Email Blacklist (RBL)
A database of IP addresses and domains known to send spam, used by ISPs to filter incoming email.
Email blacklists (also called RBLs — Real-time Blackhole Lists, or DNSBLs) are databases maintained by organizations like Spamhaus, Barracuda, and SpamCop. ISPs query these lists to decide whether to accept, reject, or spam-filter incoming emails.
Major blacklists:
- Spamhaus SBL/XBL/PBL (most widely used)
- Barracuda Reputation Block List
- SpamCop
- SORBS
- UCEProtect
How you get blacklisted:
- High bounce rates from sending to invalid addresses
- Spam complaints from recipients
- Sending to spam traps (recycled or pristine)
- Compromised sending infrastructure
- Sudden large volume increases
How to get delisted: Each blacklist has its own delisting process, usually requiring you to fix the underlying issue and submit a removal request.
SendSure's Blacklist Monitoring feature checks your domains against major blacklists every 6 hours and alerts you immediately if a listing is detected.
Related Terms
Sender Reputation
A score assigned by ISPs to your email sending domain/IP that determines whether your emails reach the inbox.
Bounce Rate
The percentage of emails that could not be delivered to the recipient's inbox.
SPF (Sender Policy Framework)
A DNS record that specifies which mail servers are authorized to send email on behalf of your domain.
Related Blog Posts
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