Why check if your domain is blacklisted?
Domain reputation is independent of your IP and of your SPF, DKIM and DMARC setup. URI and RHS blocklists (URIBL, SURBL, Spamhaus DBL) flag the domains found inside message content, so a domain listing filters your mail even when the sending IP is perfectly clean and every record validates.
Impact of a blacklisted domain:
- Emails landing in spam when they carry links to your site
- Brand reputation damage through association with spam
- Phishing exposure when third parties spoof your domain in their campaigns
Three reasons to check regularly:
- Detect if spammers are embedding your domain in spam or phishing
- Identify a compromised website being used as a spam vector
- Verify a new domain before using it for email marketing
Domain blocklists vs IP blacklists
This tool checks the domain, not the IP. It queries URI and RHS blocklists (RHSBL and URIBL style), which flag domains found in the body of messages. A clean result here does not mean your sending IP is clean. To check the mail server IP, use the IP Blacklist Checker.
| Type | Target | Detection | Examples |
|---|---|---|---|
| DNSBL (IP) | Server IP address | IP sending spam | Spamhaus ZEN, Barracuda, SpamCop |
| URIBL / SURBL (Domain) | Domain in content | Domain found in spam | Spamhaus DBL, URIBL Black, SURBL Multi |
Informational, non-blocking lists (such as PBL or UCEProtect L2 and L3) exist on the IP side; the domain lists checked here are all delivery-affecting, so a listing always matters.
How the domain blacklist check works
When a mail server receives an email, it extracts the domains from links and addresses in the body, then checks each one against blocklists with a DNS query. The domain is prepended to the list's zone:
# To check captaindns.com on Spamhaus DBL:
dig A captaindns.com.dbl.spamhaus.org
# Listed (DBL): 127.0.1.x (x decodes the category, see below)
# Listed (URIBL / SURBL): 127.0.0.2
# Clean: NXDOMAIN (no record = not listed)
This tool runs that lookup across all 8 lists in parallel, decodes the return codes (including the Spamhaus DBL category), and turns them into a single clear verdict instead of a raw pile of zone answers.
The verdict and reputation score
The result leads with a 3-tier verdict, and the score supports it:
- Clean : no weight-bearing active-spam list hit.
- At risk : only low-confidence signals, rare for domains and reserved for passive lists.
- Listed : found on at least one authoritative list (Spamhaus DBL, URIBL Black, SURBL Multi), deliverability is impacted now.
The verdict is backed by a 0 to 100 reputation score and a grade, weighted by each list's authority rather than a flat "listed on N of M" count:
| Verdict | Score | Grade | Action |
|---|---|---|---|
| Clean | 95-100 | A+ | No action required |
| Clean | 85-94 | A | Minor signal only, monitor |
| At risk | 70-84 | B | Low-weight signal, review practices |
| Listed | 50-69 | C | Authoritative listing, urgent action |
| Listed | 30-49 | D | Multiple listings, priority delisting |
| Listed | 0-29 | F | Severely compromised, security audit |
Spamhaus DBL listing categories
When your domain hits the Spamhaus DBL, the return code decodes into a category. This is what tells you what to fix, and it is the key difference between a generic lookup and a real diagnosis:
| DBL category | What it means | Remediation focus |
|---|---|---|
| Spam | Domain used in spam campaigns | Stop the spam source, request delisting |
| Phishing | Domain serves phishing pages | Remove phishing content, security audit |
| Malware | Domain serves malware | Clean the host, security audit |
| Botnet C&C | Domain is a botnet command channel | Take down the channel, full compromise response |
| Abused-legit | A legitimate domain that has been compromised | Fix the compromise, not your sending reputation |
Abused-legit is the category that most often surprises a legitimate sender: your own domain was hijacked, hosts an abused redirector, or serves injected malicious content. The fix is incident response on the compromised asset (rotate passwords, patch plugins, close open redirects, remove injected pages). After remediation, the DBL listing auto-expires on its own. Requesting delisting without fixing the root cause causes immediate relisting.
