Instantly verify whether your website domain or mail server IP is blacklisted on major anti-spam databases including Spamhaus ZEN, Barracuda, SpamCop, and SORBS.
When a mailbox provider receives an email from your server, it consults these critical reputation databases before routing messages to the inbox.
The primary blacklist used by corporate and public email providers worldwide. Listing on Spamhaus causes immediate email delivery failures.
Powered by Barracuda enterprise spam firewalls and cloud gateways. Flags IPs sending unsolicited commercial email or harboring malware.
Dynamic list updated automatically based on user spam reports and honeypot traps. Listings expire after 24 hours once spam ceases.
Indexes open mail relays, hijacked proxy servers, and dynamic IP pools known to transmit spam and phishing campaigns.
Everything you need to know about email deliverability, RBL lookups, and rapid delisting procedures.
A DNSBL (DNS-based Blackhole List) or RBL (Real-time Blackhole List) is a real-time reputation database that catalogs IP addresses and domains suspected of sending unsolicited bulk email (spam), distributing malware, or operating compromised mail relays.
When an email arrives at a receiving mail server (such as Gmail, Microsoft 365, or Yahoo Mail), the receiver executes a high-speed reverse DNS query against trusted RBLs (e.g. zen.spamhaus.org). If the query resolves to a loopback address like 127.0.0.2, the message is immediately rejected at the network perimeter or routed directly into the spam folder.
