DNSBL Blacklist Check
Check whether your server IP is on major anti-spam / anti-abuse blacklists — the first thing to check when mail bounces or sites block you.
Check whether an IP is listed on Spamhaus, SpamCop, SORBS and other major anti-spam / anti-abuse blacklists.
What DNSBLs are
DNS blocklists are realtime databases of IPs associated with spam, abuse or compromise. Mail servers consult them on every incoming connection: a Spamhaus listing can reject your mail before it even reaches the spam filter.
Why we query authoritative servers directly
Public resolvers like 8.8.8.8 are policy-blocked by major DNSBLs (Spamhaus answers 127.255.255.x errors through open resolvers). This tool queries each zone’s authoritative nameservers directly, giving you the true listing status.
Getting delisted
First fix the root cause — compromised account, open relay, infected host. Then use each list’s own removal process. Spamhaus delists automatically after the offense stops; repeated relisting points to an unresolved problem.
Need the in-depth Chinese version? Read the full guide.
Related articles
Is Your IP Blacklisted? How DNSBL Works and How to Check Yourself
When mail bounces and CAPTCHAs appear, check your IP reputation first — how DNSBL lookups work, how the major blocklists differ, and the standard delisting process once you're listed.
Why Your Proxy Gets Detected: A Look at IP Disguise
Why sites still recognize you behind a proxy: the full toolkit of detection methods — datacenter IPs, ASN flags, blacklists, consistency signals — and how to test your own disguise score.
Cross-Border Ecommerce Anti-Linking: An IP Checklist for Multi-Account Setups
What multi-account operators fear most is platform link detection — a sequential IP and environment checklist covering geolocation, IP type, blacklists, DNS, WebRTC, and fingerprint consistency, with pass criteria and fixes for each item.
"Residential IP vs Datacenter IP: Why Risk Engines Treat Them Differently"
Both are just IPs, so why does residential broadband carry far better reputation than a datacenter? ASN registration, usage patterns, and risk-engine strategy — plus how to check your own IP.
More in the blog index
Frequently asked questions
My IP is listed but I send no spam — why?
Shared infrastructure: on cloud or home CGNAT ranges a neighbor’s behavior lists the whole range. Check whether the listing is range-based (SBL/CSS) or host-based, and request delisting with evidence of your clean usage.
Which list matters most?
Spamhaus SBL/CSS is the most influential for mail deliverability. Barracuda and SpamCop matter for specific receivers. UCEPROTECT L3 (range listings) is widely considered aggressive and ignored by many operators.
How often should I check?
After any mail deliverability incident, after setting up a new server, and periodically for mail servers — weekly is a sensible cadence.