Blacklist Checker

Enter a domain or IP address to check whether your mail servers appear on any of 10 public DNS blocklists.

Live lookup, no account required. Monitor DMARC alignment across all your senders.

Why your sending IP ends up on a blocklist

DNS blocklists (DNSBLs) track IP addresses associated with spam, open relays, compromised hosts, and policy violations. When a receiving server checks your IP and finds a hit, it can reject or filter your mail before DMARC even runs. A listing in Spamhaus ZEN or Barracuda can suppress deliverability across large portions of the internet regardless of how clean your DMARC record is.

What the blocklists checked here cover

Spamhaus ZEN:Combines SBL (known spam sources), XBL (exploited/hijacked IPs), and PBL (policy block list). The highest-signal list for mail filtering.
Barracuda:Tracks IP reputation from Barracuda appliance network. Common in enterprise mail environments.
SpamCop:User-reported spam sources. Listings expire quickly but indicate recent complaints.
SORBS:Covers spam, open relays, and dynamic IP ranges.

Frequently asked questions

Does this check domain blacklists or IP blacklists?

Both. Enter a domain and the tool resolves your MX records to find sending IPs, then checks both the domain and the IPs against each list, the same way a receiving server evaluates your domain's reputation.

Why do I keep getting blacklisted even after removal?

Removal without fixing the root cause, a high complaint rate, a compromised account, or missing SPF/DKIM/DMARC, results in relisting within days. Check your email authentication setup and your DMARC aggregate reports to find where bad mail is originating before requesting removal.

My IP is listed but I don't send spam, what happened?

Shared hosting and cloud IPs cycle through many tenants. A previous tenant may have been a spammer. Request delisting and consider a dedicated IP if you're on shared infrastructure. If the listing is recent, a compromised account or misconfigured relay on your side is more likely.

How does this relate to DMARC?

DMARC aggregate reports show you sending sources and failure rates, but they don't tell you which sources are blacklisted. This tool fills that gap. If your DMARC reports show a source with high failure rates, check that IP here to see whether a blocklist listing is compounding the problem.

Blocklist hits are one signal. DMARC is the policy layer.

If you're seeing delivery failures, check your email authentication setup to rule out SPF, DKIM, or DMARC misconfigurations alongside any blocklist issues.

DMARCdrift monitors your DMARC alignment across all sending sources: which IPs are authenticating correctly, which are failing, and when alignment drops.

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