Why a domain gets listed
The most frequent causes of a domain listing:
- Compromised CMS serving injected or defaced pages
- Spammers embedding your links in their campaigns to ride your reputation
- Abused redirect endpoints that forward to malicious destinations
- Brand spoofing where your domain appears in phishing emails
- A brand-new domain flagged by SEM Fresh before it builds a track record
- An old subdomain still serving bad content you forgot about
How to delist a domain
Always fix the root cause before requesting removal, or the domain is relisted. Clean up first: remove injected pages, patch the CMS, close open redirects, stop the offending mail flow.
Spamhaus DBL
Free and self-service. The listing auto-expires once the abuse stops, but only after you fix the underlying cause (it relists otherwise). Use the Spamhaus DBL removal form; expect clearance roughly 24 to 48 hours after remediation.
URIBL
Requires fixing the issue first, then a removal request via URIBL. It may ask for proof of domain ownership, and delays of several days are common.
SURBL
Fix the cause, then SURBL removal generally clears passively as the data ages out. Confirm the remediation proactively rather than waiting passively for the entry to drop.
FAQ - Frequently asked questions
Q: How do I check if my domain is blacklisted?
A: Enter your domain in the tool above and click 'Check'. In seconds you get a verdict (clean, at risk or listed), a reputation score (0-100) and a grade (A+ to F) computed against a curated set of 8 authoritative lists (Spamhaus DBL, URIBL, SURBL).
Q: What is the difference between an IP blacklist and a domain blacklist?
A: A DNSBL (IP) lists the addresses of spamming servers. A URIBL or SURBL (domain) lists domains found in spam content. A clean result here does not mean your sending IP is clean, so test both with the IP Blacklist Checker.
Q: What are URIBL and SURBL?
A: They are RHS and URI blocklists of domains extracted from spam content. Unlike IP blacklists, they analyze the domains in links and addresses inside the message body. SpamAssassin and most filters use them.
Q: What does it mean when my domain is listed?
A: At least one authoritative URI or RHS list (Spamhaus DBL, URIBL Black, SURBL Multi) flagged a domain found in spam content. Emails carrying that domain's links get filtered. Fix the cause, then request delisting.
Q: What do the Spamhaus DBL categories mean?
A: The return code decodes into a category: spam, phishing, malware, botnet C&C or abused-legit. Each one implies a different remediation, from stopping a spam source to a full compromise response.
Q: My domain is abused-legit on DBL, what now?
A: Your legitimate domain is compromised or serving an abused redirector or injected content. Do incident response on the asset (passwords, plugins, open redirects, injected pages), then the DBL listing auto-expires. Do not just request delisting.
Q: Why is my domain on a blacklist?
A: Common causes: a compromised CMS, spammers embedding your links, an abused redirect endpoint, brand spoofing in phishing, a new domain flagged by SEM Fresh, or an old subdomain serving bad content.
Q: How do I remove my domain from a blacklist?
A: Fix the root cause first or you will be relisted. Spamhaus DBL auto-expires 24 to 48 hours after the abuse stops; URIBL needs the issue fixed and may require ownership proof; SURBL clears as the data ages out.
Q: How often should I check my domain's reputation?
A: After any security incident or major email campaign, and immediately if your emails start landing in spam. For routine monitoring, a monthly check is good hygiene for email marketing domains.
Complementary tools
| Tool | Purpose |
|---|---|
| IP Blacklist Checker | Checking your sending IP instead? Test it against the DNSBLs |
| Domain Email Audit | Verify your domain's SPF, DKIM, DMARC and BIMI records |
| Mail Tester | Full end-to-end deliverability test with a score |
| Header Analyzer | Diagnose a rejected or spam-flagged email |
| SPF Inspector | Validate your SPF record and sender authorization |
| Phishing URL Checker | Check if a URL is flagged as phishing or malicious |
| RDAP Lookup | Investigate a suspicious domain via its registration data |
Useful resources
- Spamhaus DBL - Domain Block List (official documentation)
- URIBL - URI Blacklist (verification and delisting)
- SURBL - Spam URI Realtime Blacklists (documentation and statistics)
- Google - Email Sender Guidelines (Gmail requirements)