Blacklist Checker
Check whether your domain or its sending IPs are listed on major blocklists — Spamhaus, Barracuda, SpamCop, SORBS, SURBL.
About the email blocklist checker
Blocklists (formerly blacklists) are DNS-published lists of IP addresses, domains, or URL hosts that have been observed sending spam, malware, or phishing. Inbox providers like Gmail, Microsoft 365, and corporate spam gateways use them as one input among many when scoring mail. A listing on a major blocklist (Spamhaus ZEN, Barracuda, SORBS, SpamCop) typically means a meaningful share of your mail will be deferred, marked as spam, or rejected outright.
This checker queries your IP or domain against the blocklists that actually move the needle for inbox placement, ignoring the dozens of micro-lists that no major provider consults. For each listing it returns the source-of-truth URL where you can see why you were listed and request delisting.
Run it before you start sending from a new IP, when a deliverability dashboard suddenly shows a drop, or when a recipient says your mail is going to spam. A clean check rules out blocklisting as the cause; a hit gives you the specific list and the delisting URL.
How it works
- Reverses the IP into the form expected by DNSBL queries (e.g. `1.2.3.4` → `4.3.2.1`).
- Queries each blocklist's DNS zone (e.g. `4.3.2.1.zen.spamhaus.org`) and inspects the return code.
- Resolves the matching TXT record on a hit to surface the listing reason where the blocklist publishes one.
- Skips deprecated and unmaintained lists — only the lists actively used by major receivers are queried.
- Returns a per-list status with delisting URL where applicable.
Frequently asked questions
What is an email blocklist?
An email blocklist (or DNSBL — DNS-based blocklist) is a public list of IP addresses or domains observed sending spam, malware, or phishing. Inbox providers query these lists during message processing as one signal of trustworthiness. Listings are not permanent; most lists provide a delisting process once the underlying issue is fixed.
Which blocklists actually matter?
Spamhaus ZEN (combines SBL, CSS, XBL, PBL) is the single most consequential — Gmail, Microsoft, and most corporate gateways check it. Barracuda Reputation Block List (BRBL) carries weight with Barracuda-protected enterprises. SpamCop and SORBS are still consulted by some receivers. Most other lists you'll see in legacy 'blacklist checker' tools are unused or unmaintained.
How do I get off a blocklist?
Each blocklist has its own delisting page — check the URL the tool returns. Generally: stop the behavior that got you listed (compromised account, bad list, open relay, malware), wait the list's cool-off period, then submit the delisting form. Spamhaus typically delists within hours once the cause is resolved; SORBS can take days.
Why am I on Spamhaus PBL but not sending spam?
Spamhaus PBL (Policy Block List) is not a spam list — it's a list of IP ranges that ISPs have declared shouldn't send mail directly (residential and dynamic-IP ranges). Listing on PBL is normal for any non-business connection; it means you should send through your ISP's outbound relay, not directly to the internet.
Should I check my domain or my IP?
Both, but for different reasons. IP listings affect mail you send directly from that IP — relevant if you operate your own MTA. Domain (URI) listings affect mail that contains links to or from that domain — relevant if you send through any sender, because if your domain is on URIBL or SURBL the mail body itself triggers spam scoring regardless of the sending IP.