RBL – Realtime Blackhole List

Short for Realtime Blackhole List, a list of IP addresses whose owners refuse to stop the proliferation of spam. The RBL usually lists server IP addresses from ISPswhose customers are responsible for the spam and from ISPs whose servers are hijacked for spam relay.

As subscribers to the RBL, ISPs and companies will know from which IP addresses to block traffic. Most traffic blocking occurs during the SMTP connection phase. The receiving end will check the RBL for the connecting IP address. If the IP address matches one on the list, then the connection gets dropped before accepting any traffic from the spammer. Some ISPs, though, will choose to blackhole (or ignore) IP packets at their routers. The goal here is to block all IP traffic.

It is important to note that all e-mail and packet blocking is done by the recipient, not the RBL administrator, which is only responsible for bouncing spam that is directed at its servers.

The RBL was created by Mail Abuse Prevention System (MAPS) LLC., but there are other entities that keep RBLs aside from MAPS.

Webopedia Staff
Webopedia Staff
Since 1995, more than 100 tech experts and researchers have kept Webopedia’s definitions, articles, and study guides up to date. For more information on current editorial staff, please visit our About page.

Top Articles

List of Windows Operating System Versions & History [In Order]

The Windows operating system (Windows OS) refers to a family of operating systems developed by Microsoft Corporation. We look at the history of Windows...

How to Create a Website Shortcut on Your Desktop

Website Shortcut on Your Desktop reviewed by Web Webster   This Webopedia guide will show you how to create a website shortcut on your desktop using...

What are the Five Generations of Computers? (1st to 5th)

Reviewed by Web Webster Each generation of computer has brought significant advances in speed and power to computing tasks. Learn about each of the...

Hotmail [Outlook] Email Accounts

Launched in 1996, Hotmail was one of the first public webmail services that could be accessed from any web browser. At its peak in...

Crypt888 Ransomware

Crypt888, also known as Mircop, is ransomware that encrypts files on desktops, downloads,...

AutoLocky Ransomware

AutoLocky is ransomware written in the popular AutoIt scripting language. It uses strong...

Data Governance

Data governance is a term used to refer to the management of processes,...