01What is this check for?
DNSBLs (DNS blocklists) track IP addresses that have sent spam or hosted malicious content. Mail servers query them in real time: if your sending IP is listed, your email is rejected or filed as spam before anyone reads it — often with no notification.
This tool queries the main lists simultaneously for an IP address. You can also enter a domain: its A record is resolved and that IP is tested. Cross-check with our SPF/DKIM/DMARC test: a clean IP with shaky authentication still sends your messages to spam.
02Understanding the statuses
- Not listed
- The list does not know this address (NXDOMAIN response). This is the expected, healthy result.
- Flagged
- The address is listed: the list returns a 127.0.0.x code and usually a reason. Your email to servers querying this list is compromised.
- Not queryable
- Spamhaus refuses queries coming from public DNS resolvers — which this site uses. It is neither a good nor a bad sign: follow the link to check with them directly.
- No answer
- The list did not answer in time (outage, quota). Try again later.
- False positives
- A shared IP can be listed because of a neighbour. UCEPROTECT level 1 in particular lists broadly: don't panic over an isolated flag on that list.
03My IP is listed: what now?
First find the cause, otherwise delisting won't stick: an infected machine sending spam, a contact form abused as a relay, a hijacked mailbox, or an SMTP server configured as an open relay. Check your sending logs before requesting anything.
Then request delisting on each list's site (links in the table). Most delist automatically after a few days without new complaints. Also fix your SPF, DKIM and DMARC setup: flawless authentication greatly reduces new flags.
04Frequently asked questions
Why does Spamhaus show “not queryable”?
Spamhaus blocks queries coming from public DNS resolvers (Cloudflare, Google) to control its load: it then answers a 127.255.255.x error code. Since this site queries the lists over DNS over HTTPS, it receives that refusal. Rather than display a false result, we state it clearly and link to Spamhaus's official form, which remains the reference.
Which IP should I test?
The one that actually sends your email, not your website's nor your home connection's. If you use Google Workspace, Microsoft 365 or an email service, their servers do the sending and they manage that reputation. Test your own IP if you host your SMTP server. You can read the sending address in the Received header of the last email you sent yourself.
How long does a listing last?
It depends on the list: some delist automatically after 24 hours to 7 days without new reports, others require a manual request. Delisting without fixing the cause won't last: you will be re-listed on the next suspicious send, often with a longer cooldown.
Does a listed IP mean I have been hacked?
Not necessarily. Common causes without a breach: a shared IP whose other tenant spammed, a recycled IP whose previous holder had a bad reputation, a badly configured bulk send, or a recipient complaint. But a sudden spike of flags across several lists is a serious signal: check your machines and accounts.
Do all lists carry the same weight?
Far from it. Spamhaus is by far the most widely used by major mailbox providers, followed by SpamCop and Barracuda. Conversely, UCEPROTECT levels 2 and 3 list entire provider blocks and are rarely honoured. A flag on a marginal list often has no concrete effect on your deliverability.