Blacklist Checker

Checks whether an IP address or domain appears on the major email blacklists (DNSBLs) — the reputation lists that mailbox providers consult before accepting your mail.

Try it: sendlucid.com/blacklist-checker

What you give it

An IP address or a domain.

What it checks

Your address against two dozen major DNS blacklists — including Spamhaus (SBL/XBL/PBL/DBL), Barracuda, SpamCop, SORBS, UCEPROTECT, and PSBL. It returns how many lists you’re clean on, which (if any) you’re listed on, and the total checked.

Why it matters

A listing on a widely used blacklist — especially Spamhaus — can send your mail straight to spam or get it rejected outright, regardless of how good your authentication is. Blacklists feed the reputation portion of your deliverability score.

How to read it

Clean on everything is what you want. If you’re listed, go to that blacklist’s site to see the reason and request delisting — and fix the underlying cause (compromised account, spam complaints, bad list hygiene) first, or you’ll be relisted.