Domain & IP Blacklist Checker

Email blacklists (also called blocklists or DNSBLs) are lists of domains and IPs suspected of sending spam or hosting malicious content. Receiving servers check incoming mail against them, and mail from a listed domain or IP is often diverted to spam or rejected outright.

This tool checks your domain or IP against public blacklists that answer over DNS. Note that some major lists (notably Spamhaus) block queries from cloud and browser-based tools, so coverage here is partial by design - treat a clean result as a good sign, not a guarantee.

The common causes: sending unsolicited bulk email that draws spam complaints, a compromised mailbox blasting spam or phishing, ignoring unsubscribe requests or mailing purchased lists, hosting malware, or a misconfigured server that gets exploited as an open relay.

A history of any of these builds a poor reputation that leads to listing. Good authentication (SPF, DKIM, DMARC), clean list hygiene, and conservative sending volumes are the best prevention.

Not listed is good, though it isn't a guarantee of inbox placement on its own. A listing on one or two smaller lists is not a crisis - some minor blacklists are overly aggressive and expire quickly.

A listing on a major list (Spamhaus SBL, Barracuda) or on several at once is a real problem that needs immediate attention. The common causes are a bounce rate above 2 to 3 percent, spam complaints over 0.1 percent, a compromised server, shared-IP contamination, sudden volume spikes, or hitting a spam trap.

Prevention is far cheaper than delisting. Never send to purchased, rented or scraped lists. Configure SPF, DKIM and DMARC on every sending domain. Warm up new IPs and domains gradually over two to four weeks rather than blasting from day one.

Then monitor weekly at a minimum - daily if you run active cold email. Catching a listing early, before it spreads across receivers, is the difference between a quick fix and a rebuild.