Email Blacklist Check: How to Know If You're Blacklisted (and How to Fix It)
If your domain or sending IP is on a blacklist, your emails are being filtered or rejected. Here's how to check, which lists matter, and how to get delisted.
Open rates are dropping. Emails that used to get replies are met with silence. A client mentions they never got your proposal. Your ESP says everything was "delivered" — but something clearly isn't right.
Time to run an email blacklist check.
Email blacklists (also called blocklists or DNSBLs) are databases of IP addresses and domains identified as sources of spam. If your domain or sending IP is listed, a significant chunk of your emails will be filtered into spam or rejected outright — often without any notification.
Getting blacklisted isn't permanent, but it requires fast action. Here's how to find out if you're listed, which blacklists matter, and exactly how to fix it.
How Email Blacklists Work
When you send an email, the receiving server queries blacklist databases to check whether your sending IP or domain appears on any known blocklists. If you're listed, your email either gets routed to spam, rejected with a bounce, or silently deprioritized.
There are hundreds of blacklists. Not all carry the same weight. Getting listed on Spamhaus is a five-alarm fire. Getting listed on an obscure regional blacklist might have minimal impact.
The Blacklists That Actually Matter
Spamhaus (SBL/DBL) — The most influential blacklist globally. A listing here means serious spam-related activity was detected. It will devastate your deliverability across nearly every inbox provider.
Barracuda (BRBL) — Widely used by corporate email gateways. If your recipients include businesses, a Barracuda listing hits hard.
SpamCop — Triggered by spam complaints or trap hits. Auto-expires within 24–48 hours if the behavior stops. One of the more forgiving major lists.
SORBS — Maintains several sub-lists for open relays, dynamic IPs, and confirmed spam. Listings can be persistent.
UCEPROTECT — Three-tiered system (individual IPs → IP ranges → entire ISPs). Can be aggressive.
Gmail, Microsoft, Yahoo — Maintain private internal blocklists you can't directly query. Monitor through Google Postmaster Tools and Microsoft SNDS.
5 Ways to Run an Email Blacklist Check
1. Multi-Blacklist Checker (Fastest)
Use a multi-blacklist checker to scan your domain or IP against 100+ blacklists in 30 seconds.
2. Check Individual Blacklists Directly
Go to Spamhaus or Barracuda's lookup tools for detailed information on why you're listed and what evidence they have.
3. Read Your Bounce Messages
Blacklist-caused bounces often contain specific keywords: "blocked," "blacklist," "blocklist," "rejected due to spam." Some include the blacklist URL for removal requests.
4. Provider-Specific Reputation Tools
Gmail: Google Postmaster Tools — monitor spam rate, reputation grade, authentication. Outlook: Microsoft SNDS — complaint rates, spam trap hits, filtering.
5. Automated Continuous Monitoring
Manual checks work for one-time audits, but listings can appear at any time. MailVitals monitors your domain against 34 blacklists continuously and alerts you instantly when a listing appears.
How to Fix a Blacklist Listing
Step 1: Find the Root Cause
Common triggers: spam trap hits (bad list data), high complaint rates, compromised server, poor list hygiene, or shared IP contamination.
Step 2: Fix the Problem First
Requesting removal without fixing the root cause guarantees relisting. Clean your list. Fix authentication (SPF, DKIM, DMARC). Secure your infrastructure.
Step 3: Request Delisting
Each blacklist has its own process — Spamhaus requires evidence of remediation, Barracuda has self-service removal, SpamCop auto-expires. Fix first, then request.
Step 4: Monitor After Removal
Watch closely for 2–4 weeks. Relisting means the root cause wasn't fully resolved.
How to Prevent Getting Blacklisted
Maintain ruthless list hygiene. Keep spam complaints under 0.1%. Warm up new domains gradually. Authenticate everything. And monitor continuously — MailVitals watches 34 blacklists around the clock so you never get blindsided.
👉 Related: Why Are My Emails Going to Spam? · Why Did My Sender Reputation Drop?