Your emails are being blocked because one or more components in your email campaign have been flagged by public blacklists (RBLs/DBLs). This could be your sending IP address, your domain, or URLs included in your email content. Email providers use these blacklists as a first line of defense against spam, and being listed can severely impact your email deliverability across multiple platforms.
Quick Diagnosis: Identifying Blacklist Issues
Bounce Message Examples
Email blocked due to listed URLs or IPs/domains on public blacklists (RBLs/DBLs).
Understanding Blacklist Blocks
Key Concepts
Important Information:
Blacklists are third-party databases that track suspicious IPs, domains, and URLs
Major email providers (Gmail, Outlook, Yahoo) consult multiple blacklists before accepting emails
Being blacklisted affects ALL emails from your account, not just specific campaigns
Blacklist removal can take 24-72 hours even after resolving the underlying issue
Some blacklists automatically remove entries after a period of good behavior
Common Blacklist Types
IP-Based Blacklists (RBLs):
Spamhaus SBL/CSS/XBL/PBL - Most widely used
Barracuda Reputation Block List
SURBL - Focuses on spam URLs
SpamCop - Community-driven reporting
Domain/URL Blacklists (DBLs):
Spamhaus DBL - Domain reputation
URIBL - URL reputation tracking
SURBL - Spam URL realtime blocklist
Google Safe Browsing - Malware/phishing protection
Step-by-Step Blacklist Resolution
Step 1: Identify What's Blacklisted
Check Your Sending Infrastructure:
Find your sending IP:
Go to Settings → Email Services → Sending Domain and IP
Note your configured sending domain and any IP information displayed
If using shared infrastructure, contact support for IP details
Use external blacklist checkers:
Visit MXToolbox.com → Blacklist Check
Enter your sending IP address
Check your sending domain separately
Test any URLs frequently used in your campaigns
Step 2: Analyze Email Content
Review Recent Campaigns:
Access your campaign history:
Go to Marketing → Emails → Campaigns
Review campaigns sent in the last 7-14 days
Look for any new URLs, domains, or shortened links