Free Blacklist Checker

What are Email Blacklists (DNSBLs)?

DNS-based Blackhole Lists (DNSBLs) are real-time databases of IP addresses and domains that have been reported for sending spam or malicious email. Mailbox providers like Gmail, Outlook, and Yahoo check these lists when deciding whether to accept, filter, or reject incoming mail. Being listed on a blacklist can severely impact your email deliverability.

There are two types of blacklists: IP-based lists check if your mail server's IP address has been flagged, while domain-based lists check if your sending domain itself has been reported. Major lists like Spamhaus and Barracuda are widely used by mail providers and have a significant impact on deliverability.

How DNSBL Lookups Work

DNSBL lookups use DNS queries. For IP-based checks, the IP address is reversed and appended to the blacklist domain. For example, to check 1.2.3.4 against Spamhaus, a DNS query is made for 4.3.2.1.zen.spamhaus.org. If an A record is returned (typically 127.0.0.x), the IP is listed. If the query returns NXDOMAIN, the IP is clean.

Common Return Codes

How to Get Delisted

• Spamhaus: Visit the Spamhaus lookup page to check your listing and request removal. SBL listings require a manual request; PBL listings require contacting your ISP.
• Barracuda: Use the Barracuda Central removal request form. Removal is typically processed within 12 hours.
• SpamCop: Listings expire automatically 24–48 hours after the last reported spam from your IP. There is no manual removal process.
• General best practice: Before requesting delisting, identify and fix the root cause — compromised accounts, open relays, or poor list hygiene. Ensure SPF, DKIM, and DMARC are properly configured.