Check email blacklists with MXToolbox blacklist check (covers 80+ lists), MultiRBL.valli.org (most exhaustive), or Spamhaus's own lookup. Most listings are recoverable in 24-72 hours if you fix the cause. Spamhaus SBL, CSS, and CBL listings are the highest impact; minor RBLs are mostly noise.
How to Check If Your Domain or IP Is on a Blacklist
A blocklist (or blacklist) listing is one of the fastest ways for deliverability to break. The mail starts deferring or rejecting outright, recipients stop receiving you, and the recovery clock starts the moment you fix the cause and submit a delisting request. This guide covers how to check both IP and domain blocklists efficiently, which lists actually matter, and how to interpret results so you don't spend a weekend panicking over a minor RBL no one uses.
For deeper context on what blocklists are and how they work, see the email blacklists guide.
The fast triage tools
| Tool | Coverage | Speed | Cost |
|---|---|---|---|
| MXToolbox blacklist check | 80+ lists | 30 seconds | Free |
| MultiRBL.valli.org | 300+ lists | 1-2 minutes | Free |
| Spamhaus check.spamhaus.org | Spamhaus only | 5 seconds | Free |
| HetrixTools | 100+ lists + monitoring | Real-time | Free + paid |
| DNSChecker blacklist | 50+ lists | 30 seconds | Free |
| Talos Intelligence | Cisco's reputation data | 5 seconds | Free |
| Barracuda Reputation lookup | Barracuda BRBL | 5 seconds | Free |
The fastest first move: paste your IP into MXToolbox. Two minutes, covers 80% of lists you care about.
IP blacklist checks
For sending IPs:
# Quick CLI check using Spamhaus
dig +short 1.2.3.4.zen.spamhaus.org
# Reverse the IP and append the blocklist domain
# If it returns a 127.0.0.x address, you're listed
For most senders, the workflow is:
- Get your current sending IPs from your ESP dashboard or SMTP relay settings
- Run them through MXToolbox to check 80+ lists
- Run them through Spamhaus specifically to get authoritative result
- Note any listings with which list and when listed
- Follow each list's delisting process
Domain blocklist checks
Domains can be on:
- URI blocklists (Spamhaus DBL, SURBL, URIBL) — your domain in email content
- Domain reputation lists (Cisco Talos, Google Safe Browsing) — domain associated with malicious activity
- Tracking domain lists — your click-tracking domain flagged separately
# Check Spamhaus DBL
dig +short yourdomain.com.dbl.spamhaus.org
# Check SURBL
dig +short yourdomain.com.multi.surbl.org
Check both your sending domain (e.g., news.acme.com) and any tracking domains (e.g., click.acme.com or usXX.list-manage.com if you use Mailchimp without a custom tracking domain — see list-manage.com explained).
The Spamhaus lists explained
| List | Type | What it lists | Impact |
|---|---|---|---|
| SBL (Spamhaus Block List) | IP | Manually-listed spammers | High |
| XBL (Exploits Block List) | IP | Compromised hosts, botnets | High |
| CSS (Composite Snowshoe) | IP | Snowshoe spammers | High |
| PBL (Policy Block List) | IP | Dynamic/residential IPs not authorized for direct mail | Medium |
| DBL (Domain Block List) | Domain | Spam/malicious domains | High |
| AuthBL | IP | Authenticated user listings | Medium |
| ZEN | Combined | IP listings (SBL+CSS+XBL+PBL combined) | High |
| ROKSO | IP/operator | Repeat offenders, hard delisting | High |
The lists that hurt most: SBL, CSS, XBL, DBL. PBL is normal for dynamic IPs and doesn't matter if you're sending through a proper relay.
Practitioner note: A PBL listing on your home internet IP is expected — Spamhaus PBL lists virtually all consumer IP ranges as "not authorized for direct mail submission." This doesn't mean anything if you send through Gmail, your ESP, or any relay. PBL only matters if you're trying to send directly from a residential IP (which you shouldn't be anyway).
