IP Blacklist Checker - DNSBL & Reputation Report

What is a DNS blocklist (DNSBL/RBL)?

A DNS blocklist - also called a DNSBL or RBL (Real-time Blackhole List) - is a published list of IP addresses (and sometimes domains) with a history of sending spam, hosting malware, or other abuse. Mail servers and security systems query these lists in real time over DNS before accepting a connection. If your sending IP is listed, your email is often rejected or sent to spam, which is why checking and clearing listings is essential for email deliverability.

Why would an IP get blacklisted?

• A compromised account or website sending spam without the owner’s knowledge.
• An open relay or open proxy that lets anyone send mail through your server.
• Malware or a bot on a device behind the IP.
• Hitting a spam trap - sending to an address harvested or used only to catch spammers.
• A “bad neighbour” - on shared hosting or a cloud range, another customer’s abuse can get the shared IP listed.
• Policy listings (e.g. Spamhaus PBL) that simply mark IPs that should not send mail directly, such as residential/dynamic ranges.

What do the three result states mean?

• Listed - the IP returned a listing on that blocklist; we decode the specific return code to show why (e.g. botnet/exploit vs. policy vs. spam source).
• Clean - the list answered and the IP is not on it. We verify each list is actually responding (with a positive control) before trusting a “clean” result.
• Not checked - the list did not answer, timed out, or refuses queries from large public resolvers (Spamhaus and a few others do this). These are excluded from the grade so an unreachable list never fakes a verdict in either direction.

How do I get an IP removed from a blacklist?

Fix the root cause first - secure the compromised account, close the open relay, remove malware, or move off a shared IP - then use each list’s official removal page (linked in the table above). Some lists (SpamCop, PSBL, UCEPROTECT Level 1) expire automatically once abuse stops; others (Spamhaus, Barracuda) require a manual removal request after you have fixed the cause. Requesting delisting without fixing the cause usually leads to a faster re-listing.

I’m on a shared or cloud IP - what now?

If the IP belongs to shared hosting or a VPS/cloud range, you may be listed because of another customer. Ask your provider to address the abuse, or request a dedicated IP and warm it up. Always pair a clean IP with valid reverse DNS (PTR) and SPF, DKIM, and DMARC for the best deliverability.

Related tools

• IP Reputation Aggregator - threat-intel reputation beyond DNSBLs.
• Email Health Check - SPF/DKIM/DMARC + blacklist in one report.
• Domain Health Report - full DNS + email + SSL + reputation scorecard.
• Reverse DNS Lookup - check an IP’s PTR record.
• IP Lookup - geolocation, ISP, and ASN for any IP.