Email & IP blacklist checker
Is your server on a spam blocklist? Check your domain or IP against the major DNSBLs — Spamhaus, Barracuda, SpamCop, SORBS, PSBL, MailSpike and more — in one shot.
The first check when email stops landing
DNS-based blocklists (DNSBLs) are the invisible gatekeepers of email: receiving servers query them for every incoming connection, and a listing — even on a single list — can mean bounces, junk folders, or silent rejection. Because listings often happen without any notification to you, checking them is a routine part of email troubleshooting.
This tool resolves your domain to its IP (or accepts an IP directly) and queries the major public blocklists from one of our monitoring nodes, translating the technical 127.x return codes into a clear listed / clean / unqueryable verdict per list.
If you run mail servers, SiteFlux can watch them continuously — uptime, ports and response times — so you learn about the network problems that lead to blacklisting before your deliverability does.
Frequently asked questions
How do I know if my IP is blacklisted?
The clearest symptom is mail bouncing with 5xx spam errors, but many blocklists silently hurt deliverability without visible bounces. Checking your sending IP against the major DNSBLs — as this tool does — is the standard first diagnostic step.
Why is Spamhaus shown as 'blocked' for my check?
Spamhaus, like several list operators, refuses queries coming from datacenter/cloud networks to protect its infrastructure. When that happens the tool shows 'Blocked' instead of guessing — you can verify that specific list directly on the operator's website.
How does an IP end up on a blocklist?
Common causes: sending spam (wittingly or via a compromised account), an open mail relay, a hacked site sending phishing, or simply inheriting an IP with a bad history from your provider. Shared hosting IPs can be listed because of other customers' behavior.
How do I get removed from a blocklist?
Fix the root cause first — close the relay, remove the malware, secure the accounts — otherwise you'll be relisted. Most operators (Spamhaus, Barracuda, SpamCop) have a self-service delisting form; PSBL and similar automatic lists expire entries after a few days of clean traffic.
Check your IP once — SiteFlux keeps watching your servers 24/7 so the problems that cause listings never go unnoticed.
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