Free Blacklist Checker
Enter any domain to see whether its mail IPs are listed on the major DNS blocklists (Spamhaus, SpamCop, Barracuda, UCEPROTECT and more) — instant, free, no signup. Then let Merlonix watch your domains so a listing never catches you after your mail has already started bouncing.
What is a DNS blocklist (DNSBL / RBL)?
A DNS blocklist (DNSBL, also called an RBL) is a published list of IP addresses that a provider has flagged as a source of spam or abuse. Mail servers query these lists in real time when they receive a message: if the sending IP is listed, the message is commonly rejected outright or filed to spam. Lists like Spamhaus, SpamCop, Barracuda and UCEPROTECT are widely consulted, so a single listing can cause a large share of your mail to bounce or disappear into junk folders. This tool resolves your domain to its IPs and queries each against a curated set of free blocklists.
My domain shows as listed — what do I do?
First find the root cause: a compromised host or web form on your network sending spam, an open mail relay, a marketing send that generated complaints, or a spam-trap hit. Fix that before requesting removal, or you'll just get relisted. Then use each list's delisting page (this tool links directly to the one for every list you're on) to request removal — most process automatically within hours to days once the source of abuse has stopped. If you're on a shared IP (a shared host or ESP), the listing may be a neighbor's fault; escalate to your provider.
Why does the result sometimes say inconclusive?
Several of the largest blocklists — notably Spamhaus and Barracuda — refuse queries that arrive through a large shared or public DNS resolver, and they signal that refusal in a way that could be mistaken for a real listing. Rather than show you a false positive, this tool classifies those refusals as inconclusive. A browser-based one-off check runs through a shared resolver, so it can't always get a definitive answer from every list. Continuous monitoring queries from a stable source and tracks the authoritative result over time.
Does being blacklisted affect more than email?
Primarily it hurts email deliverability — listed IPs get their mail rejected or spam-filed, which quietly kills transactional email (password resets, receipts, alerts) and marketing reach. Some blocklists are also consulted by security tools and web application firewalls, so a listing can occasionally affect reputation scoring more broadly. Either way, sender reputation is slow to build and fast to lose, which is why catching a listing early — before a large volume of mail has already bounced — matters.
How do I keep from getting blacklisted without noticing?
A blocklist listing happens without warning and you usually find out only after mail starts bouncing or a customer says they never got your email. A one-time check is a snapshot of right now. Claim the free Merlonix plan ($0, no credit card) to monitor a few domains continuously, or start a trial to watch your whole portfolio. Merlonix re-checks your domains against the major blocklists on a schedule and alerts you the moment a new listing appears, so you can fix the cause and request delisting before your deliverability collapses.