The Ultimate Guide to DNSBLs: How Email Blacklists Work and How to Get Delisted

What is a DNSBL / RBL?

A DNS-based Blackhole List (DNSBL) or Real-time Blackhole List (RBL) is a dynamic database of IP addresses and domains flagged for sending spam, malware, or suspicious network traffic. Major inbox providers query DNSBLs in real-time to block incoming mail.

Primary Causes of IP Blacklisting

1. Compromised User Credentials:

2. Open Mail Relays:

3. Shared Hosting Reputation:

4. Spam Traps:

Step-by-Step Delisting Process

1. Identify the Specific Blacklist:

2. Stop the Root Cause:

3. Submit a Self-Service Delisting Request: