a few seconds in total.
- 03Read the summary: how many lists were checked, how many list the address and how many could not answer.
- 04For each listing, follow the link to the list's own lookup page; it explains the reason and has the delisting form.
Common questions
Fix the cause first: a compromised account or script sending spam, an open relay, a missing reverse DNS, or a dynamic address that should not send mail directly. Then use the list's own removal page. Most lists delist within hours once the spam stops; UCEPROTECT and a few others expire listings automatically and charge for faster removal, which you should not pay.
Spamhaus blocks queries that arrive through large public resolvers such as Google or Cloudflare DNS, and it limits free query volume. In those cases it returns a 127.255.255.x code meaning "refused" rather than a real answer. Check the address on check.spamhaus.org directly to be sure.
Only some lists publish IPv6 zones and their query format differs. Most spam filtering still keys on IPv4, and almost every mail provider sends from IPv4 addresses, so the IPv4 check covers the practical cases.
Not for a website or a laptop. Policy lists mark ranges that should not run their own mail server, such as home broadband and some cloud ranges. It only matters if that address tries to deliver mail directly. Send through your provider's SMTP relay instead and the listing is irrelevant.
Keep checking
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Want these fixes done for you?
Our team runs the audit, makes the changes and reports the result.