What actually matters
Mailbox providers query specific lists. The hierarchy:
Tier 1 (mailbox providers actively use these):
- Spamhaus SBL, CSS, XBL, DBL
- Spamhaus ZEN (combined IP list)
- SpamCop
- Barracuda BRBL
- SURBL multi
Tier 2 (used by some receivers):
- SORBS
- UCEPROTECT level 1
- Invaluement
- LashBack
Tier 3 (mostly noise):
- Hundreds of small RBLs operated by individuals
- UCEPROTECT level 2/3 (controversial methodology)
- DroneBL
If MXToolbox shows you on UCEPROTECT level 3 only, it's probably not affecting deliverability. If you're on Spamhaus SBL, every send to a major provider is failing.
After you find a listing
The recovery workflow:
- Identify the cause. Open relay? Compromised account? Cold email gone wrong? Compromised CMS sending phishing? You can't request delisting without understanding why you got listed.
- Fix the cause completely. Don't request delisting if the problem is still happening — you'll just get re-listed and it'll take longer next time.
- Submit delisting request. Each blocklist has its own URL:
- Spamhaus: check.spamhaus.org (each listing has a "request delisting" link)
- SpamCop: spamcop.net (the listing page links to delisting)
- Barracuda: barracudacentral.org/rbl/removal-request
- SORBS: sorbs.net/delisting/
- Wait the stated time. 24-72 hours is typical. Some lists are automatic; some require manual review.
- Monitor recurrence. Set up automated blocklist monitoring (HetrixTools, MXToolbox, or your ESP's built-in).
Setting up ongoing monitoring
Once you're clean, don't wait for the next listing to find out. Free options:
- MXToolbox monitoring — free for one IP, paid for more
- HetrixTools — free for two monitors with daily checks
- Spamhaus reputation portal — free for some lists with notification
- Postmark DMARC — surfaces some authentication issues that correlate with listings
Practitioner note: Half the agencies I work with don't monitor blocklists at all and find out about listings days later when client complaints mount. Set up daily HetrixTools checks on every sending IP and every From-domain. It's free and it catches problems before clients do.
If you've found yourself on a blocklist and want help with delisting requests, root-cause analysis, or setting up ongoing monitoring, book a consultation. I do blocklist recovery and reputation repair for senders dealing with sudden deliverability drops.
Sources
- MXToolbox Blacklist Check — MXToolbox
- Spamhaus Lookup — Spamhaus
- SURBL — URI blocklist — SURBL
- Barracuda Reputation lookup — Barracuda
- M3AAWG IP Reputation BCP — M3AAWG
v1.0 · May 2026
Frequently Asked Questions
How do I check if my IP is on a blacklist?
Use MXToolbox blacklist check (mxtoolbox.com/blacklists.aspx) — enter your IP and it checks 80+ public blocklists in 30 seconds. For more exhaustive coverage, MultiRBL.valli.org checks 300+. For Spamhaus specifically (the most important), use Spamhaus's own lookup at check.spamhaus.org.
How do I check if my domain is on a blacklist?
MXToolbox checks both IP and domain blacklists. Surbl.org checks URI blocklists (your domain appearing in spammy email bodies). For Spamhaus DBL (domain blocklist) specifically, use dbl.spamhaus.org/lookup. Check both your sending domain and your tracking/click domains.
What's the difference between IP and domain blacklists?
IP blacklists list sending IP addresses that have produced spam. Domain blacklists (URI blocklists) list domains that appear in spam content — your sending domain, tracking domain, or any link domains. Both affect deliverability but through different mechanisms. IPs are easier to recover from than persistent domain issues.
How do I get off a blacklist?
First, fix the cause (cleaning a bad list, stopping a compromised sender, fixing an exposed open relay). Then submit a delisting request to the blocklist operator — most have a web form. Spamhaus, Barracuda, and SORBS process delists within 24-72 hours for legitimate senders. Don't request delisting until you've actually fixed the cause.
Which email blacklists actually matter?
Spamhaus (SBL, CSS, XBL, DBL, PBL) is the most-used blocklist family — major mailbox providers query Spamhaus. SpamCop, Barracuda Reputation, and SORBS also have meaningful impact. Most minor RBLs are either niche or operated by single individuals and have limited use. Don't panic over listings on lists you've never heard of.
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