Check if your IP address or domain is blacklisted on major RBLs including Spamhaus, SpamCop, Barracuda, SORBS, and 70+ more. Try IPs like 8.8.8.8 or domains like google.com to see how the tool works.
Email deliverability problems? Your IP or domain might be blacklisted. This tool queries over 70 blacklists in parallel, giving you instant visibility into your reputation status. Identify listings quickly so you can take action and restore your sending reputation.
RBLs (Realtime Blackhole Lists) use DNS to publish lists of IP addresses and domains associated with spam or malicious activity. When you query an IP, it's reversed (e.g., 1.2.3.4 becomes 4.3.2.1) and appended to the RBL's domain. A DNS response indicates the IP is listed; no response means it's clean.
This tool sends parallel UDP DNS queries to all 70+ blacklists simultaneously, collecting responses in seconds rather than querying each list one at a time. For domains, we check both domain-based blacklists (like Spamhaus DBL) and resolve the domain to its IP to check IP-based lists.
Response Codes: Different return values indicate different listing reasons. For example, Spamhaus returns 127.0.0.2 for SBL (known spam sources), 127.0.0.4 for XBL (exploited systems), and 127.0.0.10-11 for PBL (policy blocks).
A blacklist, also called an RBL (Realtime Blackhole List) or DNSBL (DNS-based Blackhole List), is a database of IP addresses or domains known for sending spam or malicious content. Email servers query these lists to decide whether to accept, reject, or flag incoming messages. Being listed can severely impact email deliverability.
Common reasons include: sending spam (intentionally or via compromised accounts), hosting malware or phishing content, having an open relay or proxy, being part of a botnet, or sharing an IP range with spammers. Sometimes legitimate senders get listed due to misconfigured servers or compromised user accounts.
Each blacklist has its own delisting process. Generally, you need to: 1) Identify and fix the underlying issue (stop spam, patch vulnerabilities), 2) Visit the blacklist's website and follow their removal request process, 3) Wait for the delisting to propagate. Some lists auto-expire after a period of clean behavior.
The most impactful blacklists are Spamhaus (ZEN, SBL, XBL, PBL), SpamCop, Barracuda, and SORBS. These are widely used by major email providers and corporate mail servers. Being listed on these can significantly affect your email deliverability, while smaller regional lists may have less impact.
For email servers and business domains, check weekly or set up automated monitoring. After a spam incident or security breach, check daily until resolved. For general websites, monthly checks are usually sufficient. Proactive monitoring helps catch issues before they impact deliverability.
DNS Explorer — Run bulk DKIM, SPF, and DMARC lookups across thousands of domains. Built for security teams, MSPs, and IT administrators who need to audit email authentication configurations across their entire domain portfolio.
Start free DNS Explorer trial14-day full-feature trial
... Blacklist Check In Progress ...
Checking against blacklist sources. This may take up to 30 seconds.