Blacklist Checker

What Is a Blacklist Checker?

A blacklist checker verifies whether a domain or IP address has been flagged by anti-spam and reputation services. Blacklists are the internet's way of maintaining accountability — when a domain or IP is caught sending spam, hosting malicious content, or participating in phishing, it gets added to one or more public lists.

Once blacklisted, the consequences are immediate: emails from your domain start landing in spam folders, search rankings drop, and visitors may see browser warnings. Getting delisted requires fixing the underlying problem and submitting removal requests to each blacklist provider.

This tool checks a domain or IP against 11 major blacklists plus a set of trust signals (SPF, DMARC, MX, SSL) that indicate healthy configuration.

Blacklists We Check

Domain Blacklists (5 services)

• Spamhaus DBL — the most authoritative domain block list, used by most email providers
• SURBL — tracks URIs found in spam and phishing emails
• URIBL — a collaborative URI reputation database
• NordSpam DBL — regional anti-spam block list
• AHBL RHSBL — Abusive Hosts Blocking List

IP Blacklists (6 services)

• Spamhaus ZEN — combines SBL, XBL, and PBL into a single lookup
• Barracuda — the Barracuda Reputation Block List, widely used by enterprise spam filters
• SpamCop — community-maintained spam reporting blocklist
• SORBS — Spam and Open Relay Blocking System
• CBL — Composite Blocking List focused on infected machines
• PSBL — Passive Spam Block List

Trust Signals We Check

SPF Record

SPF (Sender Policy Framework) tells receiving mail servers which servers are allowed to send email on your behalf. Without SPF, anyone can forge emails "from" your domain. We check for the presence and enforcement level of your SPF record.

DMARC Record

DMARC builds on SPF and DKIM to give you control over what happens when an email fails authentication. As of 2024, Gmail and Yahoo require DMARC for anyone sending more than 5,000 emails per day — making it practically mandatory for legitimate senders.

MX Records

MX records tell the internet where to deliver email for your domain. Their absence signals that your domain can't receive email — often an indicator of abandoned or malicious infrastructure.

SSL Certificate

A valid, non-expired SSL certificate is a basic signal of a maintained site. Sites without HTTPS are more frequently flagged as untrustworthy by browsers and users.

Why Domains Get Blacklisted

• Compromised site sending spam — the #1 cause for legitimate sites
• Contact form abuse — attackers using your form to send spam via your mail server
• Malware hosting — your site was infected with malware and added to malicious-content lists
• Shared hosting IP — a neighbour on your hosting IP was blacklisted and dragged everyone down
• Phishing content — your site was cloned or hacked to host a phishing page
• Legitimate but flagged — some legitimate businesses (mailing list services, e-commerce) get flagged by overly aggressive lists

How to Get Off a Blacklist

1. Identify the cause. If your domain is on Spamhaus DBL, look at what specifically was flagged. Often it's a subpage or API that's been compromised.
2. Fix the underlying issue. Removing the malware, stopping the spam, or cleaning up the mailing practices — delisting requests are rejected if the problem persists.
3. Request delisting. Each blacklist has its own process:
   • Spamhaus: spamhaus.org/lookup
   • SURBL: surbl.org/surbl-analysis
   • URIBL: uribl.com/removal.shtml
   • Barracuda: barracudacentral.org/rbl/removal-request
4. Wait. Automatic delisting usually takes a few hours. Manual review can take 1–3 days.
5. Monitor. Re-compromise is common. Add regular checks to your routine.

Why Blacklist Status Matters

Blacklisting has cascading effects:

• Email deliverability — most providers check Spamhaus and Barracuda before accepting mail
• SEO impact — Google uses spam signals for search ranking
• Browser warnings — Chrome, Firefox, Safari display "Deceptive site" warnings for known malware hosts
• Ad network bans — AdSense and other networks won't approve blacklisted domains
• Payment processor issues — Stripe, PayPal, and similar services screen for blacklist status

For any site handling user data, conducting transactions, or sending transactional email, blacklist monitoring should be part of regular operations.